root/crypto/openssh/ssh-keygen.c
/* $OpenBSD: ssh-keygen.c,v 1.477 2024/12/04 14:24:20 djm Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Identity and host key generation and maintenance.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

#include "includes.h"

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>

#ifdef WITH_OPENSSL
#include <openssl/evp.h>
#include <openssl/pem.h>
#include "openbsd-compat/openssl-compat.h"
#endif

#ifdef HAVE_STDINT_H
# include <stdint.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#ifdef HAVE_PATHS_H
# include <paths.h>
#endif
#include <pwd.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <locale.h>
#include <time.h>

#include "xmalloc.h"
#include "sshkey.h"
#include "authfile.h"
#include "sshbuf.h"
#include "pathnames.h"
#include "log.h"
#include "misc.h"
#include "match.h"
#include "hostfile.h"
#include "dns.h"
#include "ssh.h"
#include "ssh2.h"
#include "ssherr.h"
#include "ssh-pkcs11.h"
#include "atomicio.h"
#include "krl.h"
#include "digest.h"
#include "utf8.h"
#include "authfd.h"
#include "sshsig.h"
#include "ssh-sk.h"
#include "sk-api.h" /* XXX for SSH_SK_USER_PRESENCE_REQD; remove */
#include "cipher.h"

#define DEFAULT_KEY_TYPE_NAME "ed25519"

/*
 * Default number of bits in the RSA, DSA and ECDSA keys.  These value can be
 * overridden on the command line.
 *
 * These values, with the exception of DSA, provide security equivalent to at
 * least 128 bits of security according to NIST Special Publication 800-57:
 * Recommendation for Key Management Part 1 rev 4 section 5.6.1.
 * For DSA it (and FIPS-186-4 section 4.2) specifies that the only size for
 * which a 160bit hash is acceptable is 1kbit, and since ssh-dss specifies only
 * SHA1 we limit the DSA key size 1k bits.
 */
#define DEFAULT_BITS            3072
#define DEFAULT_BITS_DSA        1024
#define DEFAULT_BITS_ECDSA      256

static int quiet = 0;

/* Flag indicating that we just want to see the key fingerprint */
static int print_fingerprint = 0;
static int print_bubblebabble = 0;

/* Hash algorithm to use for fingerprints. */
static int fingerprint_hash = SSH_FP_HASH_DEFAULT;

/* The identity file name, given on the command line or entered by the user. */
static char identity_file[PATH_MAX];
static int have_identity = 0;

/* This is set to the passphrase if given on the command line. */
static char *identity_passphrase = NULL;

/* This is set to the new passphrase if given on the command line. */
static char *identity_new_passphrase = NULL;

/* Key type when certifying */
static u_int cert_key_type = SSH2_CERT_TYPE_USER;

/* "key ID" of signed key */
static char *cert_key_id = NULL;

/* Comma-separated list of principal names for certifying keys */
static char *cert_principals = NULL;

/* Validity period for certificates */
static u_int64_t cert_valid_from = 0;
static u_int64_t cert_valid_to = ~0ULL;

/* Certificate options */
#define CERTOPT_X_FWD                           (1)
#define CERTOPT_AGENT_FWD                       (1<<1)
#define CERTOPT_PORT_FWD                        (1<<2)
#define CERTOPT_PTY                             (1<<3)
#define CERTOPT_USER_RC                         (1<<4)
#define CERTOPT_NO_REQUIRE_USER_PRESENCE        (1<<5)
#define CERTOPT_REQUIRE_VERIFY                  (1<<6)
#define CERTOPT_DEFAULT (CERTOPT_X_FWD|CERTOPT_AGENT_FWD| \
                         CERTOPT_PORT_FWD|CERTOPT_PTY|CERTOPT_USER_RC)
static u_int32_t certflags_flags = CERTOPT_DEFAULT;
static char *certflags_command = NULL;
static char *certflags_src_addr = NULL;

/* Arbitrary extensions specified by user */
struct cert_ext {
        char *key;
        char *val;
        int crit;
};
static struct cert_ext *cert_ext;
static size_t ncert_ext;

/* Conversion to/from various formats */
enum {
        FMT_RFC4716,
        FMT_PKCS8,
        FMT_PEM
} convert_format = FMT_RFC4716;

static char *key_type_name = NULL;

/* Load key from this PKCS#11 provider */
static char *pkcs11provider = NULL;

/* FIDO/U2F provider to use */
static char *sk_provider = NULL;

/* Format for writing private keys */
static int private_key_format = SSHKEY_PRIVATE_OPENSSH;

/* Cipher for new-format private keys */
static char *openssh_format_cipher = NULL;

/* Number of KDF rounds to derive new format keys. */
static int rounds = 0;

/* argv0 */
extern char *__progname;

static char hostname[NI_MAXHOST];

#ifdef WITH_OPENSSL
/* moduli.c */
int gen_candidates(FILE *, u_int32_t, u_int32_t, BIGNUM *);
int prime_test(FILE *, FILE *, u_int32_t, u_int32_t, char *, unsigned long,
    unsigned long);
#endif

static void
type_bits_valid(int type, const char *name, u_int32_t *bitsp)
{
        if (type == KEY_UNSPEC)
                fatal("unknown key type %s", key_type_name);
        if (*bitsp == 0) {
#ifdef WITH_OPENSSL
                int nid;

                switch(type) {
                case KEY_DSA:
                        *bitsp = DEFAULT_BITS_DSA;
                        break;
                case KEY_ECDSA:
                        if (name != NULL &&
                            (nid = sshkey_ecdsa_nid_from_name(name)) > 0)
                                *bitsp = sshkey_curve_nid_to_bits(nid);
                        if (*bitsp == 0)
                                *bitsp = DEFAULT_BITS_ECDSA;
                        break;
                case KEY_RSA:
                        *bitsp = DEFAULT_BITS;
                        break;
                }
#endif
        }
#ifdef WITH_OPENSSL
        switch (type) {
        case KEY_DSA:
                if (*bitsp != 1024)
                        fatal("Invalid DSA key length: must be 1024 bits");
                break;
        case KEY_RSA:
                if (*bitsp < SSH_RSA_MINIMUM_MODULUS_SIZE)
                        fatal("Invalid RSA key length: minimum is %d bits",
                            SSH_RSA_MINIMUM_MODULUS_SIZE);
                else if (*bitsp > OPENSSL_RSA_MAX_MODULUS_BITS)
                        fatal("Invalid RSA key length: maximum is %d bits",
                            OPENSSL_RSA_MAX_MODULUS_BITS);
                break;
        case KEY_ECDSA:
                if (sshkey_ecdsa_bits_to_nid(*bitsp) == -1)
#ifdef OPENSSL_HAS_NISTP521
                        fatal("Invalid ECDSA key length: valid lengths are "
                            "256, 384 or 521 bits");
#else
                        fatal("Invalid ECDSA key length: valid lengths are "
                            "256 or 384 bits");
#endif
        }
#endif
}

/*
 * Checks whether a file exists and, if so, asks the user whether they wish
 * to overwrite it.
 * Returns nonzero if the file does not already exist or if the user agrees to
 * overwrite, or zero otherwise.
 */
static int
confirm_overwrite(const char *filename)
{
        char yesno[3];
        struct stat st;

        if (stat(filename, &st) != 0)
                return 1;
        printf("%s already exists.\n", filename);
        printf("Overwrite (y/n)? ");
        fflush(stdout);
        if (fgets(yesno, sizeof(yesno), stdin) == NULL)
                return 0;
        if (yesno[0] != 'y' && yesno[0] != 'Y')
                return 0;
        return 1;
}

static void
ask_filename(struct passwd *pw, const char *prompt)
{
        char buf[1024];
        char *name = NULL;

        if (key_type_name == NULL)
                name = _PATH_SSH_CLIENT_ID_ED25519;
        else {
                switch (sshkey_type_from_shortname(key_type_name)) {
#ifdef WITH_DSA
                case KEY_DSA_CERT:
                case KEY_DSA:
                        name = _PATH_SSH_CLIENT_ID_DSA;
                        break;
#endif
#ifdef OPENSSL_HAS_ECC
                case KEY_ECDSA_CERT:
                case KEY_ECDSA:
                        name = _PATH_SSH_CLIENT_ID_ECDSA;
                        break;
                case KEY_ECDSA_SK_CERT:
                case KEY_ECDSA_SK:
                        name = _PATH_SSH_CLIENT_ID_ECDSA_SK;
                        break;
#endif
                case KEY_RSA_CERT:
                case KEY_RSA:
                        name = _PATH_SSH_CLIENT_ID_RSA;
                        break;
                case KEY_ED25519:
                case KEY_ED25519_CERT:
                        name = _PATH_SSH_CLIENT_ID_ED25519;
                        break;
                case KEY_ED25519_SK:
                case KEY_ED25519_SK_CERT:
                        name = _PATH_SSH_CLIENT_ID_ED25519_SK;
                        break;
                case KEY_XMSS:
                case KEY_XMSS_CERT:
                        name = _PATH_SSH_CLIENT_ID_XMSS;
                        break;
                default:
                        fatal("bad key type");
                }
        }
        snprintf(identity_file, sizeof(identity_file),
            "%s/%s", pw->pw_dir, name);
        printf("%s (%s): ", prompt, identity_file);
        fflush(stdout);
        if (fgets(buf, sizeof(buf), stdin) == NULL)
                exit(1);
        buf[strcspn(buf, "\n")] = '\0';
        if (strcmp(buf, "") != 0)
                strlcpy(identity_file, buf, sizeof(identity_file));
        have_identity = 1;
}

static struct sshkey *
load_identity(const char *filename, char **commentp)
{
        char *prompt, *pass;
        struct sshkey *prv;
        int r;

        if (commentp != NULL)
                *commentp = NULL;
        if ((r = sshkey_load_private(filename, "", &prv, commentp)) == 0)
                return prv;
        if (r != SSH_ERR_KEY_WRONG_PASSPHRASE)
                fatal_r(r, "Load key \"%s\"", filename);
        if (identity_passphrase)
                pass = xstrdup(identity_passphrase);
        else {
                xasprintf(&prompt, "Enter passphrase for \"%s\": ", filename);
                pass = read_passphrase(prompt, RP_ALLOW_STDIN);
                free(prompt);
        }
        r = sshkey_load_private(filename, pass, &prv, commentp);
        freezero(pass, strlen(pass));
        if (r != 0)
                fatal_r(r, "Load key \"%s\"", filename);
        return prv;
}

#define SSH_COM_PUBLIC_BEGIN            "---- BEGIN SSH2 PUBLIC KEY ----"
#define SSH_COM_PUBLIC_END              "---- END SSH2 PUBLIC KEY ----"
#define SSH_COM_PRIVATE_BEGIN           "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----"
#define SSH_COM_PRIVATE_KEY_MAGIC       0x3f6ff9eb

#ifdef WITH_OPENSSL
static void
do_convert_to_ssh2(struct passwd *pw, struct sshkey *k)
{
        struct sshbuf *b;
        char comment[61], *b64;
        int r;

        if ((b = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshkey_putb(k, b)) != 0)
                fatal_fr(r, "put key");
        if ((b64 = sshbuf_dtob64_string(b, 1)) == NULL)
                fatal_f("sshbuf_dtob64_string failed");

        /* Comment + surrounds must fit into 72 chars (RFC 4716 sec 3.3) */
        snprintf(comment, sizeof(comment),
            "%u-bit %s, converted by %s@%s from OpenSSH",
            sshkey_size(k), sshkey_type(k),
            pw->pw_name, hostname);

        sshkey_free(k);
        sshbuf_free(b);

        fprintf(stdout, "%s\n", SSH_COM_PUBLIC_BEGIN);
        fprintf(stdout, "Comment: \"%s\"\n%s", comment, b64);
        fprintf(stdout, "%s\n", SSH_COM_PUBLIC_END);
        free(b64);
        exit(0);
}

static void
do_convert_to_pkcs8(struct sshkey *k)
{
        switch (sshkey_type_plain(k->type)) {
        case KEY_RSA:
                if (!PEM_write_RSA_PUBKEY(stdout,
                    EVP_PKEY_get0_RSA(k->pkey)))
                        fatal("PEM_write_RSA_PUBKEY failed");
                break;
#ifdef WITH_DSA
        case KEY_DSA:
                if (!PEM_write_DSA_PUBKEY(stdout, k->dsa))
                        fatal("PEM_write_DSA_PUBKEY failed");
                break;
#endif
#ifdef OPENSSL_HAS_ECC
        case KEY_ECDSA:
                if (!PEM_write_EC_PUBKEY(stdout,
                    EVP_PKEY_get0_EC_KEY(k->pkey)))
                        fatal("PEM_write_EC_PUBKEY failed");
                break;
#endif
        default:
                fatal_f("unsupported key type %s", sshkey_type(k));
        }
        exit(0);
}

static void
do_convert_to_pem(struct sshkey *k)
{
        switch (sshkey_type_plain(k->type)) {
        case KEY_RSA:
                if (!PEM_write_RSAPublicKey(stdout,
                    EVP_PKEY_get0_RSA(k->pkey)))
                        fatal("PEM_write_RSAPublicKey failed");
                break;
#ifdef WITH_DSA
        case KEY_DSA:
                if (!PEM_write_DSA_PUBKEY(stdout, k->dsa))
                        fatal("PEM_write_DSA_PUBKEY failed");
                break;
#endif
#ifdef OPENSSL_HAS_ECC
        case KEY_ECDSA:
                if (!PEM_write_EC_PUBKEY(stdout,
                    EVP_PKEY_get0_EC_KEY(k->pkey)))
                        fatal("PEM_write_EC_PUBKEY failed");
                break;
#endif
        default:
                fatal_f("unsupported key type %s", sshkey_type(k));
        }
        exit(0);
}

static void
do_convert_to(struct passwd *pw)
{
        struct sshkey *k;
        struct stat st;
        int r;

        if (!have_identity)
                ask_filename(pw, "Enter file in which the key is");
        if (stat(identity_file, &st) == -1)
                fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
        if ((r = sshkey_load_public(identity_file, &k, NULL)) != 0)
                k = load_identity(identity_file, NULL);
        switch (convert_format) {
        case FMT_RFC4716:
                do_convert_to_ssh2(pw, k);
                break;
        case FMT_PKCS8:
                do_convert_to_pkcs8(k);
                break;
        case FMT_PEM:
                do_convert_to_pem(k);
                break;
        default:
                fatal_f("unknown key format %d", convert_format);
        }
        exit(0);
}

/*
 * This is almost exactly the bignum1 encoding, but with 32 bit for length
 * instead of 16.
 */
static void
buffer_get_bignum_bits(struct sshbuf *b, BIGNUM *value)
{
        u_int bytes, bignum_bits;
        int r;

        if ((r = sshbuf_get_u32(b, &bignum_bits)) != 0)
                fatal_fr(r, "parse");
        bytes = (bignum_bits + 7) / 8;
        if (sshbuf_len(b) < bytes)
                fatal_f("input buffer too small: need %d have %zu",
                    bytes, sshbuf_len(b));
        if (BN_bin2bn(sshbuf_ptr(b), bytes, value) == NULL)
                fatal_f("BN_bin2bn failed");
        if ((r = sshbuf_consume(b, bytes)) != 0)
                fatal_fr(r, "consume");
}

static struct sshkey *
do_convert_private_ssh2(struct sshbuf *b)
{
        struct sshkey *key = NULL;
        char *type, *cipher;
        const char *alg = NULL;
        u_char e1, e2, e3, *sig = NULL, data[] = "abcde12345";
        int r, rlen, ktype;
        u_int magic, i1, i2, i3, i4;
        size_t slen;
        u_long e;
#ifdef WITH_DSA
        BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL;
        BIGNUM *dsa_pub_key = NULL, *dsa_priv_key = NULL;
#endif
        BIGNUM *rsa_n = NULL, *rsa_e = NULL, *rsa_d = NULL;
        BIGNUM *rsa_p = NULL, *rsa_q = NULL, *rsa_iqmp = NULL;
        BIGNUM *rsa_dmp1 = NULL, *rsa_dmq1 = NULL;
        RSA *rsa = NULL;

        if ((r = sshbuf_get_u32(b, &magic)) != 0)
                fatal_fr(r, "parse magic");

        if (magic != SSH_COM_PRIVATE_KEY_MAGIC) {
                error("bad magic 0x%x != 0x%x", magic,
                    SSH_COM_PRIVATE_KEY_MAGIC);
                return NULL;
        }
        if ((r = sshbuf_get_u32(b, &i1)) != 0 ||
            (r = sshbuf_get_cstring(b, &type, NULL)) != 0 ||
            (r = sshbuf_get_cstring(b, &cipher, NULL)) != 0 ||
            (r = sshbuf_get_u32(b, &i2)) != 0 ||
            (r = sshbuf_get_u32(b, &i3)) != 0 ||
            (r = sshbuf_get_u32(b, &i4)) != 0)
                fatal_fr(r, "parse");
        debug("ignore (%d %d %d %d)", i1, i2, i3, i4);
        if (strcmp(cipher, "none") != 0) {
                error("unsupported cipher %s", cipher);
                free(cipher);
                free(type);
                return NULL;
        }
        free(cipher);

        if (strstr(type, "rsa")) {
                ktype = KEY_RSA;
#ifdef WITH_DSA
        } else if (strstr(type, "dsa")) {
                ktype = KEY_DSA;
#endif
        } else {
                free(type);
                return NULL;
        }
        if ((key = sshkey_new(ktype)) == NULL)
                fatal("sshkey_new failed");
        free(type);

        switch (key->type) {
#ifdef WITH_DSA
        case KEY_DSA:
                if ((dsa_p = BN_new()) == NULL ||
                    (dsa_q = BN_new()) == NULL ||
                    (dsa_g = BN_new()) == NULL ||
                    (dsa_pub_key = BN_new()) == NULL ||
                    (dsa_priv_key = BN_new()) == NULL)
                        fatal_f("BN_new");
                buffer_get_bignum_bits(b, dsa_p);
                buffer_get_bignum_bits(b, dsa_g);
                buffer_get_bignum_bits(b, dsa_q);
                buffer_get_bignum_bits(b, dsa_pub_key);
                buffer_get_bignum_bits(b, dsa_priv_key);
                if (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g))
                        fatal_f("DSA_set0_pqg failed");
                dsa_p = dsa_q = dsa_g = NULL; /* transferred */
                if (!DSA_set0_key(key->dsa, dsa_pub_key, dsa_priv_key))
                        fatal_f("DSA_set0_key failed");
                dsa_pub_key = dsa_priv_key = NULL; /* transferred */
                break;
#endif
        case KEY_RSA:
                if ((r = sshbuf_get_u8(b, &e1)) != 0 ||
                    (e1 < 30 && (r = sshbuf_get_u8(b, &e2)) != 0) ||
                    (e1 < 30 && (r = sshbuf_get_u8(b, &e3)) != 0))
                        fatal_fr(r, "parse RSA");
                e = e1;
                debug("e %lx", e);
                if (e < 30) {
                        e <<= 8;
                        e += e2;
                        debug("e %lx", e);
                        e <<= 8;
                        e += e3;
                        debug("e %lx", e);
                }
                if ((rsa_e = BN_new()) == NULL)
                        fatal_f("BN_new");
                if (!BN_set_word(rsa_e, e)) {
                        BN_clear_free(rsa_e);
                        sshkey_free(key);
                        return NULL;
                }
                if ((rsa_n = BN_new()) == NULL ||
                    (rsa_d = BN_new()) == NULL ||
                    (rsa_p = BN_new()) == NULL ||
                    (rsa_q = BN_new()) == NULL ||
                    (rsa_iqmp = BN_new()) == NULL)
                        fatal_f("BN_new");
                buffer_get_bignum_bits(b, rsa_d);
                buffer_get_bignum_bits(b, rsa_n);
                buffer_get_bignum_bits(b, rsa_iqmp);
                buffer_get_bignum_bits(b, rsa_q);
                buffer_get_bignum_bits(b, rsa_p);
                if ((r = ssh_rsa_complete_crt_parameters(rsa_d, rsa_p, rsa_q,
                    rsa_iqmp, &rsa_dmp1, &rsa_dmq1)) != 0)
                        fatal_fr(r, "generate RSA CRT parameters");
                if ((key->pkey = EVP_PKEY_new()) == NULL)
                        fatal_f("EVP_PKEY_new failed");
                if ((rsa = RSA_new()) == NULL)
                        fatal_f("RSA_new failed");
                if (!RSA_set0_key(rsa, rsa_n, rsa_e, rsa_d))
                        fatal_f("RSA_set0_key failed");
                rsa_n = rsa_e = rsa_d = NULL; /* transferred */
                if (!RSA_set0_factors(rsa, rsa_p, rsa_q))
                        fatal_f("RSA_set0_factors failed");
                rsa_p = rsa_q = NULL; /* transferred */
                if (RSA_set0_crt_params(rsa, rsa_dmp1, rsa_dmq1, rsa_iqmp) != 1)
                        fatal_f("RSA_set0_crt_params failed");
                rsa_dmp1 = rsa_dmq1 = rsa_iqmp = NULL;
                if (EVP_PKEY_set1_RSA(key->pkey, rsa) != 1)
                        fatal_f("EVP_PKEY_set1_RSA failed");
                RSA_free(rsa);
                alg = "rsa-sha2-256";
                break;
        }
        rlen = sshbuf_len(b);
        if (rlen != 0)
                error_f("remaining bytes in key blob %d", rlen);

        /* try the key */
        if ((r = sshkey_sign(key, &sig, &slen, data, sizeof(data),
            alg, NULL, NULL, 0)) != 0)
                error_fr(r, "signing with converted key failed");
        else if ((r = sshkey_verify(key, sig, slen, data, sizeof(data),
            alg, 0, NULL)) != 0)
                error_fr(r, "verification with converted key failed");
        if (r != 0) {
                sshkey_free(key);
                free(sig);
                return NULL;
        }
        free(sig);
        return key;
}

static int
get_line(FILE *fp, char *line, size_t len)
{
        int c;
        size_t pos = 0;

        line[0] = '\0';
        while ((c = fgetc(fp)) != EOF) {
                if (pos >= len - 1)
                        fatal("input line too long.");
                switch (c) {
                case '\r':
                        c = fgetc(fp);
                        if (c != EOF && c != '\n' && ungetc(c, fp) == EOF)
                                fatal("unget: %s", strerror(errno));
                        return pos;
                case '\n':
                        return pos;
                }
                line[pos++] = c;
                line[pos] = '\0';
        }
        /* We reached EOF */
        return -1;
}

static void
do_convert_from_ssh2(struct passwd *pw, struct sshkey **k, int *private)
{
        int r, blen, escaped = 0;
        u_int len;
        char line[1024];
        struct sshbuf *buf;
        char encoded[8096];
        FILE *fp;

        if ((buf = sshbuf_new()) == NULL)
                fatal("sshbuf_new failed");
        if ((fp = fopen(identity_file, "r")) == NULL)
                fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
        encoded[0] = '\0';
        while ((blen = get_line(fp, line, sizeof(line))) != -1) {
                if (blen > 0 && line[blen - 1] == '\\')
                        escaped++;
                if (strncmp(line, "----", 4) == 0 ||
                    strstr(line, ": ") != NULL) {
                        if (strstr(line, SSH_COM_PRIVATE_BEGIN) != NULL)
                                *private = 1;
                        if (strstr(line, " END ") != NULL) {
                                break;
                        }
                        /* fprintf(stderr, "ignore: %s", line); */
                        continue;
                }
                if (escaped) {
                        escaped--;
                        /* fprintf(stderr, "escaped: %s", line); */
                        continue;
                }
                strlcat(encoded, line, sizeof(encoded));
        }
        len = strlen(encoded);
        if (((len % 4) == 3) &&
            (encoded[len-1] == '=') &&
            (encoded[len-2] == '=') &&
            (encoded[len-3] == '='))
                encoded[len-3] = '\0';
        if ((r = sshbuf_b64tod(buf, encoded)) != 0)
                fatal_fr(r, "base64 decode");
        if (*private) {
                if ((*k = do_convert_private_ssh2(buf)) == NULL)
                        fatal_f("private key conversion failed");
        } else if ((r = sshkey_fromb(buf, k)) != 0)
                fatal_fr(r, "parse key");
        sshbuf_free(buf);
        fclose(fp);
}

static void
do_convert_from_pkcs8(struct sshkey **k, int *private)
{
        EVP_PKEY *pubkey;
        FILE *fp;

        if ((fp = fopen(identity_file, "r")) == NULL)
                fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
        if ((pubkey = PEM_read_PUBKEY(fp, NULL, NULL, NULL)) == NULL) {
                fatal_f("%s is not a recognised public key format",
                    identity_file);
        }
        fclose(fp);
        switch (EVP_PKEY_base_id(pubkey)) {
        case EVP_PKEY_RSA:
                if ((*k = sshkey_new(KEY_UNSPEC)) == NULL)
                        fatal("sshkey_new failed");
                (*k)->type = KEY_RSA;
                (*k)->pkey = pubkey;
                pubkey = NULL;
                break;
#ifdef WITH_DSA
        case EVP_PKEY_DSA:
                if ((*k = sshkey_new(KEY_UNSPEC)) == NULL)
                        fatal("sshkey_new failed");
                (*k)->type = KEY_DSA;
                (*k)->dsa = EVP_PKEY_get1_DSA(pubkey);
                break;
#endif
#ifdef OPENSSL_HAS_ECC
        case EVP_PKEY_EC:
                if ((*k = sshkey_new(KEY_UNSPEC)) == NULL)
                        fatal("sshkey_new failed");
                if (((*k)->ecdsa_nid = sshkey_ecdsa_fixup_group(pubkey)) == -1)
                        fatal("sshkey_ecdsa_fixup_group failed");
                (*k)->type = KEY_ECDSA;
                (*k)->pkey = pubkey;
                pubkey = NULL;
                break;
#endif
        default:
                fatal_f("unsupported pubkey type %d",
                    EVP_PKEY_base_id(pubkey));
        }
        EVP_PKEY_free(pubkey);
        return;
}

static void
do_convert_from_pem(struct sshkey **k, int *private)
{
        FILE *fp;
        RSA *rsa;

        if ((fp = fopen(identity_file, "r")) == NULL)
                fatal("%s: %s: %s", __progname, identity_file, strerror(errno));
        if ((rsa = PEM_read_RSAPublicKey(fp, NULL, NULL, NULL)) != NULL) {
                if ((*k = sshkey_new(KEY_UNSPEC)) == NULL)
                        fatal("sshkey_new failed");
                if (((*k)->pkey = EVP_PKEY_new()) == NULL)
                        fatal("EVP_PKEY_new failed");
                (*k)->type = KEY_RSA;
                if (EVP_PKEY_set1_RSA((*k)->pkey, rsa) != 1)
                        fatal("EVP_PKEY_set1_RSA failed");
                RSA_free(rsa);
                fclose(fp);
                return;
        }
        fatal_f("unrecognised raw private key format");
}

static void
do_convert_from(struct passwd *pw)
{
        struct sshkey *k = NULL;
        int r, private = 0, ok = 0;
        struct stat st;

        if (!have_identity)
                ask_filename(pw, "Enter file in which the key is");
        if (stat(identity_file, &st) == -1)
                fatal("%s: %s: %s", __progname, identity_file, strerror(errno));

        switch (convert_format) {
        case FMT_RFC4716:
                do_convert_from_ssh2(pw, &k, &private);
                break;
        case FMT_PKCS8:
                do_convert_from_pkcs8(&k, &private);
                break;
        case FMT_PEM:
                do_convert_from_pem(&k, &private);
                break;
        default:
                fatal_f("unknown key format %d", convert_format);
        }

        if (!private) {
                if ((r = sshkey_write(k, stdout)) == 0)
                        ok = 1;
                if (ok)
                        fprintf(stdout, "\n");
        } else {
                switch (k->type) {
#ifdef WITH_DSA
                case KEY_DSA:
                        ok = PEM_write_DSAPrivateKey(stdout, k->dsa, NULL,
                            NULL, 0, NULL, NULL);
                        break;
#endif
#ifdef OPENSSL_HAS_ECC
                case KEY_ECDSA:
                        ok = PEM_write_ECPrivateKey(stdout,
                            EVP_PKEY_get0_EC_KEY(k->pkey), NULL, NULL, 0,
                            NULL, NULL);
                        break;
#endif
                case KEY_RSA:
                        ok = PEM_write_RSAPrivateKey(stdout,
                            EVP_PKEY_get0_RSA(k->pkey), NULL, NULL, 0,
                            NULL, NULL);
                        break;
                default:
                        fatal_f("unsupported key type %s", sshkey_type(k));
                }
        }

        if (!ok)
                fatal("key write failed");
        sshkey_free(k);
        exit(0);
}
#endif

static void
do_print_public(struct passwd *pw)
{
        struct sshkey *prv;
        struct stat st;
        int r;
        char *comment = NULL;

        if (!have_identity)
                ask_filename(pw, "Enter file in which the key is");
        if (stat(identity_file, &st) == -1)
                fatal("%s: %s", identity_file, strerror(errno));
        prv = load_identity(identity_file, &comment);
        if ((r = sshkey_write(prv, stdout)) != 0)
                fatal_fr(r, "write key");
        if (comment != NULL && *comment != '\0')
                fprintf(stdout, " %s", comment);
        fprintf(stdout, "\n");
        if (sshkey_is_sk(prv)) {
                debug("sk_application: \"%s\", sk_flags 0x%02x",
                        prv->sk_application, prv->sk_flags);
        }
        sshkey_free(prv);
        free(comment);
        exit(0);
}

static void
do_download(struct passwd *pw)
{
#ifdef ENABLE_PKCS11
        struct sshkey **keys = NULL;
        int i, nkeys;
        enum sshkey_fp_rep rep;
        int fptype;
        char *fp, *ra, **comments = NULL;

        fptype = print_bubblebabble ? SSH_DIGEST_SHA1 : fingerprint_hash;
        rep =    print_bubblebabble ? SSH_FP_BUBBLEBABBLE : SSH_FP_DEFAULT;

        pkcs11_init(1);
        nkeys = pkcs11_add_provider(pkcs11provider, NULL, &keys, &comments);
        if (nkeys <= 0)
                fatal("cannot read public key from pkcs11");
        for (i = 0; i < nkeys; i++) {
                if (print_fingerprint) {
                        fp = sshkey_fingerprint(keys[i], fptype, rep);
                        ra = sshkey_fingerprint(keys[i], fingerprint_hash,
                            SSH_FP_RANDOMART);
                        if (fp == NULL || ra == NULL)
                                fatal_f("sshkey_fingerprint fail");
                        printf("%u %s %s (PKCS11 key)\n", sshkey_size(keys[i]),
                            fp, sshkey_type(keys[i]));
                        if (log_level_get() >= SYSLOG_LEVEL_VERBOSE)
                                printf("%s\n", ra);
                        free(ra);
                        free(fp);
                } else {
                        (void) sshkey_write(keys[i], stdout); /* XXX check */
                        fprintf(stdout, "%s%s\n",
                            *(comments[i]) == '\0' ? "" : " ", comments[i]);
                }
                free(comments[i]);
                sshkey_free(keys[i]);
        }
        free(comments);
        free(keys);
        pkcs11_terminate();
        exit(0);
#else
        fatal("no pkcs11 support");
#endif /* ENABLE_PKCS11 */
}

static struct sshkey *
try_read_key(char **cpp)
{
        struct sshkey *ret;
        int r;

        if ((ret = sshkey_new(KEY_UNSPEC)) == NULL)
                fatal("sshkey_new failed");
        if ((r = sshkey_read(ret, cpp)) == 0)
                return ret;
        /* Not a key */
        sshkey_free(ret);
        return NULL;
}

static void
fingerprint_one_key(const struct sshkey *public, const char *comment)
{
        char *fp = NULL, *ra = NULL;
        enum sshkey_fp_rep rep;
        int fptype;

        fptype = print_bubblebabble ? SSH_DIGEST_SHA1 : fingerprint_hash;
        rep =    print_bubblebabble ? SSH_FP_BUBBLEBABBLE : SSH_FP_DEFAULT;
        fp = sshkey_fingerprint(public, fptype, rep);
        ra = sshkey_fingerprint(public, fingerprint_hash, SSH_FP_RANDOMART);
        if (fp == NULL || ra == NULL)
                fatal_f("sshkey_fingerprint failed");
        mprintf("%u %s %s (%s)\n", sshkey_size(public), fp,
            comment ? comment : "no comment", sshkey_type(public));
        if (log_level_get() >= SYSLOG_LEVEL_VERBOSE)
                printf("%s\n", ra);
        free(ra);
        free(fp);
}

static void
fingerprint_private(const char *path)
{
        struct stat st;
        char *comment = NULL;
        struct sshkey *privkey = NULL, *pubkey = NULL;
        int r;

        if (stat(identity_file, &st) == -1)
                fatal("%s: %s", path, strerror(errno));
        if ((r = sshkey_load_public(path, &pubkey, &comment)) != 0)
                debug_r(r, "load public \"%s\"", path);
        if (pubkey == NULL || comment == NULL || *comment == '\0') {
                free(comment);
                if ((r = sshkey_load_private(path, NULL,
                    &privkey, &comment)) != 0)
                        debug_r(r, "load private \"%s\"", path);
        }
        if (pubkey == NULL && privkey == NULL)
                fatal("%s is not a key file.", path);

        fingerprint_one_key(pubkey == NULL ? privkey : pubkey, comment);
        sshkey_free(pubkey);
        sshkey_free(privkey);
        free(comment);
}

static void
do_fingerprint(struct passwd *pw)
{
        FILE *f;
        struct sshkey *public = NULL;
        char *comment = NULL, *cp, *ep, *line = NULL;
        size_t linesize = 0;
        int i, invalid = 1;
        const char *path;
        u_long lnum = 0;

        if (!have_identity)
                ask_filename(pw, "Enter file in which the key is");
        path = identity_file;

        if (strcmp(identity_file, "-") == 0) {
                f = stdin;
                path = "(stdin)";
        } else if ((f = fopen(path, "r")) == NULL)
                fatal("%s: %s: %s", __progname, path, strerror(errno));

        while (getline(&line, &linesize, f) != -1) {
                lnum++;
                cp = line;
                cp[strcspn(cp, "\r\n")] = '\0';
                /* Trim leading space and comments */
                cp = line + strspn(line, " \t");
                if (*cp == '#' || *cp == '\0')
                        continue;

                /*
                 * Input may be plain keys, private keys, authorized_keys
                 * or known_hosts.
                 */

                /*
                 * Try private keys first. Assume a key is private if
                 * "SSH PRIVATE KEY" appears on the first line and we're
                 * not reading from stdin (XXX support private keys on stdin).
                 */
                if (lnum == 1 && strcmp(identity_file, "-") != 0 &&
                    strstr(cp, "PRIVATE KEY") != NULL) {
                        free(line);
                        fclose(f);
                        fingerprint_private(path);
                        exit(0);
                }

                /*
                 * If it's not a private key, then this must be prepared to
                 * accept a public key prefixed with a hostname or options.
                 * Try a bare key first, otherwise skip the leading stuff.
                 */
                comment = NULL;
                if ((public = try_read_key(&cp)) == NULL) {
                        i = strtol(cp, &ep, 10);
                        if (i == 0 || ep == NULL ||
                            (*ep != ' ' && *ep != '\t')) {
                                int quoted = 0;

                                comment = cp;
                                for (; *cp && (quoted || (*cp != ' ' &&
                                    *cp != '\t')); cp++) {
                                        if (*cp == '\\' && cp[1] == '"')
                                                cp++;   /* Skip both */
                                        else if (*cp == '"')
                                                quoted = !quoted;
                                }
                                if (!*cp)
                                        continue;
                                *cp++ = '\0';
                        }
                }
                /* Retry after parsing leading hostname/key options */
                if (public == NULL && (public = try_read_key(&cp)) == NULL) {
                        debug("%s:%lu: not a public key", path, lnum);
                        continue;
                }

                /* Find trailing comment, if any */
                for (; *cp == ' ' || *cp == '\t'; cp++)
                        ;
                if (*cp != '\0' && *cp != '#')
                        comment = cp;

                fingerprint_one_key(public, comment);
                sshkey_free(public);
                invalid = 0; /* One good key in the file is sufficient */
        }
        fclose(f);
        free(line);

        if (invalid)
                fatal("%s is not a public key file.", path);
        exit(0);
}

static void
do_gen_all_hostkeys(struct passwd *pw)
{
        struct {
                char *key_type;
                char *key_type_display;
                char *path;
        } key_types[] = {
#ifdef WITH_OPENSSL
                { "rsa", "RSA" ,_PATH_HOST_RSA_KEY_FILE },
#ifdef OPENSSL_HAS_ECC
                { "ecdsa", "ECDSA",_PATH_HOST_ECDSA_KEY_FILE },
#endif /* OPENSSL_HAS_ECC */
#endif /* WITH_OPENSSL */
                { "ed25519", "ED25519",_PATH_HOST_ED25519_KEY_FILE },
#ifdef WITH_XMSS
                { "xmss", "XMSS",_PATH_HOST_XMSS_KEY_FILE },
#endif /* WITH_XMSS */
                { NULL, NULL, NULL }
        };

        u_int32_t bits = 0;
        int first = 0;
        struct stat st;
        struct sshkey *private, *public;
        char comment[1024], *prv_tmp, *pub_tmp, *prv_file, *pub_file;
        int i, type, fd, r;

        for (i = 0; key_types[i].key_type; i++) {
                public = private = NULL;
                prv_tmp = pub_tmp = prv_file = pub_file = NULL;

                xasprintf(&prv_file, "%s%s",
                    identity_file, key_types[i].path);

                /* Check whether private key exists and is not zero-length */
                if (stat(prv_file, &st) == 0) {
                        if (st.st_size != 0)
                                goto next;
                } else if (errno != ENOENT) {
                        error("Could not stat %s: %s", key_types[i].path,
                            strerror(errno));
                        goto failnext;
                }

                /*
                 * Private key doesn't exist or is invalid; proceed with
                 * key generation.
                 */
                xasprintf(&prv_tmp, "%s%s.XXXXXXXXXX",
                    identity_file, key_types[i].path);
                xasprintf(&pub_tmp, "%s%s.pub.XXXXXXXXXX",
                    identity_file, key_types[i].path);
                xasprintf(&pub_file, "%s%s.pub",
                    identity_file, key_types[i].path);

                if (first == 0) {
                        first = 1;
                        printf("%s: generating new host keys: ", __progname);
                }
                printf("%s ", key_types[i].key_type_display);
                fflush(stdout);
                type = sshkey_type_from_shortname(key_types[i].key_type);
                if ((fd = mkstemp(prv_tmp)) == -1) {
                        error("Could not save your private key in %s: %s",
                            prv_tmp, strerror(errno));
                        goto failnext;
                }
                (void)close(fd); /* just using mkstemp() to reserve a name */
                bits = 0;
                type_bits_valid(type, NULL, &bits);
                if ((r = sshkey_generate(type, bits, &private)) != 0) {
                        error_r(r, "sshkey_generate failed");
                        goto failnext;
                }
                if ((r = sshkey_from_private(private, &public)) != 0)
                        fatal_fr(r, "sshkey_from_private");
                snprintf(comment, sizeof comment, "%s@%s", pw->pw_name,
                    hostname);
                if ((r = sshkey_save_private(private, prv_tmp, "",
                    comment, private_key_format, openssh_format_cipher,
                    rounds)) != 0) {
                        error_r(r, "Saving key \"%s\" failed", prv_tmp);
                        goto failnext;
                }
                if ((fd = mkstemp(pub_tmp)) == -1) {
                        error("Could not save your public key in %s: %s",
                            pub_tmp, strerror(errno));
                        goto failnext;
                }
                (void)fchmod(fd, 0644);
                (void)close(fd);
                if ((r = sshkey_save_public(public, pub_tmp, comment)) != 0) {
                        error_r(r, "Unable to save public key to %s",
                            identity_file);
                        goto failnext;
                }

                /* Rename temporary files to their permanent locations. */
                if (rename(pub_tmp, pub_file) != 0) {
                        error("Unable to move %s into position: %s",
                            pub_file, strerror(errno));
                        goto failnext;
                }
                if (rename(prv_tmp, prv_file) != 0) {
                        error("Unable to move %s into position: %s",
                            key_types[i].path, strerror(errno));
 failnext:
                        first = 0;
                        goto next;
                }
 next:
                sshkey_free(private);
                sshkey_free(public);
                free(prv_tmp);
                free(pub_tmp);
                free(prv_file);
                free(pub_file);
        }
        if (first != 0)
                printf("\n");
}

struct known_hosts_ctx {
        const char *host;       /* Hostname searched for in find/delete case */
        FILE *out;              /* Output file, stdout for find_hosts case */
        int has_unhashed;       /* When hashing, original had unhashed hosts */
        int found_key;          /* For find/delete, host was found */
        int invalid;            /* File contained invalid items; don't delete */
        int hash_hosts;         /* Hash hostnames as we go */
        int find_host;          /* Search for specific hostname */
        int delete_host;        /* Delete host from known_hosts */
};

static int
known_hosts_hash(struct hostkey_foreach_line *l, void *_ctx)
{
        struct known_hosts_ctx *ctx = (struct known_hosts_ctx *)_ctx;
        char *hashed, *cp, *hosts, *ohosts;
        int has_wild = l->hosts && strcspn(l->hosts, "*?!") != strlen(l->hosts);
        int was_hashed = l->hosts && l->hosts[0] == HASH_DELIM;

        switch (l->status) {
        case HKF_STATUS_OK:
        case HKF_STATUS_MATCHED:
                /*
                 * Don't hash hosts already hashed, with wildcard
                 * characters or a CA/revocation marker.
                 */
                if (was_hashed || has_wild || l->marker != MRK_NONE) {
                        fprintf(ctx->out, "%s\n", l->line);
                        if (has_wild && !ctx->find_host) {
                                logit("%s:%lu: ignoring host name "
                                    "with wildcard: %.64s", l->path,
                                    l->linenum, l->hosts);
                        }
                        return 0;
                }
                /*
                 * Split any comma-separated hostnames from the host list,
                 * hash and store separately.
                 */
                ohosts = hosts = xstrdup(l->hosts);
                while ((cp = strsep(&hosts, ",")) != NULL && *cp != '\0') {
                        lowercase(cp);
                        if ((hashed = host_hash(cp, NULL, 0)) == NULL)
                                fatal("hash_host failed");
                        fprintf(ctx->out, "%s %s\n", hashed, l->rawkey);
                        free(hashed);
                        ctx->has_unhashed = 1;
                }
                free(ohosts);
                return 0;
        case HKF_STATUS_INVALID:
                /* Retain invalid lines, but mark file as invalid. */
                ctx->invalid = 1;
                logit("%s:%lu: invalid line", l->path, l->linenum);
                /* FALLTHROUGH */
        default:
                fprintf(ctx->out, "%s\n", l->line);
                return 0;
        }
        /* NOTREACHED */
        return -1;
}

static int
known_hosts_find_delete(struct hostkey_foreach_line *l, void *_ctx)
{
        struct known_hosts_ctx *ctx = (struct known_hosts_ctx *)_ctx;
        enum sshkey_fp_rep rep;
        int fptype;
        char *fp = NULL, *ra = NULL;

        fptype = print_bubblebabble ? SSH_DIGEST_SHA1 : fingerprint_hash;
        rep =    print_bubblebabble ? SSH_FP_BUBBLEBABBLE : SSH_FP_DEFAULT;

        if (l->status == HKF_STATUS_MATCHED) {
                if (ctx->delete_host) {
                        if (l->marker != MRK_NONE) {
                                /* Don't remove CA and revocation lines */
                                fprintf(ctx->out, "%s\n", l->line);
                        } else {
                                /*
                                 * Hostname matches and has no CA/revoke
                                 * marker, delete it by *not* writing the
                                 * line to ctx->out.
                                 */
                                ctx->found_key = 1;
                                if (!quiet)
                                        printf("# Host %s found: line %lu\n",
                                            ctx->host, l->linenum);
                        }
                        return 0;
                } else if (ctx->find_host) {
                        ctx->found_key = 1;
                        if (!quiet) {
                                printf("# Host %s found: line %lu %s\n",
                                    ctx->host,
                                    l->linenum, l->marker == MRK_CA ? "CA" :
                                    (l->marker == MRK_REVOKE ? "REVOKED" : ""));
                        }
                        if (ctx->hash_hosts)
                                known_hosts_hash(l, ctx);
                        else if (print_fingerprint) {
                                fp = sshkey_fingerprint(l->key, fptype, rep);
                                ra = sshkey_fingerprint(l->key,
                                    fingerprint_hash, SSH_FP_RANDOMART);
                                if (fp == NULL || ra == NULL)
                                        fatal_f("sshkey_fingerprint failed");
                                mprintf("%s %s %s%s%s\n", ctx->host,
                                    sshkey_type(l->key), fp,
                                    l->comment[0] ? " " : "",
                                    l->comment);
                                if (log_level_get() >= SYSLOG_LEVEL_VERBOSE)
                                        printf("%s\n", ra);
                                free(ra);
                                free(fp);
                        } else
                                fprintf(ctx->out, "%s\n", l->line);
                        return 0;
                }
        } else if (ctx->delete_host) {
                /* Retain non-matching hosts when deleting */
                if (l->status == HKF_STATUS_INVALID) {
                        ctx->invalid = 1;
                        logit("%s:%lu: invalid line", l->path, l->linenum);
                }
                fprintf(ctx->out, "%s\n", l->line);
        }
        return 0;
}

static void
do_known_hosts(struct passwd *pw, const char *name, int find_host,
    int delete_host, int hash_hosts)
{
        char *cp, tmp[PATH_MAX], old[PATH_MAX];
        int r, fd, oerrno, inplace = 0;
        struct known_hosts_ctx ctx;
        u_int foreach_options;
        struct stat sb;

        if (!have_identity) {
                cp = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid);
                if (strlcpy(identity_file, cp, sizeof(identity_file)) >=
                    sizeof(identity_file))
                        fatal("Specified known hosts path too long");
                free(cp);
                have_identity = 1;
        }
        if (stat(identity_file, &sb) != 0)
                fatal("Cannot stat %s: %s", identity_file, strerror(errno));

        memset(&ctx, 0, sizeof(ctx));
        ctx.out = stdout;
        ctx.host = name;
        ctx.hash_hosts = hash_hosts;
        ctx.find_host = find_host;
        ctx.delete_host = delete_host;

        /*
         * Find hosts goes to stdout, hash and deletions happen in-place
         * A corner case is ssh-keygen -HF foo, which should go to stdout
         */
        if (!find_host && (hash_hosts || delete_host)) {
                if (strlcpy(tmp, identity_file, sizeof(tmp)) >= sizeof(tmp) ||
                    strlcat(tmp, ".XXXXXXXXXX", sizeof(tmp)) >= sizeof(tmp) ||
                    strlcpy(old, identity_file, sizeof(old)) >= sizeof(old) ||
                    strlcat(old, ".old", sizeof(old)) >= sizeof(old))
                        fatal("known_hosts path too long");
                umask(077);
                if ((fd = mkstemp(tmp)) == -1)
                        fatal("mkstemp: %s", strerror(errno));
                if ((ctx.out = fdopen(fd, "w")) == NULL) {
                        oerrno = errno;
                        unlink(tmp);
                        fatal("fdopen: %s", strerror(oerrno));
                }
                (void)fchmod(fd, sb.st_mode & 0644);
                inplace = 1;
        }
        /* XXX support identity_file == "-" for stdin */
        foreach_options = find_host ? HKF_WANT_MATCH : 0;
        foreach_options |= print_fingerprint ? HKF_WANT_PARSE_KEY : 0;
        if ((r = hostkeys_foreach(identity_file, (find_host || !hash_hosts) ?
            known_hosts_find_delete : known_hosts_hash, &ctx, name, NULL,
            foreach_options, 0)) != 0) {
                if (inplace)
                        unlink(tmp);
                fatal_fr(r, "hostkeys_foreach");
        }

        if (inplace)
                fclose(ctx.out);

        if (ctx.invalid) {
                error("%s is not a valid known_hosts file.", identity_file);
                if (inplace) {
                        error("Not replacing existing known_hosts "
                            "file because of errors");
                        unlink(tmp);
                }
                exit(1);
        } else if (delete_host && !ctx.found_key) {
                logit("Host %s not found in %s", name, identity_file);
                if (inplace)
                        unlink(tmp);
        } else if (inplace) {
                /* Backup existing file */
                if (unlink(old) == -1 && errno != ENOENT)
                        fatal("unlink %.100s: %s", old, strerror(errno));
                if (link(identity_file, old) == -1)
                        fatal("link %.100s to %.100s: %s", identity_file, old,
                            strerror(errno));
                /* Move new one into place */
                if (rename(tmp, identity_file) == -1) {
                        error("rename\"%s\" to \"%s\": %s", tmp, identity_file,
                            strerror(errno));
                        unlink(tmp);
                        unlink(old);
                        exit(1);
                }

                printf("%s updated.\n", identity_file);
                printf("Original contents retained as %s\n", old);
                if (ctx.has_unhashed) {
                        logit("WARNING: %s contains unhashed entries", old);
                        logit("Delete this file to ensure privacy "
                            "of hostnames");
                }
        }

        exit (find_host && !ctx.found_key);
}

/*
 * Perform changing a passphrase.  The argument is the passwd structure
 * for the current user.
 */
static void
do_change_passphrase(struct passwd *pw)
{
        char *comment;
        char *old_passphrase, *passphrase1, *passphrase2;
        struct stat st;
        struct sshkey *private;
        int r;

        if (!have_identity)
                ask_filename(pw, "Enter file in which the key is");
        if (stat(identity_file, &st) == -1)
                fatal("%s: %s", identity_file, strerror(errno));
        /* Try to load the file with empty passphrase. */
        r = sshkey_load_private(identity_file, "", &private, &comment);
        if (r == SSH_ERR_KEY_WRONG_PASSPHRASE) {
                if (identity_passphrase)
                        old_passphrase = xstrdup(identity_passphrase);
                else
                        old_passphrase =
                            read_passphrase("Enter old passphrase: ",
                            RP_ALLOW_STDIN);
                r = sshkey_load_private(identity_file, old_passphrase,
                    &private, &comment);
                freezero(old_passphrase, strlen(old_passphrase));
                if (r != 0)
                        goto badkey;
        } else if (r != 0) {
 badkey:
                fatal_r(r, "Failed to load key %s", identity_file);
        }
        if (comment)
                mprintf("Key has comment '%s'\n", comment);

        /* Ask the new passphrase (twice). */
        if (identity_new_passphrase) {
                passphrase1 = xstrdup(identity_new_passphrase);
                passphrase2 = NULL;
        } else {
                passphrase1 =
                        read_passphrase("Enter new passphrase (empty for no "
                            "passphrase): ", RP_ALLOW_STDIN);
                passphrase2 = read_passphrase("Enter same passphrase again: ",
                    RP_ALLOW_STDIN);

                /* Verify that they are the same. */
                if (strcmp(passphrase1, passphrase2) != 0) {
                        explicit_bzero(passphrase1, strlen(passphrase1));
                        explicit_bzero(passphrase2, strlen(passphrase2));
                        free(passphrase1);
                        free(passphrase2);
                        printf("Pass phrases do not match.  Try again.\n");
                        exit(1);
                }
                /* Destroy the other copy. */
                freezero(passphrase2, strlen(passphrase2));
        }

        /* Save the file using the new passphrase. */
        if ((r = sshkey_save_private(private, identity_file, passphrase1,
            comment, private_key_format, openssh_format_cipher, rounds)) != 0) {
                error_r(r, "Saving key \"%s\" failed", identity_file);
                freezero(passphrase1, strlen(passphrase1));
                sshkey_free(private);
                free(comment);
                exit(1);
        }
        /* Destroy the passphrase and the copy of the key in memory. */
        freezero(passphrase1, strlen(passphrase1));
        sshkey_free(private);            /* Destroys contents */
        free(comment);

        printf("Your identification has been saved with the new passphrase.\n");
        exit(0);
}

/*
 * Print the SSHFP RR.
 */
static int
do_print_resource_record(struct passwd *pw, char *fname, char *hname,
    int print_generic, char * const *opts, size_t nopts)
{
        struct sshkey *public;
        char *comment = NULL;
        struct stat st;
        int r, hash = -1;
        size_t i;

        for (i = 0; i < nopts; i++) {
                if (strncasecmp(opts[i], "hashalg=", 8) == 0) {
                        if ((hash = ssh_digest_alg_by_name(opts[i] + 8)) == -1)
                                fatal("Unsupported hash algorithm");
                } else {
                        error("Invalid option \"%s\"", opts[i]);
                        return SSH_ERR_INVALID_ARGUMENT;
                }
        }
        if (fname == NULL)
                fatal_f("no filename");
        if (stat(fname, &st) == -1) {
                if (errno == ENOENT)
                        return 0;
                fatal("%s: %s", fname, strerror(errno));
        }
        if ((r = sshkey_load_public(fname, &public, &comment)) != 0)
                fatal_r(r, "Failed to read v2 public key from \"%s\"", fname);
        export_dns_rr(hname, public, stdout, print_generic, hash);
        sshkey_free(public);
        free(comment);
        return 1;
}

/*
 * Change the comment of a private key file.
 */
static void
do_change_comment(struct passwd *pw, const char *identity_comment)
{
        char new_comment[1024], *comment, *passphrase;
        struct sshkey *private;
        struct sshkey *public;
        struct stat st;
        int r;

        if (!have_identity)
                ask_filename(pw, "Enter file in which the key is");
        if (stat(identity_file, &st) == -1)
                fatal("%s: %s", identity_file, strerror(errno));
        if ((r = sshkey_load_private(identity_file, "",
            &private, &comment)) == 0)
                passphrase = xstrdup("");
        else if (r != SSH_ERR_KEY_WRONG_PASSPHRASE)
                fatal_r(r, "Cannot load private key \"%s\"", identity_file);
        else {
                if (identity_passphrase)
                        passphrase = xstrdup(identity_passphrase);
                else if (identity_new_passphrase)
                        passphrase = xstrdup(identity_new_passphrase);
                else
                        passphrase = read_passphrase("Enter passphrase: ",
                            RP_ALLOW_STDIN);
                /* Try to load using the passphrase. */
                if ((r = sshkey_load_private(identity_file, passphrase,
                    &private, &comment)) != 0) {
                        freezero(passphrase, strlen(passphrase));
                        fatal_r(r, "Cannot load private key \"%s\"",
                            identity_file);
                }
        }

        if (private->type != KEY_ED25519 && private->type != KEY_XMSS &&
            private_key_format != SSHKEY_PRIVATE_OPENSSH) {
                error("Comments are only supported for keys stored in "
                    "the new format (-o).");
                explicit_bzero(passphrase, strlen(passphrase));
                sshkey_free(private);
                exit(1);
        }
        if (comment)
                printf("Old comment: %s\n", comment);
        else
                printf("No existing comment\n");

        if (identity_comment) {
                strlcpy(new_comment, identity_comment, sizeof(new_comment));
        } else {
                printf("New comment: ");
                fflush(stdout);
                if (!fgets(new_comment, sizeof(new_comment), stdin)) {
                        explicit_bzero(passphrase, strlen(passphrase));
                        sshkey_free(private);
                        exit(1);
                }
                new_comment[strcspn(new_comment, "\n")] = '\0';
        }
        if (comment != NULL && strcmp(comment, new_comment) == 0) {
                printf("No change to comment\n");
                free(passphrase);
                sshkey_free(private);
                free(comment);
                exit(0);
        }

        /* Save the file using the new passphrase. */
        if ((r = sshkey_save_private(private, identity_file, passphrase,
            new_comment, private_key_format, openssh_format_cipher,
            rounds)) != 0) {
                error_r(r, "Saving key \"%s\" failed", identity_file);
                freezero(passphrase, strlen(passphrase));
                sshkey_free(private);
                free(comment);
                exit(1);
        }
        freezero(passphrase, strlen(passphrase));
        if ((r = sshkey_from_private(private, &public)) != 0)
                fatal_fr(r, "sshkey_from_private");
        sshkey_free(private);

        strlcat(identity_file, ".pub", sizeof(identity_file));
        if ((r = sshkey_save_public(public, identity_file, new_comment)) != 0)
                fatal_r(r, "Unable to save public key to %s", identity_file);
        sshkey_free(public);
        free(comment);

        if (strlen(new_comment) > 0)
                printf("Comment '%s' applied\n", new_comment);
        else
                printf("Comment removed\n");

        exit(0);
}

static void
cert_ext_add(const char *key, const char *value, int iscrit)
{
        cert_ext = xreallocarray(cert_ext, ncert_ext + 1, sizeof(*cert_ext));
        cert_ext[ncert_ext].key = xstrdup(key);
        cert_ext[ncert_ext].val = value == NULL ? NULL : xstrdup(value);
        cert_ext[ncert_ext].crit = iscrit;
        ncert_ext++;
}

/* qsort(3) comparison function for certificate extensions */
static int
cert_ext_cmp(const void *_a, const void *_b)
{
        const struct cert_ext *a = (const struct cert_ext *)_a;
        const struct cert_ext *b = (const struct cert_ext *)_b;
        int r;

        if (a->crit != b->crit)
                return (a->crit < b->crit) ? -1 : 1;
        if ((r = strcmp(a->key, b->key)) != 0)
                return r;
        if ((a->val == NULL) != (b->val == NULL))
                return (a->val == NULL) ? -1 : 1;
        if (a->val != NULL && (r = strcmp(a->val, b->val)) != 0)
                return r;
        return 0;
}

#define OPTIONS_CRITICAL        1
#define OPTIONS_EXTENSIONS      2
static void
prepare_options_buf(struct sshbuf *c, int which)
{
        struct sshbuf *b;
        size_t i;
        int r;
        const struct cert_ext *ext;

        if ((b = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        sshbuf_reset(c);
        for (i = 0; i < ncert_ext; i++) {
                ext = &cert_ext[i];
                if ((ext->crit && (which & OPTIONS_EXTENSIONS)) ||
                    (!ext->crit && (which & OPTIONS_CRITICAL)))
                        continue;
                if (ext->val == NULL) {
                        /* flag option */
                        debug3_f("%s", ext->key);
                        if ((r = sshbuf_put_cstring(c, ext->key)) != 0 ||
                            (r = sshbuf_put_string(c, NULL, 0)) != 0)
                                fatal_fr(r, "prepare flag");
                } else {
                        /* key/value option */
                        debug3_f("%s=%s", ext->key, ext->val);
                        sshbuf_reset(b);
                        if ((r = sshbuf_put_cstring(c, ext->key)) != 0 ||
                            (r = sshbuf_put_cstring(b, ext->val)) != 0 ||
                            (r = sshbuf_put_stringb(c, b)) != 0)
                                fatal_fr(r, "prepare k/v");
                }
        }
        sshbuf_free(b);
}

static void
finalise_cert_exts(void)
{
        /* critical options */
        if (certflags_command != NULL)
                cert_ext_add("force-command", certflags_command, 1);
        if (certflags_src_addr != NULL)
                cert_ext_add("source-address", certflags_src_addr, 1);
        if ((certflags_flags & CERTOPT_REQUIRE_VERIFY) != 0)
                cert_ext_add("verify-required", NULL, 1);
        /* extensions */
        if ((certflags_flags & CERTOPT_X_FWD) != 0)
                cert_ext_add("permit-X11-forwarding", NULL, 0);
        if ((certflags_flags & CERTOPT_AGENT_FWD) != 0)
                cert_ext_add("permit-agent-forwarding", NULL, 0);
        if ((certflags_flags & CERTOPT_PORT_FWD) != 0)
                cert_ext_add("permit-port-forwarding", NULL, 0);
        if ((certflags_flags & CERTOPT_PTY) != 0)
                cert_ext_add("permit-pty", NULL, 0);
        if ((certflags_flags & CERTOPT_USER_RC) != 0)
                cert_ext_add("permit-user-rc", NULL, 0);
        if ((certflags_flags & CERTOPT_NO_REQUIRE_USER_PRESENCE) != 0)
                cert_ext_add("no-touch-required", NULL, 0);
        /* order lexically by key */
        if (ncert_ext > 0)
                qsort(cert_ext, ncert_ext, sizeof(*cert_ext), cert_ext_cmp);
}

static struct sshkey *
load_pkcs11_key(char *path)
{
#ifdef ENABLE_PKCS11
        struct sshkey **keys = NULL, *public, *private = NULL;
        int r, i, nkeys;

        if ((r = sshkey_load_public(path, &public, NULL)) != 0)
                fatal_r(r, "Couldn't load CA public key \"%s\"", path);

        nkeys = pkcs11_add_provider(pkcs11provider, identity_passphrase,
            &keys, NULL);
        debug3_f("%d keys", nkeys);
        if (nkeys <= 0)
                fatal("cannot read public key from pkcs11");
        for (i = 0; i < nkeys; i++) {
                if (sshkey_equal_public(public, keys[i])) {
                        private = keys[i];
                        continue;
                }
                sshkey_free(keys[i]);
        }
        free(keys);
        sshkey_free(public);
        return private;
#else
        fatal("no pkcs11 support");
#endif /* ENABLE_PKCS11 */
}

/* Signer for sshkey_certify_custom that uses the agent */
static int
agent_signer(struct sshkey *key, u_char **sigp, size_t *lenp,
    const u_char *data, size_t datalen,
    const char *alg, const char *provider, const char *pin,
    u_int compat, void *ctx)
{
        int *agent_fdp = (int *)ctx;

        return ssh_agent_sign(*agent_fdp, key, sigp, lenp,
            data, datalen, alg, compat);
}

static void
do_ca_sign(struct passwd *pw, const char *ca_key_path, int prefer_agent,
    unsigned long long cert_serial, int cert_serial_autoinc,
    int argc, char **argv)
{
        int r, i, found, agent_fd = -1;
        u_int n;
        struct sshkey *ca, *public;
        char valid[64], *otmp, *tmp, *cp, *out, *comment;
        char *ca_fp = NULL, **plist = NULL, *pin = NULL;
        struct ssh_identitylist *agent_ids;
        size_t j;
        struct notifier_ctx *notifier = NULL;

#ifdef ENABLE_PKCS11
        pkcs11_init(1);
#endif
        tmp = tilde_expand_filename(ca_key_path, pw->pw_uid);
        if (pkcs11provider != NULL) {
                /* If a PKCS#11 token was specified then try to use it */
                if ((ca = load_pkcs11_key(tmp)) == NULL)
                        fatal("No PKCS#11 key matching %s found", ca_key_path);
        } else if (prefer_agent) {
                /*
                 * Agent signature requested. Try to use agent after making
                 * sure the public key specified is actually present in the
                 * agent.
                 */
                if ((r = sshkey_load_public(tmp, &ca, NULL)) != 0)
                        fatal_r(r, "Cannot load CA public key %s", tmp);
                if ((r = ssh_get_authentication_socket(&agent_fd)) != 0)
                        fatal_r(r, "Cannot use public key for CA signature");
                if ((r = ssh_fetch_identitylist(agent_fd, &agent_ids)) != 0)
                        fatal_r(r, "Retrieve agent key list");
                found = 0;
                for (j = 0; j < agent_ids->nkeys; j++) {
                        if (sshkey_equal(ca, agent_ids->keys[j])) {
                                found = 1;
                                break;
                        }
                }
                if (!found)
                        fatal("CA key %s not found in agent", tmp);
                ssh_free_identitylist(agent_ids);
                ca->flags |= SSHKEY_FLAG_EXT;
        } else {
                /* CA key is assumed to be a private key on the filesystem */
                ca = load_identity(tmp, NULL);
                if (sshkey_is_sk(ca) &&
                    (ca->sk_flags & SSH_SK_USER_VERIFICATION_REQD)) {
                        if ((pin = read_passphrase("Enter PIN for CA key: ",
                            RP_ALLOW_STDIN)) == NULL)
                                fatal_f("couldn't read PIN");
                }
        }
        free(tmp);

        if (key_type_name != NULL) {
                if (sshkey_type_from_shortname(key_type_name) != ca->type) {
                        fatal("CA key type %s doesn't match specified %s",
                            sshkey_ssh_name(ca), key_type_name);
                }
        } else if (ca->type == KEY_RSA) {
                /* Default to a good signature algorithm */
                key_type_name = "rsa-sha2-512";
        }
        ca_fp = sshkey_fingerprint(ca, fingerprint_hash, SSH_FP_DEFAULT);

        finalise_cert_exts();
        for (i = 0; i < argc; i++) {
                /* Split list of principals */
                n = 0;
                if (cert_principals != NULL) {
                        otmp = tmp = xstrdup(cert_principals);
                        plist = NULL;
                        for (; (cp = strsep(&tmp, ",")) != NULL; n++) {
                                plist = xreallocarray(plist, n + 1, sizeof(*plist));
                                if (*(plist[n] = xstrdup(cp)) == '\0')
                                        fatal("Empty principal name");
                        }
                        free(otmp);
                }
                if (n > SSHKEY_CERT_MAX_PRINCIPALS)
                        fatal("Too many certificate principals specified");

                tmp = tilde_expand_filename(argv[i], pw->pw_uid);
                if ((r = sshkey_load_public(tmp, &public, &comment)) != 0)
                        fatal_r(r, "load pubkey \"%s\"", tmp);
                if (sshkey_is_cert(public))
                        fatal_f("key \"%s\" type %s cannot be certified",
                            tmp, sshkey_type(public));

                /* Prepare certificate to sign */
                if ((r = sshkey_to_certified(public)) != 0)
                        fatal_r(r, "Could not upgrade key %s to certificate", tmp);
                public->cert->type = cert_key_type;
                public->cert->serial = (u_int64_t)cert_serial;
                public->cert->key_id = xstrdup(cert_key_id);
                public->cert->nprincipals = n;
                public->cert->principals = plist;
                public->cert->valid_after = cert_valid_from;
                public->cert->valid_before = cert_valid_to;
                prepare_options_buf(public->cert->critical, OPTIONS_CRITICAL);
                prepare_options_buf(public->cert->extensions,
                    OPTIONS_EXTENSIONS);
                if ((r = sshkey_from_private(ca,
                    &public->cert->signature_key)) != 0)
                        fatal_r(r, "sshkey_from_private (ca key)");

                if (agent_fd != -1 && (ca->flags & SSHKEY_FLAG_EXT) != 0) {
                        if ((r = sshkey_certify_custom(public, ca,
                            key_type_name, sk_provider, NULL, agent_signer,
                            &agent_fd)) != 0)
                                fatal_r(r, "Couldn't certify %s via agent", tmp);
                } else {
                        if (sshkey_is_sk(ca) &&
                            (ca->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
                                notifier = notify_start(0,
                                    "Confirm user presence for key %s %s",
                                    sshkey_type(ca), ca_fp);
                        }
                        r = sshkey_certify(public, ca, key_type_name,
                            sk_provider, pin);
                        notify_complete(notifier, "User presence confirmed");
                        if (r != 0)
                                fatal_r(r, "Couldn't certify key %s", tmp);
                }

                if ((cp = strrchr(tmp, '.')) != NULL && strcmp(cp, ".pub") == 0)
                        *cp = '\0';
                xasprintf(&out, "%s-cert.pub", tmp);
                free(tmp);

                if ((r = sshkey_save_public(public, out, comment)) != 0) {
                        fatal_r(r, "Unable to save public key to %s",
                            identity_file);
                }

                if (!quiet) {
                        sshkey_format_cert_validity(public->cert,
                            valid, sizeof(valid));
                        logit("Signed %s key %s: id \"%s\" serial %llu%s%s "
                            "valid %s", sshkey_cert_type(public),
                            out, public->cert->key_id,
                            (unsigned long long)public->cert->serial,
                            cert_principals != NULL ? " for " : "",
                            cert_principals != NULL ? cert_principals : "",
                            valid);
                }

                sshkey_free(public);
                free(out);
                if (cert_serial_autoinc)
                        cert_serial++;
        }
        if (pin != NULL)
                freezero(pin, strlen(pin));
        free(ca_fp);
#ifdef ENABLE_PKCS11
        pkcs11_terminate();
#endif
        exit(0);
}

static u_int64_t
parse_relative_time(const char *s, time_t now)
{
        int64_t mul, secs;

        mul = *s == '-' ? -1 : 1;

        if ((secs = convtime(s + 1)) == -1)
                fatal("Invalid relative certificate time %s", s);
        if (mul == -1 && secs > now)
                fatal("Certificate time %s cannot be represented", s);
        return now + (u_int64_t)(secs * mul);
}

static void
parse_hex_u64(const char *s, uint64_t *up)
{
        char *ep;
        unsigned long long ull;

        errno = 0;
        ull = strtoull(s, &ep, 16);
        if (*s == '\0' || *ep != '\0')
                fatal("Invalid certificate time: not a number");
        if (errno == ERANGE && ull == ULONG_MAX)
                fatal_fr(SSH_ERR_SYSTEM_ERROR, "Invalid certificate time");
        *up = (uint64_t)ull;
}

static void
parse_cert_times(char *timespec)
{
        char *from, *to;
        time_t now = time(NULL);
        int64_t secs;

        /* +timespec relative to now */
        if (*timespec == '+' && strchr(timespec, ':') == NULL) {
                if ((secs = convtime(timespec + 1)) == -1)
                        fatal("Invalid relative certificate life %s", timespec);
                cert_valid_to = now + secs;
                /*
                 * Backdate certificate one minute to avoid problems on hosts
                 * with poorly-synchronised clocks.
                 */
                cert_valid_from = ((now - 59)/ 60) * 60;
                return;
        }

        /*
         * from:to, where
         * from := [+-]timespec | YYYYMMDD | YYYYMMDDHHMMSS | 0x... | "always"
         *   to := [+-]timespec | YYYYMMDD | YYYYMMDDHHMMSS | 0x... | "forever"
         */
        from = xstrdup(timespec);
        to = strchr(from, ':');
        if (to == NULL || from == to || *(to + 1) == '\0')
                fatal("Invalid certificate life specification %s", timespec);
        *to++ = '\0';

        if (*from == '-' || *from == '+')
                cert_valid_from = parse_relative_time(from, now);
        else if (strcmp(from, "always") == 0)
                cert_valid_from = 0;
        else if (strncmp(from, "0x", 2) == 0)
                parse_hex_u64(from, &cert_valid_from);
        else if (parse_absolute_time(from, &cert_valid_from) != 0)
                fatal("Invalid from time \"%s\"", from);

        if (*to == '-' || *to == '+')
                cert_valid_to = parse_relative_time(to, now);
        else if (strcmp(to, "forever") == 0)
                cert_valid_to = ~(u_int64_t)0;
        else if (strncmp(to, "0x", 2) == 0)
                parse_hex_u64(to, &cert_valid_to);
        else if (parse_absolute_time(to, &cert_valid_to) != 0)
                fatal("Invalid to time \"%s\"", to);

        if (cert_valid_to <= cert_valid_from)
                fatal("Empty certificate validity interval");
        free(from);
}

static void
add_cert_option(char *opt)
{
        char *val, *cp;
        int iscrit = 0;

        if (strcasecmp(opt, "clear") == 0)
                certflags_flags = 0;
        else if (strcasecmp(opt, "no-x11-forwarding") == 0)
                certflags_flags &= ~CERTOPT_X_FWD;
        else if (strcasecmp(opt, "permit-x11-forwarding") == 0)
                certflags_flags |= CERTOPT_X_FWD;
        else if (strcasecmp(opt, "no-agent-forwarding") == 0)
                certflags_flags &= ~CERTOPT_AGENT_FWD;
        else if (strcasecmp(opt, "permit-agent-forwarding") == 0)
                certflags_flags |= CERTOPT_AGENT_FWD;
        else if (strcasecmp(opt, "no-port-forwarding") == 0)
                certflags_flags &= ~CERTOPT_PORT_FWD;
        else if (strcasecmp(opt, "permit-port-forwarding") == 0)
                certflags_flags |= CERTOPT_PORT_FWD;
        else if (strcasecmp(opt, "no-pty") == 0)
                certflags_flags &= ~CERTOPT_PTY;
        else if (strcasecmp(opt, "permit-pty") == 0)
                certflags_flags |= CERTOPT_PTY;
        else if (strcasecmp(opt, "no-user-rc") == 0)
                certflags_flags &= ~CERTOPT_USER_RC;
        else if (strcasecmp(opt, "permit-user-rc") == 0)
                certflags_flags |= CERTOPT_USER_RC;
        else if (strcasecmp(opt, "touch-required") == 0)
                certflags_flags &= ~CERTOPT_NO_REQUIRE_USER_PRESENCE;
        else if (strcasecmp(opt, "no-touch-required") == 0)
                certflags_flags |= CERTOPT_NO_REQUIRE_USER_PRESENCE;
        else if (strcasecmp(opt, "no-verify-required") == 0)
                certflags_flags &= ~CERTOPT_REQUIRE_VERIFY;
        else if (strcasecmp(opt, "verify-required") == 0)
                certflags_flags |= CERTOPT_REQUIRE_VERIFY;
        else if (strncasecmp(opt, "force-command=", 14) == 0) {
                val = opt + 14;
                if (*val == '\0')
                        fatal("Empty force-command option");
                if (certflags_command != NULL)
                        fatal("force-command already specified");
                certflags_command = xstrdup(val);
        } else if (strncasecmp(opt, "source-address=", 15) == 0) {
                val = opt + 15;
                if (*val == '\0')
                        fatal("Empty source-address option");
                if (certflags_src_addr != NULL)
                        fatal("source-address already specified");
                if (addr_match_cidr_list(NULL, val) != 0)
                        fatal("Invalid source-address list");
                certflags_src_addr = xstrdup(val);
        } else if (strncasecmp(opt, "extension:", 10) == 0 ||
                    (iscrit = (strncasecmp(opt, "critical:", 9) == 0))) {
                val = xstrdup(strchr(opt, ':') + 1);
                if ((cp = strchr(val, '=')) != NULL)
                        *cp++ = '\0';
                cert_ext_add(val, cp, iscrit);
                free(val);
        } else
                fatal("Unsupported certificate option \"%s\"", opt);
}

static void
show_options(struct sshbuf *optbuf, int in_critical)
{
        char *name, *arg, *hex;
        struct sshbuf *options, *option = NULL;
        int r;

        if ((options = sshbuf_fromb(optbuf)) == NULL)
                fatal_f("sshbuf_fromb failed");
        while (sshbuf_len(options) != 0) {
                sshbuf_free(option);
                option = NULL;
                if ((r = sshbuf_get_cstring(options, &name, NULL)) != 0 ||
                    (r = sshbuf_froms(options, &option)) != 0)
                        fatal_fr(r, "parse option");
                printf("                %s", name);
                if (!in_critical &&
                    (strcmp(name, "permit-X11-forwarding") == 0 ||
                    strcmp(name, "permit-agent-forwarding") == 0 ||
                    strcmp(name, "permit-port-forwarding") == 0 ||
                    strcmp(name, "permit-pty") == 0 ||
                    strcmp(name, "permit-user-rc") == 0 ||
                    strcmp(name, "no-touch-required") == 0)) {
                        printf("\n");
                } else if (in_critical &&
                    (strcmp(name, "force-command") == 0 ||
                    strcmp(name, "source-address") == 0)) {
                        if ((r = sshbuf_get_cstring(option, &arg, NULL)) != 0)
                                fatal_fr(r, "parse critical");
                        printf(" %s\n", arg);
                        free(arg);
                } else if (in_critical &&
                    strcmp(name, "verify-required") == 0) {
                        printf("\n");
                } else if (sshbuf_len(option) > 0) {
                        hex = sshbuf_dtob16(option);
                        printf(" UNKNOWN OPTION: %s (len %zu)\n",
                            hex, sshbuf_len(option));
                        sshbuf_reset(option);
                        free(hex);
                } else
                        printf(" UNKNOWN FLAG OPTION\n");
                free(name);
                if (sshbuf_len(option) != 0)
                        fatal("Option corrupt: extra data at end");
        }
        sshbuf_free(option);
        sshbuf_free(options);
}

static void
print_cert(struct sshkey *key)
{
        char valid[64], *key_fp, *ca_fp;
        u_int i;

        key_fp = sshkey_fingerprint(key, fingerprint_hash, SSH_FP_DEFAULT);
        ca_fp = sshkey_fingerprint(key->cert->signature_key,
            fingerprint_hash, SSH_FP_DEFAULT);
        if (key_fp == NULL || ca_fp == NULL)
                fatal_f("sshkey_fingerprint fail");
        sshkey_format_cert_validity(key->cert, valid, sizeof(valid));

        printf("        Type: %s %s certificate\n", sshkey_ssh_name(key),
            sshkey_cert_type(key));
        printf("        Public key: %s %s\n", sshkey_type(key), key_fp);
        printf("        Signing CA: %s %s (using %s)\n",
            sshkey_type(key->cert->signature_key), ca_fp,
            key->cert->signature_type);
        printf("        Key ID: \"%s\"\n", key->cert->key_id);
        printf("        Serial: %llu\n", (unsigned long long)key->cert->serial);
        printf("        Valid: %s\n", valid);
        printf("        Principals: ");
        if (key->cert->nprincipals == 0)
                printf("(none)\n");
        else {
                for (i = 0; i < key->cert->nprincipals; i++)
                        printf("\n                %s",
                            key->cert->principals[i]);
                printf("\n");
        }
        printf("        Critical Options: ");
        if (sshbuf_len(key->cert->critical) == 0)
                printf("(none)\n");
        else {
                printf("\n");
                show_options(key->cert->critical, 1);
        }
        printf("        Extensions: ");
        if (sshbuf_len(key->cert->extensions) == 0)
                printf("(none)\n");
        else {
                printf("\n");
                show_options(key->cert->extensions, 0);
        }
}

static void
do_show_cert(struct passwd *pw)
{
        struct sshkey *key = NULL;
        struct stat st;
        int r, is_stdin = 0, ok = 0;
        FILE *f;
        char *cp, *line = NULL;
        const char *path;
        size_t linesize = 0;
        u_long lnum = 0;

        if (!have_identity)
                ask_filename(pw, "Enter file in which the key is");
        if (strcmp(identity_file, "-") != 0 && stat(identity_file, &st) == -1)
                fatal("%s: %s: %s", __progname, identity_file, strerror(errno));

        path = identity_file;
        if (strcmp(path, "-") == 0) {
                f = stdin;
                path = "(stdin)";
                is_stdin = 1;
        } else if ((f = fopen(identity_file, "r")) == NULL)
                fatal("fopen %s: %s", identity_file, strerror(errno));

        while (getline(&line, &linesize, f) != -1) {
                lnum++;
                sshkey_free(key);
                key = NULL;
                /* Trim leading space and comments */
                cp = line + strspn(line, " \t");
                if (*cp == '#' || *cp == '\0')
                        continue;
                if ((key = sshkey_new(KEY_UNSPEC)) == NULL)
                        fatal("sshkey_new");
                if ((r = sshkey_read(key, &cp)) != 0) {
                        error_r(r, "%s:%lu: invalid key", path, lnum);
                        continue;
                }
                if (!sshkey_is_cert(key)) {
                        error("%s:%lu is not a certificate", path, lnum);
                        continue;
                }
                ok = 1;
                if (!is_stdin && lnum == 1)
                        printf("%s:\n", path);
                else
                        printf("%s:%lu:\n", path, lnum);
                print_cert(key);
        }
        free(line);
        sshkey_free(key);
        fclose(f);
        exit(ok ? 0 : 1);
}

static void
load_krl(const char *path, struct ssh_krl **krlp)
{
        struct sshbuf *krlbuf;
        int r;

        if ((r = sshbuf_load_file(path, &krlbuf)) != 0)
                fatal_r(r, "Unable to load KRL %s", path);
        /* XXX check sigs */
        if ((r = ssh_krl_from_blob(krlbuf, krlp)) != 0 ||
            *krlp == NULL)
                fatal_r(r, "Invalid KRL file %s", path);
        sshbuf_free(krlbuf);
}

static void
hash_to_blob(const char *cp, u_char **blobp, size_t *lenp,
    const char *file, u_long lnum)
{
        char *tmp;
        size_t tlen;
        struct sshbuf *b;
        int r;

        if (strncmp(cp, "SHA256:", 7) != 0)
                fatal("%s:%lu: unsupported hash algorithm", file, lnum);
        cp += 7;

        /*
         * OpenSSH base64 hashes omit trailing '='
         * characters; put them back for decode.
         */
        if ((tlen = strlen(cp)) >= SIZE_MAX - 5)
                fatal_f("hash too long: %zu bytes", tlen);
        tmp = xmalloc(tlen + 4 + 1);
        strlcpy(tmp, cp, tlen + 1);
        while ((tlen % 4) != 0) {
                tmp[tlen++] = '=';
                tmp[tlen] = '\0';
        }
        if ((b = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_b64tod(b, tmp)) != 0)
                fatal_r(r, "%s:%lu: decode hash failed", file, lnum);
        free(tmp);
        *lenp = sshbuf_len(b);
        *blobp = xmalloc(*lenp);
        memcpy(*blobp, sshbuf_ptr(b), *lenp);
        sshbuf_free(b);
}

static void
update_krl_from_file(struct passwd *pw, const char *file, int wild_ca,
    const struct sshkey *ca, struct ssh_krl *krl)
{
        struct sshkey *key = NULL;
        u_long lnum = 0;
        char *path, *cp, *ep, *line = NULL;
        u_char *blob = NULL;
        size_t blen = 0, linesize = 0;
        unsigned long long serial, serial2;
        int i, was_explicit_key, was_sha1, was_sha256, was_hash, r;
        FILE *krl_spec;

        path = tilde_expand_filename(file, pw->pw_uid);
        if (strcmp(path, "-") == 0) {
                krl_spec = stdin;
                free(path);
                path = xstrdup("(standard input)");
        } else if ((krl_spec = fopen(path, "r")) == NULL)
                fatal("fopen %s: %s", path, strerror(errno));

        if (!quiet)
                printf("Revoking from %s\n", path);
        while (getline(&line, &linesize, krl_spec) != -1) {
                if (linesize >= INT_MAX) {
                        fatal_f("%s contains unparsable line, len=%zu",
                            path, linesize);
                }
                lnum++;
                was_explicit_key = was_sha1 = was_sha256 = was_hash = 0;
                cp = line + strspn(line, " \t");
                /* Trim trailing space, comments and strip \n */
                for (i = 0, r = -1; cp[i] != '\0'; i++) {
                        if (cp[i] == '#' || cp[i] == '\n') {
                                cp[i] = '\0';
                                break;
                        }
                        if (cp[i] == ' ' || cp[i] == '\t') {
                                /* Remember the start of a span of whitespace */
                                if (r == -1)
                                        r = i;
                        } else
                                r = -1;
                }
                if (r != -1)
                        cp[r] = '\0';
                if (*cp == '\0')
                        continue;
                if (strncasecmp(cp, "serial:", 7) == 0) {
                        if (ca == NULL && !wild_ca) {
                                fatal("revoking certificates by serial number "
                                    "requires specification of a CA key");
                        }
                        cp += 7;
                        cp = cp + strspn(cp, " \t");
                        errno = 0;
                        serial = strtoull(cp, &ep, 0);
                        if (*cp == '\0' || (*ep != '\0' && *ep != '-'))
                                fatal("%s:%lu: invalid serial \"%s\"",
                                    path, lnum, cp);
                        if (errno == ERANGE && serial == ULLONG_MAX)
                                fatal("%s:%lu: serial out of range",
                                    path, lnum);
                        serial2 = serial;
                        if (*ep == '-') {
                                cp = ep + 1;
                                errno = 0;
                                serial2 = strtoull(cp, &ep, 0);
                                if (*cp == '\0' || *ep != '\0')
                                        fatal("%s:%lu: invalid serial \"%s\"",
                                            path, lnum, cp);
                                if (errno == ERANGE && serial2 == ULLONG_MAX)
                                        fatal("%s:%lu: serial out of range",
                                            path, lnum);
                                if (serial2 <= serial)
                                        fatal("%s:%lu: invalid serial range "
                                            "%llu:%llu", path, lnum,
                                            (unsigned long long)serial,
                                            (unsigned long long)serial2);
                        }
                        if (ssh_krl_revoke_cert_by_serial_range(krl,
                            ca, serial, serial2) != 0) {
                                fatal_f("revoke serial failed");
                        }
                } else if (strncasecmp(cp, "id:", 3) == 0) {
                        if (ca == NULL && !wild_ca) {
                                fatal("revoking certificates by key ID "
                                    "requires specification of a CA key");
                        }
                        cp += 3;
                        cp = cp + strspn(cp, " \t");
                        if (ssh_krl_revoke_cert_by_key_id(krl, ca, cp) != 0)
                                fatal_f("revoke key ID failed");
                } else if (strncasecmp(cp, "hash:", 5) == 0) {
                        cp += 5;
                        cp = cp + strspn(cp, " \t");
                        hash_to_blob(cp, &blob, &blen, file, lnum);
                        r = ssh_krl_revoke_key_sha256(krl, blob, blen);
                        if (r != 0)
                                fatal_fr(r, "revoke key failed");
                } else {
                        if (strncasecmp(cp, "key:", 4) == 0) {
                                cp += 4;
                                cp = cp + strspn(cp, " \t");
                                was_explicit_key = 1;
                        } else if (strncasecmp(cp, "sha1:", 5) == 0) {
                                cp += 5;
                                cp = cp + strspn(cp, " \t");
                                was_sha1 = 1;
                        } else if (strncasecmp(cp, "sha256:", 7) == 0) {
                                cp += 7;
                                cp = cp + strspn(cp, " \t");
                                was_sha256 = 1;
                                /*
                                 * Just try to process the line as a key.
                                 * Parsing will fail if it isn't.
                                 */
                        }
                        if ((key = sshkey_new(KEY_UNSPEC)) == NULL)
                                fatal("sshkey_new");
                        if ((r = sshkey_read(key, &cp)) != 0)
                                fatal_r(r, "%s:%lu: invalid key", path, lnum);
                        if (was_explicit_key)
                                r = ssh_krl_revoke_key_explicit(krl, key);
                        else if (was_sha1) {
                                if (sshkey_fingerprint_raw(key,
                                    SSH_DIGEST_SHA1, &blob, &blen) != 0) {
                                        fatal("%s:%lu: fingerprint failed",
                                            file, lnum);
                                }
                                r = ssh_krl_revoke_key_sha1(krl, blob, blen);
                        } else if (was_sha256) {
                                if (sshkey_fingerprint_raw(key,
                                    SSH_DIGEST_SHA256, &blob, &blen) != 0) {
                                        fatal("%s:%lu: fingerprint failed",
                                            file, lnum);
                                }
                                r = ssh_krl_revoke_key_sha256(krl, blob, blen);
                        } else
                                r = ssh_krl_revoke_key(krl, key);
                        if (r != 0)
                                fatal_fr(r, "revoke key failed");
                        freezero(blob, blen);
                        blob = NULL;
                        blen = 0;
                        sshkey_free(key);
                }
        }
        if (strcmp(path, "-") != 0)
                fclose(krl_spec);
        free(line);
        free(path);
}

static void
do_gen_krl(struct passwd *pw, int updating, const char *ca_key_path,
    unsigned long long krl_version, const char *krl_comment,
    int argc, char **argv)
{
        struct ssh_krl *krl;
        struct stat sb;
        struct sshkey *ca = NULL;
        int i, r, wild_ca = 0;
        char *tmp;
        struct sshbuf *kbuf;

        if (*identity_file == '\0')
                fatal("KRL generation requires an output file");
        if (stat(identity_file, &sb) == -1) {
                if (errno != ENOENT)
                        fatal("Cannot access KRL \"%s\": %s",
                            identity_file, strerror(errno));
                if (updating)
                        fatal("KRL \"%s\" does not exist", identity_file);
        }
        if (ca_key_path != NULL) {
                if (strcasecmp(ca_key_path, "none") == 0)
                        wild_ca = 1;
                else {
                        tmp = tilde_expand_filename(ca_key_path, pw->pw_uid);
                        if ((r = sshkey_load_public(tmp, &ca, NULL)) != 0)
                                fatal_r(r, "Cannot load CA public key %s", tmp);
                        free(tmp);
                }
        }

        if (updating)
                load_krl(identity_file, &krl);
        else if ((krl = ssh_krl_init()) == NULL)
                fatal("couldn't create KRL");

        if (krl_version != 0)
                ssh_krl_set_version(krl, krl_version);
        if (krl_comment != NULL)
                ssh_krl_set_comment(krl, krl_comment);

        for (i = 0; i < argc; i++)
                update_krl_from_file(pw, argv[i], wild_ca, ca, krl);

        if ((kbuf = sshbuf_new()) == NULL)
                fatal("sshbuf_new failed");
        if (ssh_krl_to_blob(krl, kbuf) != 0)
                fatal("Couldn't generate KRL");
        if ((r = sshbuf_write_file(identity_file, kbuf)) != 0)
                fatal("write %s: %s", identity_file, strerror(errno));
        sshbuf_free(kbuf);
        ssh_krl_free(krl);
        sshkey_free(ca);
}

static void
do_check_krl(struct passwd *pw, int print_krl, int argc, char **argv)
{
        int i, r, ret = 0;
        char *comment;
        struct ssh_krl *krl;
        struct sshkey *k;

        if (*identity_file == '\0')
                fatal("KRL checking requires an input file");
        load_krl(identity_file, &krl);
        if (print_krl)
                krl_dump(krl, stdout);
        for (i = 0; i < argc; i++) {
                if ((r = sshkey_load_public(argv[i], &k, &comment)) != 0)
                        fatal_r(r, "Cannot load public key %s", argv[i]);
                r = ssh_krl_check_key(krl, k);
                printf("%s%s%s%s: %s\n", argv[i],
                    *comment ? " (" : "", comment, *comment ? ")" : "",
                    r == 0 ? "ok" : "REVOKED");
                if (r != 0)
                        ret = 1;
                sshkey_free(k);
                free(comment);
        }
        ssh_krl_free(krl);
        exit(ret);
}

static struct sshkey *
load_sign_key(const char *keypath, const struct sshkey *pubkey)
{
        size_t i, slen, plen = strlen(keypath);
        char *privpath = xstrdup(keypath);
        static const char * const suffixes[] = { "-cert.pub", ".pub", NULL };
        struct sshkey *ret = NULL, *privkey = NULL;
        int r, waspub = 0;
        struct stat st;

        /*
         * If passed a public key filename, then try to locate the corresponding
         * private key. This lets us specify certificates on the command-line
         * and have ssh-keygen find the appropriate private key.
         */
        for (i = 0; suffixes[i]; i++) {
                slen = strlen(suffixes[i]);
                if (plen <= slen ||
                    strcmp(privpath + plen - slen, suffixes[i]) != 0)
                        continue;
                privpath[plen - slen] = '\0';
                debug_f("%s looks like a public key, using private key "
                    "path %s instead", keypath, privpath);
                waspub = 1;
        }
        if (waspub && stat(privpath, &st) != 0 && errno == ENOENT)
                fatal("No private key found for public key \"%s\"", keypath);
        if ((r = sshkey_load_private(privpath, "", &privkey, NULL)) != 0 &&
            (r != SSH_ERR_KEY_WRONG_PASSPHRASE)) {
                debug_fr(r, "load private key \"%s\"", privpath);
                fatal("No private key found for \"%s\"", privpath);
        } else if (privkey == NULL)
                privkey = load_identity(privpath, NULL);

        if (!sshkey_equal_public(pubkey, privkey)) {
                error("Public key %s doesn't match private %s",
                    keypath, privpath);
                goto done;
        }
        if (sshkey_is_cert(pubkey) && !sshkey_is_cert(privkey)) {
                /*
                 * Graft the certificate onto the private key to make
                 * it capable of signing.
                 */
                if ((r = sshkey_to_certified(privkey)) != 0) {
                        error_fr(r, "sshkey_to_certified");
                        goto done;
                }
                if ((r = sshkey_cert_copy(pubkey, privkey)) != 0) {
                        error_fr(r, "sshkey_cert_copy");
                        goto done;
                }
        }
        /* success */
        ret = privkey;
        privkey = NULL;
 done:
        sshkey_free(privkey);
        free(privpath);
        return ret;
}

static int
sign_one(struct sshkey *signkey, const char *filename, int fd,
    const char *sig_namespace, const char *hashalg, sshsig_signer *signer,
    void *signer_ctx)
{
        struct sshbuf *sigbuf = NULL, *abuf = NULL;
        int r = SSH_ERR_INTERNAL_ERROR, wfd = -1, oerrno;
        char *wfile = NULL, *asig = NULL, *fp = NULL;
        char *pin = NULL, *prompt = NULL;

        if (!quiet) {
                if (fd == STDIN_FILENO)
                        fprintf(stderr, "Signing data on standard input\n");
                else
                        fprintf(stderr, "Signing file %s\n", filename);
        }
        if (signer == NULL && sshkey_is_sk(signkey)) {
                if ((signkey->sk_flags & SSH_SK_USER_VERIFICATION_REQD)) {
                        xasprintf(&prompt, "Enter PIN for %s key: ",
                            sshkey_type(signkey));
                        if ((pin = read_passphrase(prompt,
                            RP_ALLOW_STDIN)) == NULL)
                                fatal_f("couldn't read PIN");
                }
                if ((signkey->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
                        if ((fp = sshkey_fingerprint(signkey, fingerprint_hash,
                            SSH_FP_DEFAULT)) == NULL)
                                fatal_f("fingerprint failed");
                        fprintf(stderr, "Confirm user presence for key %s %s\n",
                            sshkey_type(signkey), fp);
                        free(fp);
                }
        }
        if ((r = sshsig_sign_fd(signkey, hashalg, sk_provider, pin,
            fd, sig_namespace, &sigbuf, signer, signer_ctx)) != 0) {
                error_r(r, "Signing %s failed", filename);
                goto out;
        }
        if ((r = sshsig_armor(sigbuf, &abuf)) != 0) {
                error_fr(r, "sshsig_armor");
                goto out;
        }
        if ((asig = sshbuf_dup_string(abuf)) == NULL) {
                error_f("buffer error");
                r = SSH_ERR_ALLOC_FAIL;
                goto out;
        }

        if (fd == STDIN_FILENO) {
                fputs(asig, stdout);
                fflush(stdout);
        } else {
                xasprintf(&wfile, "%s.sig", filename);
                if (confirm_overwrite(wfile)) {
                        if ((wfd = open(wfile, O_WRONLY|O_CREAT|O_TRUNC,
                            0666)) == -1) {
                                oerrno = errno;
                                error("Cannot open %s: %s",
                                    wfile, strerror(errno));
                                errno = oerrno;
                                r = SSH_ERR_SYSTEM_ERROR;
                                goto out;
                        }
                        if (atomicio(vwrite, wfd, asig,
                            strlen(asig)) != strlen(asig)) {
                                oerrno = errno;
                                error("Cannot write to %s: %s",
                                    wfile, strerror(errno));
                                errno = oerrno;
                                r = SSH_ERR_SYSTEM_ERROR;
                                goto out;
                        }
                        if (!quiet) {
                                fprintf(stderr, "Write signature to %s\n",
                                    wfile);
                        }
                }
        }
        /* success */
        r = 0;
 out:
        free(wfile);
        free(prompt);
        free(asig);
        if (pin != NULL)
                freezero(pin, strlen(pin));
        sshbuf_free(abuf);
        sshbuf_free(sigbuf);
        if (wfd != -1)
                close(wfd);
        return r;
}

static int
sig_process_opts(char * const *opts, size_t nopts, char **hashalgp,
    uint64_t *verify_timep, int *print_pubkey)
{
        size_t i;
        time_t now;

        if (verify_timep != NULL)
                *verify_timep = 0;
        if (print_pubkey != NULL)
                *print_pubkey = 0;
        if (hashalgp != NULL)
                *hashalgp = NULL;
        for (i = 0; i < nopts; i++) {
                if (hashalgp != NULL &&
                    strncasecmp(opts[i], "hashalg=", 8) == 0) {
                        *hashalgp = xstrdup(opts[i] + 8);
                } else if (verify_timep &&
                    strncasecmp(opts[i], "verify-time=", 12) == 0) {
                        if (parse_absolute_time(opts[i] + 12,
                            verify_timep) != 0 || *verify_timep == 0) {
                                error("Invalid \"verify-time\" option");
                                return SSH_ERR_INVALID_ARGUMENT;
                        }
                } else if (print_pubkey &&
                    strcasecmp(opts[i], "print-pubkey") == 0) {
                        *print_pubkey = 1;
                } else {
                        error("Invalid option \"%s\"", opts[i]);
                        return SSH_ERR_INVALID_ARGUMENT;
                }
        }
        if (verify_timep && *verify_timep == 0) {
                if ((now = time(NULL)) < 0) {
                        error("Time is before epoch");
                        return SSH_ERR_INVALID_ARGUMENT;
                }
                *verify_timep = (uint64_t)now;
        }
        return 0;
}


static int
sig_sign(const char *keypath, const char *sig_namespace, int require_agent,
    int argc, char **argv, char * const *opts, size_t nopts)
{
        int i, fd = -1, r, ret = -1;
        int agent_fd = -1;
        struct sshkey *pubkey = NULL, *privkey = NULL, *signkey = NULL;
        sshsig_signer *signer = NULL;
        char *hashalg = NULL;

        /* Check file arguments. */
        for (i = 0; i < argc; i++) {
                if (strcmp(argv[i], "-") != 0)
                        continue;
                if (i > 0 || argc > 1)
                        fatal("Cannot sign mix of paths and standard input");
        }

        if (sig_process_opts(opts, nopts, &hashalg, NULL, NULL) != 0)
                goto done; /* error already logged */

        if ((r = sshkey_load_public(keypath, &pubkey, NULL)) != 0) {
                error_r(r, "Couldn't load public key %s", keypath);
                goto done;
        }

        if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
                if (require_agent)
                        fatal("Couldn't get agent socket");
                debug_r(r, "Couldn't get agent socket");
        } else {
                if ((r = ssh_agent_has_key(agent_fd, pubkey)) == 0)
                        signer = agent_signer;
                else {
                        if (require_agent)
                                fatal("Couldn't find key in agent");
                        debug_r(r, "Couldn't find key in agent");
                }
        }

        if (signer == NULL) {
                /* Not using agent - try to load private key */
                if ((privkey = load_sign_key(keypath, pubkey)) == NULL)
                        goto done;
                signkey = privkey;
        } else {
                /* Will use key in agent */
                signkey = pubkey;
        }

        if (argc == 0) {
                if ((r = sign_one(signkey, "(stdin)", STDIN_FILENO,
                    sig_namespace, hashalg, signer, &agent_fd)) != 0)
                        goto done;
        } else {
                for (i = 0; i < argc; i++) {
                        if (strcmp(argv[i], "-") == 0)
                                fd = STDIN_FILENO;
                        else if ((fd = open(argv[i], O_RDONLY)) == -1) {
                                error("Cannot open %s for signing: %s",
                                    argv[i], strerror(errno));
                                goto done;
                        }
                        if ((r = sign_one(signkey, argv[i], fd, sig_namespace,
                            hashalg, signer, &agent_fd)) != 0)
                                goto done;
                        if (fd != STDIN_FILENO)
                                close(fd);
                        fd = -1;
                }
        }

        ret = 0;
done:
        if (fd != -1 && fd != STDIN_FILENO)
                close(fd);
        sshkey_free(pubkey);
        sshkey_free(privkey);
        free(hashalg);
        return ret;
}

static int
sig_verify(const char *signature, const char *sig_namespace,
    const char *principal, const char *allowed_keys, const char *revoked_keys,
    char * const *opts, size_t nopts)
{
        int r, ret = -1;
        int print_pubkey = 0;
        struct sshbuf *sigbuf = NULL, *abuf = NULL;
        struct sshkey *sign_key = NULL;
        char *fp = NULL;
        struct sshkey_sig_details *sig_details = NULL;
        uint64_t verify_time = 0;

        if (sig_process_opts(opts, nopts, NULL, &verify_time,
            &print_pubkey) != 0)
                goto done; /* error already logged */

        memset(&sig_details, 0, sizeof(sig_details));
        if ((r = sshbuf_load_file(signature, &abuf)) != 0) {
                error_r(r, "Couldn't read signature file");
                goto done;
        }

        if ((r = sshsig_dearmor(abuf, &sigbuf)) != 0) {
                error_fr(r, "sshsig_armor");
                goto done;
        }
        if ((r = sshsig_verify_fd(sigbuf, STDIN_FILENO, sig_namespace,
            &sign_key, &sig_details)) != 0)
                goto done; /* sshsig_verify() prints error */

        if ((fp = sshkey_fingerprint(sign_key, fingerprint_hash,
            SSH_FP_DEFAULT)) == NULL)
                fatal_f("sshkey_fingerprint failed");
        debug("Valid (unverified) signature from key %s", fp);
        if (sig_details != NULL) {
                debug2_f("signature details: counter = %u, flags = 0x%02x",
                    sig_details->sk_counter, sig_details->sk_flags);
        }
        free(fp);
        fp = NULL;

        if (revoked_keys != NULL) {
                if ((r = sshkey_check_revoked(sign_key, revoked_keys)) != 0) {
                        debug3_fr(r, "sshkey_check_revoked");
                        goto done;
                }
        }

        if (allowed_keys != NULL && (r = sshsig_check_allowed_keys(allowed_keys,
            sign_key, principal, sig_namespace, verify_time)) != 0) {
                debug3_fr(r, "sshsig_check_allowed_keys");
                goto done;
        }
        /* success */
        ret = 0;
done:
        if (!quiet) {
                if (ret == 0) {
                        if ((fp = sshkey_fingerprint(sign_key, fingerprint_hash,
                            SSH_FP_DEFAULT)) == NULL)
                                fatal_f("sshkey_fingerprint failed");
                        if (principal == NULL) {
                                printf("Good \"%s\" signature with %s key %s\n",
                                    sig_namespace, sshkey_type(sign_key), fp);

                        } else {
                                printf("Good \"%s\" signature for %s with %s key %s\n",
                                    sig_namespace, principal,
                                    sshkey_type(sign_key), fp);
                        }
                } else {
                        printf("Could not verify signature.\n");
                }
        }
        /* Print the signature key if requested */
        if (ret == 0 && print_pubkey && sign_key != NULL) {
                if ((r = sshkey_write(sign_key, stdout)) == 0)
                        fputc('\n', stdout);
                else {
                        error_r(r, "Could not print public key.\n");
                        ret = -1;
                }
        }
        sshbuf_free(sigbuf);
        sshbuf_free(abuf);
        sshkey_free(sign_key);
        sshkey_sig_details_free(sig_details);
        free(fp);
        return ret;
}

static int
sig_find_principals(const char *signature, const char *allowed_keys,
    char * const *opts, size_t nopts)
{
        int r, ret = -1;
        struct sshbuf *sigbuf = NULL, *abuf = NULL;
        struct sshkey *sign_key = NULL;
        char *principals = NULL, *cp, *tmp;
        uint64_t verify_time = 0;

        if (sig_process_opts(opts, nopts, NULL, &verify_time, NULL) != 0)
                goto done; /* error already logged */

        if ((r = sshbuf_load_file(signature, &abuf)) != 0) {
                error_r(r, "Couldn't read signature file");
                goto done;
        }
        if ((r = sshsig_dearmor(abuf, &sigbuf)) != 0) {
                error_fr(r, "sshsig_armor");
                goto done;
        }
        if ((r = sshsig_get_pubkey(sigbuf, &sign_key)) != 0) {
                error_fr(r, "sshsig_get_pubkey");
                goto done;
        }
        if ((r = sshsig_find_principals(allowed_keys, sign_key,
            verify_time, &principals)) != 0) {
                if (r != SSH_ERR_KEY_NOT_FOUND)
                        error_fr(r, "sshsig_find_principal");
                goto done;
        }
        ret = 0;
done:
        if (ret == 0 ) {
                /* Emit matching principals one per line */
                tmp = principals;
                while ((cp = strsep(&tmp, ",")) != NULL && *cp != '\0')
                        puts(cp);
        } else {
                fprintf(stderr, "No principal matched.\n");
        }
        sshbuf_free(sigbuf);
        sshbuf_free(abuf);
        sshkey_free(sign_key);
        free(principals);
        return ret;
}

static int
sig_match_principals(const char *allowed_keys, char *principal,
        char * const *opts, size_t nopts)
{
        int r;
        char **principals = NULL;
        size_t i, nprincipals = 0;

        if ((r = sig_process_opts(opts, nopts, NULL, NULL, NULL)) != 0)
                return r; /* error already logged */

        if ((r = sshsig_match_principals(allowed_keys, principal,
            &principals, &nprincipals)) != 0) {
                debug_f("match: %s", ssh_err(r));
                fprintf(stderr, "No principal matched.\n");
                return r;
        }
        for (i = 0; i < nprincipals; i++) {
                printf("%s\n", principals[i]);
                free(principals[i]);
        }
        free(principals);

        return 0;
}

static void
do_moduli_gen(const char *out_file, char **opts, size_t nopts)
{
#ifdef WITH_OPENSSL
        /* Moduli generation/screening */
        u_int32_t memory = 0;
        BIGNUM *start = NULL;
        int moduli_bits = 0;
        FILE *out;
        size_t i;
        const char *errstr;

        /* Parse options */
        for (i = 0; i < nopts; i++) {
                if (strncmp(opts[i], "memory=", 7) == 0) {
                        memory = (u_int32_t)strtonum(opts[i]+7, 1,
                            UINT_MAX, &errstr);
                        if (errstr) {
                                fatal("Memory limit is %s: %s",
                                    errstr, opts[i]+7);
                        }
                } else if (strncmp(opts[i], "start=", 6) == 0) {
                        /* XXX - also compare length against bits */
                        if (BN_hex2bn(&start, opts[i]+6) == 0)
                                fatal("Invalid start point.");
                } else if (strncmp(opts[i], "bits=", 5) == 0) {
                        moduli_bits = (int)strtonum(opts[i]+5, 1,
                            INT_MAX, &errstr);
                        if (errstr) {
                                fatal("Invalid number: %s (%s)",
                                        opts[i]+12, errstr);
                        }
                } else {
                        fatal("Option \"%s\" is unsupported for moduli "
                            "generation", opts[i]);
                }
        }

        if (strcmp(out_file, "-") == 0)
                out = stdout;
        else if ((out = fopen(out_file, "w")) == NULL) {
                fatal("Couldn't open modulus candidate file \"%s\": %s",
                    out_file, strerror(errno));
        }
        setvbuf(out, NULL, _IOLBF, 0);

        if (moduli_bits == 0)
                moduli_bits = DEFAULT_BITS;
        if (gen_candidates(out, memory, moduli_bits, start) != 0)
                fatal("modulus candidate generation failed");
#else /* WITH_OPENSSL */
        fatal("Moduli generation is not supported");
#endif /* WITH_OPENSSL */
}

static void
do_moduli_screen(const char *out_file, char **opts, size_t nopts)
{
#ifdef WITH_OPENSSL
        /* Moduli generation/screening */
        char *checkpoint = NULL;
        u_int32_t generator_wanted = 0;
        unsigned long start_lineno = 0, lines_to_process = 0;
        int prime_tests = 0;
        FILE *out, *in = stdin;
        size_t i;
        const char *errstr;

        /* Parse options */
        for (i = 0; i < nopts; i++) {
                if (strncmp(opts[i], "lines=", 6) == 0) {
                        lines_to_process = strtoul(opts[i]+6, NULL, 10);
                } else if (strncmp(opts[i], "start-line=", 11) == 0) {
                        start_lineno = strtoul(opts[i]+11, NULL, 10);
                } else if (strncmp(opts[i], "checkpoint=", 11) == 0) {
                        free(checkpoint);
                        checkpoint = xstrdup(opts[i]+11);
                } else if (strncmp(opts[i], "generator=", 10) == 0) {
                        generator_wanted = (u_int32_t)strtonum(
                            opts[i]+10, 1, UINT_MAX, &errstr);
                        if (errstr != NULL) {
                                fatal("Generator invalid: %s (%s)",
                                    opts[i]+10, errstr);
                        }
                } else if (strncmp(opts[i], "prime-tests=", 12) == 0) {
                        prime_tests = (int)strtonum(opts[i]+12, 1,
                            INT_MAX, &errstr);
                        if (errstr) {
                                fatal("Invalid number: %s (%s)",
                                        opts[i]+12, errstr);
                        }
                } else {
                        fatal("Option \"%s\" is unsupported for moduli "
                            "screening", opts[i]);
                }
        }

        if (have_identity && strcmp(identity_file, "-") != 0) {
                if ((in = fopen(identity_file, "r")) == NULL) {
                        fatal("Couldn't open modulus candidate "
                            "file \"%s\": %s", identity_file,
                            strerror(errno));
                }
        }

        if (strcmp(out_file, "-") == 0)
                out = stdout;
        else if ((out = fopen(out_file, "a")) == NULL) {
                fatal("Couldn't open moduli file \"%s\": %s",
                    out_file, strerror(errno));
        }
        setvbuf(out, NULL, _IOLBF, 0);
        if (prime_test(in, out, prime_tests == 0 ? 100 : prime_tests,
            generator_wanted, checkpoint,
            start_lineno, lines_to_process) != 0)
                fatal("modulus screening failed");
        if (in != stdin)
                (void)fclose(in);
        free(checkpoint);
#else /* WITH_OPENSSL */
        fatal("Moduli screening is not supported");
#endif /* WITH_OPENSSL */
}

/* Read and confirm a passphrase */
static char *
read_check_passphrase(const char *prompt1, const char *prompt2,
    const char *retry_prompt)
{
        char *passphrase1, *passphrase2;

        for (;;) {
                passphrase1 = read_passphrase(prompt1, RP_ALLOW_STDIN);
                passphrase2 = read_passphrase(prompt2, RP_ALLOW_STDIN);
                if (strcmp(passphrase1, passphrase2) == 0) {
                        freezero(passphrase2, strlen(passphrase2));
                        return passphrase1;
                }
                /* The passphrases do not match. Clear them and retry. */
                freezero(passphrase1, strlen(passphrase1));
                freezero(passphrase2, strlen(passphrase2));
                fputs(retry_prompt, stdout);
                fputc('\n', stdout);
                fflush(stdout);
        }
        /* NOTREACHED */
        return NULL;
}

static char *
private_key_passphrase(const char *path)
{
        char *prompt, *ret;

        if (identity_passphrase)
                return xstrdup(identity_passphrase);
        if (identity_new_passphrase)
                return xstrdup(identity_new_passphrase);

        xasprintf(&prompt, "Enter passphrase for \"%s\" "
            "(empty for no passphrase): ", path);
        ret = read_check_passphrase(prompt,
            "Enter same passphrase again: ",
            "Passphrases do not match.  Try again.");
        free(prompt);
        return ret;
}

static char *
sk_suffix(const char *application, const uint8_t *user, size_t userlen)
{
        char *ret, *cp;
        size_t slen, i;

        /* Trim off URL-like preamble */
        if (strncmp(application, "ssh://", 6) == 0)
                ret =  xstrdup(application + 6);
        else if (strncmp(application, "ssh:", 4) == 0)
                ret =  xstrdup(application + 4);
        else
                ret = xstrdup(application);

        /* Count trailing zeros in user */
        for (i = 0; i < userlen; i++) {
                if (user[userlen - i - 1] != 0)
                        break;
        }
        if (i >= userlen)
                return ret; /* user-id was default all-zeros */

        /* Append user-id, escaping non-UTF-8 characters */
        slen = userlen - i;
        if (asmprintf(&cp, INT_MAX, NULL, "%.*s", (int)slen, user) == -1)
                fatal_f("asmprintf failed");
        /* Don't emit a user-id that contains path or control characters */
        if (strchr(cp, '/') != NULL || strstr(cp, "..") != NULL ||
            strchr(cp, '\\') != NULL) {
                free(cp);
                cp = tohex(user, slen);
        }
        xextendf(&ret, "_", "%s", cp);
        free(cp);
        return ret;
}

static int
do_download_sk(const char *skprovider, const char *device)
{
        struct sshsk_resident_key **srks;
        size_t nsrks, i;
        int r, ret = -1;
        char *fp, *pin = NULL, *pass = NULL, *path, *pubpath;
        const char *ext;
        struct sshkey *key;

        if (skprovider == NULL)
                fatal("Cannot download keys without provider");

        pin = read_passphrase("Enter PIN for authenticator: ", RP_ALLOW_STDIN);
        if (!quiet) {
                printf("You may need to touch your authenticator "
                    "to authorize key download.\n");
        }
        if ((r = sshsk_load_resident(skprovider, device, pin, 0,
            &srks, &nsrks)) != 0) {
                if (pin != NULL)
                        freezero(pin, strlen(pin));
                error_r(r, "Unable to load resident keys");
                return -1;
        }
        if (nsrks == 0)
                logit("No keys to download");
        if (pin != NULL)
                freezero(pin, strlen(pin));

        for (i = 0; i < nsrks; i++) {
                key = srks[i]->key;
                if (key->type != KEY_ECDSA_SK && key->type != KEY_ED25519_SK) {
                        error("Unsupported key type %s (%d)",
                            sshkey_type(key), key->type);
                        continue;
                }
                if ((fp = sshkey_fingerprint(key, fingerprint_hash,
                    SSH_FP_DEFAULT)) == NULL)
                        fatal_f("sshkey_fingerprint failed");
                debug_f("key %zu: %s %s %s (flags 0x%02x)", i,
                    sshkey_type(key), fp, key->sk_application, key->sk_flags);
                ext = sk_suffix(key->sk_application,
                    srks[i]->user_id, srks[i]->user_id_len);
                xasprintf(&path, "id_%s_rk%s%s",
                    key->type == KEY_ECDSA_SK ? "ecdsa_sk" : "ed25519_sk",
                    *ext == '\0' ? "" : "_", ext);

                /* If the file already exists, ask the user to confirm. */
                if (!confirm_overwrite(path)) {
                        free(path);
                        break;
                }

                /* Save the key with the application string as the comment */
                if (pass == NULL)
                        pass = private_key_passphrase(path);
                if ((r = sshkey_save_private(key, path, pass,
                    key->sk_application, private_key_format,
                    openssh_format_cipher, rounds)) != 0) {
                        error_r(r, "Saving key \"%s\" failed", path);
                        free(path);
                        break;
                }
                if (!quiet) {
                        printf("Saved %s key%s%s to %s\n", sshkey_type(key),
                            *ext != '\0' ? " " : "",
                            *ext != '\0' ? key->sk_application : "",
                            path);
                }

                /* Save public key too */
                xasprintf(&pubpath, "%s.pub", path);
                free(path);
                if ((r = sshkey_save_public(key, pubpath,
                    key->sk_application)) != 0) {
                        error_r(r, "Saving public key \"%s\" failed", pubpath);
                        free(pubpath);
                        break;
                }
                free(pubpath);
        }

        if (i >= nsrks)
                ret = 0; /* success */
        if (pass != NULL)
                freezero(pass, strlen(pass));
        sshsk_free_resident_keys(srks, nsrks);
        return ret;
}

static void
save_attestation(struct sshbuf *attest, const char *path)
{
        mode_t omask;
        int r;

        if (path == NULL)
                return; /* nothing to do */
        if (attest == NULL || sshbuf_len(attest) == 0)
                fatal("Enrollment did not return attestation data");
        omask = umask(077);
        r = sshbuf_write_file(path, attest);
        umask(omask);
        if (r != 0)
                fatal_r(r, "Unable to write attestation data \"%s\"", path);
        if (!quiet)
                printf("Your FIDO attestation certificate has been saved in "
                    "%s\n", path);
}

static int
confirm_sk_overwrite(const char *application, const char *user)
{
        char yesno[3];

        printf("A resident key scoped to '%s' with user id '%s' already "
            "exists.\n", application == NULL ? "ssh:" : application,
            user == NULL ? "null" : user);
        printf("Overwrite key in token (y/n)? ");
        fflush(stdout);
        if (fgets(yesno, sizeof(yesno), stdin) == NULL)
                return 0;
        if (yesno[0] != 'y' && yesno[0] != 'Y')
                return 0;
        return 1;
}

static void
usage(void)
{
        fprintf(stderr,
            "usage: ssh-keygen [-q] [-a rounds] [-b bits] [-C comment] [-f output_keyfile]\n"
            "                  [-m format] [-N new_passphrase] [-O option]\n"
            "                  [-t dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa]\n"
            "                  [-w provider] [-Z cipher]\n"
            "       ssh-keygen -p [-a rounds] [-f keyfile] [-m format] [-N new_passphrase]\n"
            "                   [-P old_passphrase] [-Z cipher]\n"
#ifdef WITH_OPENSSL
            "       ssh-keygen -i [-f input_keyfile] [-m key_format]\n"
            "       ssh-keygen -e [-f input_keyfile] [-m key_format]\n"
#endif
            "       ssh-keygen -y [-f input_keyfile]\n"
            "       ssh-keygen -c [-a rounds] [-C comment] [-f keyfile] [-P passphrase]\n"
            "       ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile]\n"
            "       ssh-keygen -B [-f input_keyfile]\n");
#ifdef ENABLE_PKCS11
        fprintf(stderr,
            "       ssh-keygen -D pkcs11\n");
#endif
        fprintf(stderr,
            "       ssh-keygen -F hostname [-lv] [-f known_hosts_file]\n"
            "       ssh-keygen -H [-f known_hosts_file]\n"
            "       ssh-keygen -K [-a rounds] [-w provider]\n"
            "       ssh-keygen -R hostname [-f known_hosts_file]\n"
            "       ssh-keygen -r hostname [-g] [-f input_keyfile]\n"
#ifdef WITH_OPENSSL
            "       ssh-keygen -M generate [-O option] output_file\n"
            "       ssh-keygen -M screen [-f input_file] [-O option] output_file\n"
#endif
            "       ssh-keygen -I certificate_identity -s ca_key [-hU] [-D pkcs11_provider]\n"
            "                  [-n principals] [-O option] [-V validity_interval]\n"
            "                  [-z serial_number] file ...\n"
            "       ssh-keygen -L [-f input_keyfile]\n"
            "       ssh-keygen -A [-a rounds] [-f prefix_path]\n"
            "       ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number]\n"
            "                  file ...\n"
            "       ssh-keygen -Q [-l] -f krl_file [file ...]\n"
            "       ssh-keygen -Y find-principals -s signature_file -f allowed_signers_file\n"
            "       ssh-keygen -Y match-principals -I signer_identity -f allowed_signers_file\n"
            "       ssh-keygen -Y check-novalidate -n namespace -s signature_file\n"
            "       ssh-keygen -Y sign -f key_file -n namespace file [-O option] ...\n"
            "       ssh-keygen -Y verify -f allowed_signers_file -I signer_identity\n"
            "                  -n namespace -s signature_file [-r krl_file] [-O option]\n");
        exit(1);
}

/*
 * Main program for key management.
 */
int
main(int argc, char **argv)
{
        char comment[1024], *passphrase = NULL;
        char *rr_hostname = NULL, *ep, *fp, *ra;
        struct sshkey *private, *public;
        struct passwd *pw;
        int r, opt, type;
        int change_passphrase = 0, change_comment = 0, show_cert = 0;
        int find_host = 0, delete_host = 0, hash_hosts = 0;
        int gen_all_hostkeys = 0, gen_krl = 0, update_krl = 0, check_krl = 0;
        int prefer_agent = 0, convert_to = 0, convert_from = 0;
        int print_public = 0, print_generic = 0, cert_serial_autoinc = 0;
        int do_gen_candidates = 0, do_screen_candidates = 0, download_sk = 0;
        unsigned long long cert_serial = 0;
        char *identity_comment = NULL, *ca_key_path = NULL, **opts = NULL;
        char *sk_application = NULL, *sk_device = NULL, *sk_user = NULL;
        char *sk_attestation_path = NULL;
        struct sshbuf *challenge = NULL, *attest = NULL;
        size_t i, nopts = 0;
        u_int32_t bits = 0;
        uint8_t sk_flags = SSH_SK_USER_PRESENCE_REQD;
        const char *errstr;
        int log_level = SYSLOG_LEVEL_INFO;
        char *sign_op = NULL;

        extern int optind;
        extern char *optarg;

        /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
        sanitise_stdfd();

        __progname = ssh_get_progname(argv[0]);

        seed_rng();

        log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);

        msetlocale();

        /* we need this for the home * directory.  */
        pw = getpwuid(getuid());
        if (!pw)
                fatal("No user exists for uid %lu", (u_long)getuid());
        pw = pwcopy(pw);
        if (gethostname(hostname, sizeof(hostname)) == -1)
                fatal("gethostname: %s", strerror(errno));

        sk_provider = getenv("SSH_SK_PROVIDER");

        /* Remaining characters: dGjJSTWx */
        while ((opt = getopt(argc, argv, "ABHKLQUXceghiklopquvy"
            "C:D:E:F:I:M:N:O:P:R:V:Y:Z:"
            "a:b:f:g:m:n:r:s:t:w:z:")) != -1) {
                switch (opt) {
                case 'A':
                        gen_all_hostkeys = 1;
                        break;
                case 'b':
                        bits = (u_int32_t)strtonum(optarg, 1, UINT32_MAX,
                            &errstr);
                        if (errstr)
                                fatal("Bits has bad value %s (%s)",
                                        optarg, errstr);
                        break;
                case 'E':
                        fingerprint_hash = ssh_digest_alg_by_name(optarg);
                        if (fingerprint_hash == -1)
                                fatal("Invalid hash algorithm \"%s\"", optarg);
                        break;
                case 'F':
                        find_host = 1;
                        rr_hostname = optarg;
                        break;
                case 'H':
                        hash_hosts = 1;
                        break;
                case 'I':
                        cert_key_id = optarg;
                        break;
                case 'R':
                        delete_host = 1;
                        rr_hostname = optarg;
                        break;
                case 'L':
                        show_cert = 1;
                        break;
                case 'l':
                        print_fingerprint = 1;
                        break;
                case 'B':
                        print_bubblebabble = 1;
                        break;
                case 'm':
                        if (strcasecmp(optarg, "RFC4716") == 0 ||
                            strcasecmp(optarg, "ssh2") == 0) {
                                convert_format = FMT_RFC4716;
                                break;
                        }
                        if (strcasecmp(optarg, "PKCS8") == 0) {
                                convert_format = FMT_PKCS8;
                                private_key_format = SSHKEY_PRIVATE_PKCS8;
                                break;
                        }
                        if (strcasecmp(optarg, "PEM") == 0) {
                                convert_format = FMT_PEM;
                                private_key_format = SSHKEY_PRIVATE_PEM;
                                break;
                        }
                        fatal("Unsupported conversion format \"%s\"", optarg);
                case 'n':
                        cert_principals = optarg;
                        break;
                case 'o':
                        /* no-op; new format is already the default */
                        break;
                case 'p':
                        change_passphrase = 1;
                        break;
                case 'c':
                        change_comment = 1;
                        break;
                case 'f':
                        if (strlcpy(identity_file, optarg,
                            sizeof(identity_file)) >= sizeof(identity_file))
                                fatal("Identity filename too long");
                        have_identity = 1;
                        break;
                case 'g':
                        print_generic = 1;
                        break;
                case 'K':
                        download_sk = 1;
                        break;
                case 'P':
                        identity_passphrase = optarg;
                        break;
                case 'N':
                        identity_new_passphrase = optarg;
                        break;
                case 'Q':
                        check_krl = 1;
                        break;
                case 'O':
                        opts = xrecallocarray(opts, nopts, nopts + 1,
                            sizeof(*opts));
                        opts[nopts++] = xstrdup(optarg);
                        break;
                case 'Z':
                        openssh_format_cipher = optarg;
                        if (cipher_by_name(openssh_format_cipher) == NULL)
                                fatal("Invalid OpenSSH-format cipher '%s'",
                                    openssh_format_cipher);
                        break;
                case 'C':
                        identity_comment = optarg;
                        break;
                case 'q':
                        quiet = 1;
                        break;
                case 'e':
                        /* export key */
                        convert_to = 1;
                        break;
                case 'h':
                        cert_key_type = SSH2_CERT_TYPE_HOST;
                        certflags_flags = 0;
                        break;
                case 'k':
                        gen_krl = 1;
                        break;
                case 'i':
                case 'X':
                        /* import key */
                        convert_from = 1;
                        break;
                case 'y':
                        print_public = 1;
                        break;
                case 's':
                        ca_key_path = optarg;
                        break;
                case 't':
                        key_type_name = optarg;
                        break;
                case 'D':
                        pkcs11provider = optarg;
                        break;
                case 'U':
                        prefer_agent = 1;
                        break;
                case 'u':
                        update_krl = 1;
                        break;
                case 'v':
                        if (log_level == SYSLOG_LEVEL_INFO)
                                log_level = SYSLOG_LEVEL_DEBUG1;
                        else {
                                if (log_level >= SYSLOG_LEVEL_DEBUG1 &&
                                    log_level < SYSLOG_LEVEL_DEBUG3)
                                        log_level++;
                        }
                        break;
                case 'r':
                        rr_hostname = optarg;
                        break;
                case 'a':
                        rounds = (int)strtonum(optarg, 1, INT_MAX, &errstr);
                        if (errstr)
                                fatal("Invalid number: %s (%s)",
                                        optarg, errstr);
                        break;
                case 'V':
                        parse_cert_times(optarg);
                        break;
                case 'Y':
                        sign_op = optarg;
                        break;
                case 'w':
                        sk_provider = optarg;
                        break;
                case 'z':
                        errno = 0;
                        if (*optarg == '+') {
                                cert_serial_autoinc = 1;
                                optarg++;
                        }
                        cert_serial = strtoull(optarg, &ep, 10);
                        if (*optarg < '0' || *optarg > '9' || *ep != '\0' ||
                            (errno == ERANGE && cert_serial == ULLONG_MAX))
                                fatal("Invalid serial number \"%s\"", optarg);
                        break;
                case 'M':
                        if (strcmp(optarg, "generate") == 0)
                                do_gen_candidates = 1;
                        else if (strcmp(optarg, "screen") == 0)
                                do_screen_candidates = 1;
                        else
                                fatal("Unsupported moduli option %s", optarg);
                        break;
                default:
                        usage();
                }
        }

#ifdef ENABLE_SK_INTERNAL
        if (sk_provider == NULL)
                sk_provider = "internal";
#endif

        /* reinit */
        log_init(argv[0], log_level, SYSLOG_FACILITY_USER, 1);

        argv += optind;
        argc -= optind;

        if (sign_op != NULL) {
                if (strncmp(sign_op, "find-principals", 15) == 0) {
                        if (ca_key_path == NULL) {
                                error("Too few arguments for find-principals:"
                                    "missing signature file");
                                exit(1);
                        }
                        if (!have_identity) {
                                error("Too few arguments for find-principals:"
                                    "missing allowed keys file");
                                exit(1);
                        }
                        return sig_find_principals(ca_key_path, identity_file,
                            opts, nopts);
                } else if (strncmp(sign_op, "match-principals", 16) == 0) {
                        if (!have_identity) {
                                error("Too few arguments for match-principals:"
                                    "missing allowed keys file");
                                exit(1);
                        }
                        if (cert_key_id == NULL) {
                                error("Too few arguments for match-principals: "
                                    "missing principal ID");
                                exit(1);
                        }
                        return sig_match_principals(identity_file, cert_key_id,
                            opts, nopts);
                } else if (strncmp(sign_op, "sign", 4) == 0) {
                        /* NB. cert_principals is actually namespace, via -n */
                        if (cert_principals == NULL ||
                            *cert_principals == '\0') {
                                error("Too few arguments for sign: "
                                    "missing namespace");
                                exit(1);
                        }
                        if (!have_identity) {
                                error("Too few arguments for sign: "
                                    "missing key");
                                exit(1);
                        }
                        return sig_sign(identity_file, cert_principals,
                            prefer_agent, argc, argv, opts, nopts);
                } else if (strncmp(sign_op, "check-novalidate", 16) == 0) {
                        /* NB. cert_principals is actually namespace, via -n */
                        if (cert_principals == NULL ||
                            *cert_principals == '\0') {
                                error("Too few arguments for check-novalidate: "
                                    "missing namespace");
                                exit(1);
                        }
                        if (ca_key_path == NULL) {
                                error("Too few arguments for check-novalidate: "
                                    "missing signature file");
                                exit(1);
                        }
                        return sig_verify(ca_key_path, cert_principals,
                            NULL, NULL, NULL, opts, nopts);
                } else if (strncmp(sign_op, "verify", 6) == 0) {
                        /* NB. cert_principals is actually namespace, via -n */
                        if (cert_principals == NULL ||
                            *cert_principals == '\0') {
                                error("Too few arguments for verify: "
                                    "missing namespace");
                                exit(1);
                        }
                        if (ca_key_path == NULL) {
                                error("Too few arguments for verify: "
                                    "missing signature file");
                                exit(1);
                        }
                        if (!have_identity) {
                                error("Too few arguments for sign: "
                                    "missing allowed keys file");
                                exit(1);
                        }
                        if (cert_key_id == NULL) {
                                error("Too few arguments for verify: "
                                    "missing principal identity");
                                exit(1);
                        }
                        return sig_verify(ca_key_path, cert_principals,
                            cert_key_id, identity_file, rr_hostname,
                            opts, nopts);
                }
                error("Unsupported operation for -Y: \"%s\"", sign_op);
                usage();
                /* NOTREACHED */
        }

        if (ca_key_path != NULL) {
                if (argc < 1 && !gen_krl) {
                        error("Too few arguments.");
                        usage();
                }
        } else if (argc > 0 && !gen_krl && !check_krl &&
            !do_gen_candidates && !do_screen_candidates) {
                error("Too many arguments.");
                usage();
        }
        if (change_passphrase && change_comment) {
                error("Can only have one of -p and -c.");
                usage();
        }
        if (print_fingerprint && (delete_host || hash_hosts)) {
                error("Cannot use -l with -H or -R.");
                usage();
        }
        if (gen_krl) {
                do_gen_krl(pw, update_krl, ca_key_path,
                    cert_serial, identity_comment, argc, argv);
                return (0);
        }
        if (check_krl) {
                do_check_krl(pw, print_fingerprint, argc, argv);
                return (0);
        }
        if (ca_key_path != NULL) {
                if (cert_key_id == NULL)
                        fatal("Must specify key id (-I) when certifying");
                for (i = 0; i < nopts; i++)
                        add_cert_option(opts[i]);
                do_ca_sign(pw, ca_key_path, prefer_agent,
                    cert_serial, cert_serial_autoinc, argc, argv);
        }
        if (show_cert)
                do_show_cert(pw);
        if (delete_host || hash_hosts || find_host) {
                do_known_hosts(pw, rr_hostname, find_host,
                    delete_host, hash_hosts);
        }
        if (pkcs11provider != NULL)
                do_download(pw);
        if (download_sk) {
                for (i = 0; i < nopts; i++) {
                        if (strncasecmp(opts[i], "device=", 7) == 0) {
                                sk_device = xstrdup(opts[i] + 7);
                        } else {
                                fatal("Option \"%s\" is unsupported for "
                                    "FIDO authenticator download", opts[i]);
                        }
                }
                return do_download_sk(sk_provider, sk_device);
        }
        if (print_fingerprint || print_bubblebabble)
                do_fingerprint(pw);
        if (change_passphrase)
                do_change_passphrase(pw);
        if (change_comment)
                do_change_comment(pw, identity_comment);
#ifdef WITH_OPENSSL
        if (convert_to)
                do_convert_to(pw);
        if (convert_from)
                do_convert_from(pw);
#else /* WITH_OPENSSL */
        if (convert_to || convert_from)
                fatal("key conversion disabled at compile time");
#endif /* WITH_OPENSSL */
        if (print_public)
                do_print_public(pw);
        if (rr_hostname != NULL) {
                unsigned int n = 0;

                if (have_identity) {
                        n = do_print_resource_record(pw, identity_file,
                            rr_hostname, print_generic, opts, nopts);
                        if (n == 0)
                                fatal("%s: %s", identity_file, strerror(errno));
                        exit(0);
                } else {

                        n += do_print_resource_record(pw,
                            _PATH_HOST_RSA_KEY_FILE, rr_hostname,
                            print_generic, opts, nopts);
#ifdef WITH_DSA
                        n += do_print_resource_record(pw,
                            _PATH_HOST_DSA_KEY_FILE, rr_hostname,
                            print_generic, opts, nopts);
#endif
                        n += do_print_resource_record(pw,
                            _PATH_HOST_ECDSA_KEY_FILE, rr_hostname,
                            print_generic, opts, nopts);
                        n += do_print_resource_record(pw,
                            _PATH_HOST_ED25519_KEY_FILE, rr_hostname,
                            print_generic, opts, nopts);
                        n += do_print_resource_record(pw,
                            _PATH_HOST_XMSS_KEY_FILE, rr_hostname,
                            print_generic, opts, nopts);
                        if (n == 0)
                                fatal("no keys found.");
                        exit(0);
                }
        }

        if (do_gen_candidates || do_screen_candidates) {
                if (argc <= 0)
                        fatal("No output file specified");
                else if (argc > 1)
                        fatal("Too many output files specified");
        }
        if (do_gen_candidates) {
                do_moduli_gen(argv[0], opts, nopts);
                return 0;
        }
        if (do_screen_candidates) {
                do_moduli_screen(argv[0], opts, nopts);
                return 0;
        }

        if (gen_all_hostkeys) {
                do_gen_all_hostkeys(pw);
                return (0);
        }

        if (key_type_name == NULL)
                key_type_name = DEFAULT_KEY_TYPE_NAME;

        type = sshkey_type_from_shortname(key_type_name);
        type_bits_valid(type, key_type_name, &bits);

        if (!quiet)
                printf("Generating public/private %s key pair.\n",
                    key_type_name);
        switch (type) {
        case KEY_ECDSA_SK:
        case KEY_ED25519_SK:
                for (i = 0; i < nopts; i++) {
                        if (strcasecmp(opts[i], "no-touch-required") == 0) {
                                sk_flags &= ~SSH_SK_USER_PRESENCE_REQD;
                        } else if (strcasecmp(opts[i], "verify-required") == 0) {
                                sk_flags |= SSH_SK_USER_VERIFICATION_REQD;
                        } else if (strcasecmp(opts[i], "resident") == 0) {
                                sk_flags |= SSH_SK_RESIDENT_KEY;
                        } else if (strncasecmp(opts[i], "device=", 7) == 0) {
                                sk_device = xstrdup(opts[i] + 7);
                        } else if (strncasecmp(opts[i], "user=", 5) == 0) {
                                sk_user = xstrdup(opts[i] + 5);
                        } else if (strncasecmp(opts[i], "challenge=", 10) == 0) {
                                if ((r = sshbuf_load_file(opts[i] + 10,
                                    &challenge)) != 0) {
                                        fatal_r(r, "Unable to load FIDO "
                                            "enrollment challenge \"%s\"",
                                            opts[i] + 10);
                                }
                        } else if (strncasecmp(opts[i],
                            "write-attestation=", 18) == 0) {
                                sk_attestation_path = opts[i] + 18;
                        } else if (strncasecmp(opts[i],
                            "application=", 12) == 0) {
                                sk_application = xstrdup(opts[i] + 12);
                                if (strncmp(sk_application, "ssh:", 4) != 0) {
                                        fatal("FIDO application string must "
                                            "begin with \"ssh:\"");
                                }
                        } else {
                                fatal("Option \"%s\" is unsupported for "
                                    "FIDO authenticator enrollment", opts[i]);
                        }
                }
                if ((attest = sshbuf_new()) == NULL)
                        fatal("sshbuf_new failed");
                r = 0;
                for (i = 0 ;;) {
                        if (!quiet) {
                                printf("You may need to touch your "
                                    "authenticator%s to authorize key "
                                    "generation.\n",
                                    r == 0 ? "" : " again");
                        }
                        fflush(stdout);
                        r = sshsk_enroll(type, sk_provider, sk_device,
                            sk_application == NULL ? "ssh:" : sk_application,
                            sk_user, sk_flags, passphrase, challenge,
                            &private, attest);
                        if (r == 0)
                                break;
                        if (r == SSH_ERR_KEY_BAD_PERMISSIONS &&
                            (sk_flags & SSH_SK_RESIDENT_KEY) != 0 &&
                            (sk_flags & SSH_SK_FORCE_OPERATION) == 0 &&
                            confirm_sk_overwrite(sk_application, sk_user)) {
                                sk_flags |= SSH_SK_FORCE_OPERATION;
                                continue;
                        }
                        if (r != SSH_ERR_KEY_WRONG_PASSPHRASE)
                                fatal_r(r, "Key enrollment failed");
                        else if (passphrase != NULL) {
                                error("PIN incorrect");
                                freezero(passphrase, strlen(passphrase));
                                passphrase = NULL;
                        }
                        if (++i >= 3)
                                fatal("Too many incorrect PINs");
                        passphrase = read_passphrase("Enter PIN for "
                            "authenticator: ", RP_ALLOW_STDIN);
                }
                if (passphrase != NULL) {
                        freezero(passphrase, strlen(passphrase));
                        passphrase = NULL;
                }
                break;
        default:
                if ((r = sshkey_generate(type, bits, &private)) != 0)
                        fatal("sshkey_generate failed");
                break;
        }
        if ((r = sshkey_from_private(private, &public)) != 0)
                fatal_r(r, "sshkey_from_private");

        if (!have_identity)
                ask_filename(pw, "Enter file in which to save the key");

        /* Create ~/.ssh directory if it doesn't already exist. */
        hostfile_create_user_ssh_dir(identity_file, !quiet);

        /* If the file already exists, ask the user to confirm. */
        if (!confirm_overwrite(identity_file))
                exit(1);

        /* Determine the passphrase for the private key */
        passphrase = private_key_passphrase(identity_file);
        if (identity_comment) {
                strlcpy(comment, identity_comment, sizeof(comment));
        } else {
                /* Create default comment field for the passphrase. */
                snprintf(comment, sizeof comment, "%s@%s", pw->pw_name, hostname);
        }

        /* Save the key with the given passphrase and comment. */
        if ((r = sshkey_save_private(private, identity_file, passphrase,
            comment, private_key_format, openssh_format_cipher, rounds)) != 0) {
                error_r(r, "Saving key \"%s\" failed", identity_file);
                freezero(passphrase, strlen(passphrase));
                exit(1);
        }
        freezero(passphrase, strlen(passphrase));
        sshkey_free(private);

        if (!quiet) {
                printf("Your identification has been saved in %s\n",
                    identity_file);
        }

        strlcat(identity_file, ".pub", sizeof(identity_file));
        if ((r = sshkey_save_public(public, identity_file, comment)) != 0)
                fatal_r(r, "Unable to save public key to %s", identity_file);

        if (!quiet) {
                fp = sshkey_fingerprint(public, fingerprint_hash,
                    SSH_FP_DEFAULT);
                ra = sshkey_fingerprint(public, fingerprint_hash,
                    SSH_FP_RANDOMART);
                if (fp == NULL || ra == NULL)
                        fatal("sshkey_fingerprint failed");
                printf("Your public key has been saved in %s\n",
                    identity_file);
                printf("The key fingerprint is:\n");
                printf("%s %s\n", fp, comment);
                printf("The key's randomart image is:\n");
                printf("%s\n", ra);
                free(ra);
                free(fp);
        }

        if (sk_attestation_path != NULL)
                save_attestation(attest, sk_attestation_path);

        sshbuf_free(attest);
        sshkey_free(public);

        exit(0);
}