/*      $NetBSD: plainrsa-gen.c,v 1.8 2025/03/08 16:39:08 christos Exp $        */

/* Id: plainrsa-gen.c,v 1.6 2005/04/21 09:08:40 monas Exp */
/*
 * Copyright (C) 2004 SuSE Linux AG, Nuernberg, Germany.
 * Contributed by: Michal Ludvig <mludvig@suse.cz>, SUSE Labs
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/* This file contains a generator for FreeS/WAN-style ipsec.secrets RSA keys. */

#include "config.h"

#include <stdio.h>
#include <string.h>
#include <errno.h>

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

#include <openssl/bio.h>
#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/objects.h>
#include <openssl/pem.h>
#include <openssl/rsa.h>
#include <openssl/evp.h>
#ifdef HAVE_OPENSSL_ENGINE_H
#include <openssl/engine.h>
#endif

#include "misc.h"
#include "vmbuf.h"
#include "plog.h"
#include "crypto_openssl.h"

#include "package_version.h"

#define DEFAULT_PUBEXP RSA_F4

static void
usage(char *argv0)
{
        fprintf(stderr, "Plain RSA key generator, part of %s\n", TOP_PACKAGE_STRING);
        fprintf(stderr, "By Michal Ludvig (http://www.logix.cz/michal)\n");
        fprintf(stderr, "\n");
        fprintf(stderr, "Usage: %s [options]\n", argv0);
        fprintf(stderr, "\n");
        fprintf(stderr, "  -b bits       Generate <bits> long RSA key (default=1024)\n");
        fprintf(stderr, "  -e pubexp     Public exponent to use (default=%#lx)\n", DEFAULT_PUBEXP);
        fprintf(stderr, "  -f filename   Filename to store the key to (default=stdout)\n");
        fprintf(stderr, "  -i filename   Input source for format conversion\n");
        fprintf(stderr, "  -h            Help\n");
        fprintf(stderr, "\n");
        fprintf(stderr, "Report bugs to <ipsec-tools-devel@lists.sourceforge.net>\n");
        exit(1);
}

/*
 * See RFC 2065, section 3.5 for details about the output format.
 */
static vchar_t *
mix_b64_pubkey(const RSA *key)
{
        char *binbuf;
        long binlen, ret;
        
        binlen = 1 + BN_num_bytes(RSA_get0_e(key)) + BN_num_bytes(RSA_get0_n(key));
        binbuf = malloc(binlen);
        memset(binbuf, 0, binlen);
        binbuf[0] = BN_bn2bin(RSA_get0_e(key), (unsigned char *) &binbuf[1]);
        ret = BN_bn2bin(RSA_get0_n(key), (unsigned char *) (&binbuf[binbuf[0] + 1]));
        if (1 + binbuf[0] + ret != binlen) {
                plog(LLV_ERROR, LOCATION, NULL,
                     "Pubkey generation failed. This is really strange...\n");
                return NULL;
        }

        return base64_encode(binbuf, binlen);
}

static char *
lowercase(char *input)
{
        for (char *ptr = input; *ptr; ptr++) {
                if (*ptr >= 'A' && *ptr <= 'F')
                        *ptr -= 'A' - 'a';
        }

        return input;
}

static int
print_rsa_key(FILE *fp, const RSA *key)
{
        vchar_t *pubkey64 = NULL;

        pubkey64 = mix_b64_pubkey(key);
        if (!pubkey64) {
                fprintf(stderr, "mix_b64_pubkey(): %s\n", eay_strerror());
                return -1;
        }
        
        fprintf(fp, "# : PUB 0s%s\n", pubkey64->v);
        fprintf(fp, ": RSA\t{\n");
        fprintf(fp, "\t# RSA %d bits\n", BN_num_bits(RSA_get0_n(key)));
        fprintf(fp, "\t# pubkey=0s%s\n", pubkey64->v);
        fprintf(fp, "\tModulus: 0x%s\n", lowercase(BN_bn2hex(RSA_get0_n(key))));
        fprintf(fp, "\tPublicExponent: 0x%s\n", lowercase(BN_bn2hex(RSA_get0_e(key))));
        fprintf(fp, "\tPrivateExponent: 0x%s\n", lowercase(BN_bn2hex(RSA_get0_d(key))));
        fprintf(fp, "\tPrime1: 0x%s\n", lowercase(BN_bn2hex(RSA_get0_p(key))));
        fprintf(fp, "\tPrime2: 0x%s\n", lowercase(BN_bn2hex(RSA_get0_q(key))));
        fprintf(fp, "\tExponent1: 0x%s\n", lowercase(BN_bn2hex(RSA_get0_dmp1(key))));
        fprintf(fp, "\tExponent2: 0x%s\n", lowercase(BN_bn2hex(RSA_get0_dmq1(key))));
        fprintf(fp, "\tCoefficient: 0x%s\n", lowercase(BN_bn2hex(RSA_get0_iqmp(key))));
        fprintf(fp, "  }\n");

        vfree(pubkey64);
        return 0;
}

static int
print_public_rsa_key(FILE *fp, const RSA *key)
{
        vchar_t *pubkey64 = NULL;

        pubkey64 = mix_b64_pubkey(key);
        if (!pubkey64) {
                fprintf(stderr, "mix_b64_pubkey(): %s\n", eay_strerror());
                return -1;
        }
        
        fprintf(fp, ": PUB 0s%s\n", pubkey64->v);

        vfree(pubkey64);
        return 0;
}

static int
convert_rsa_key(FILE *fpout, FILE *fpin)
{
        int ret;
        RSA *key;

        key = PEM_read_RSAPrivateKey(fpin, NULL, NULL, NULL);
        if (key) {
                ret = print_rsa_key(fpout, key);
                RSA_free(key);

                return ret;
        }
        
        rewind(fpin);

        key = PEM_read_RSA_PUBKEY(fpin, NULL, NULL, NULL);
        if (key) {
                ret = print_public_rsa_key(fpout, key);
                RSA_free(key);

                return ret;
        }

        /* Implement parsing of input stream containing
         * private or public "plainrsa" formatted text.
         * Convert the result to PEM formatted output.
         *
         * This seemingly needs manual use of prsaparse().
         * An expert ought to do this. */

        fprintf(stderr, "convert_rsa_key: %s\n", "Only conversion from PEM at this time");
        return -1;
}

static int
gen_rsa_key(FILE *fp, size_t bits, unsigned long exp)
{
        int ret;
        RSA *key;
        BIGNUM *e;

        key = RSA_new();
        e = BN_new();
        BN_set_word(e, exp);

        if (1 != RSA_generate_key_ex(key, bits, e, NULL)) {
                fprintf(stderr, "RSA_generate_key(): %s\n", eay_strerror());
                return -1;
        }

        ret = print_rsa_key(fp, key);
        RSA_free(key);

        return ret;
}

int
main (int argc, char *argv[])
{
        FILE *fp = stdout, *fpin = NULL;
        size_t bits = 1024;
        unsigned int pubexp = DEFAULT_PUBEXP;
        extern char *optarg;
        extern int optind;
        int c, fd = -1, fdin = -1;
        char *fname = NULL, *finput = NULL;

        while ((c = getopt(argc, argv, "e:b:f:i:h")) != -1)
                switch (c) {
                        case 'e':
                                pubexp = (unsigned int)strtoul(optarg, NULL, 0);
                                break;
                        case 'b':
                                bits = atoi(optarg);
                                break;
                        case 'f':
                                fname = optarg;
                                break;
                        case 'i':
                                finput = optarg;
                                break;
                        case 'h':
                        default:
                                usage(argv[0]);
                }

        if (fname) {
                umask(0077);
                /* Restrictive access due to private key material. */
                fd = open(fname, O_WRONLY | O_CREAT | O_EXCL | O_NOFOLLOW, S_IRUSR | S_IWUSR);
                if (fd < 0) {
                        if (errno == EEXIST)
                                fprintf(stderr, "%s: file exists! Please use a different name.\n", fname);
                        else
                                fprintf(stderr, "%s: %s\n", fname, strerror(errno));
                        exit(1);
                }
                fp = fdopen(fd, "w");
                if (fp == NULL) {
                        fprintf(stderr, "%s: %s\n", fname, strerror(errno));
                        close(fd);
                        exit(1);
                }
        }

        if (finput) {
                /* Restrictive access once more. Do not be fooled by a link. */
                fdin = open(finput, O_RDONLY | O_NOFOLLOW);
                if (fdin < 0) {
                        if (errno == ELOOP)
                                fprintf(stderr, "%s: file is a link. Discarded for security.\n", fname);
                        if (fp)
                                fclose(fp);
                        exit(1);
                }
                fpin = fdopen(fdin, "r");
                if (fpin == NULL) {
                        fprintf(stderr, "%s: %s\n", fname, strerror(errno));
                        close(fdin);
                        if (fp)
                                fclose(fp);
                        exit(1);
                }

        }

        ploginit();
        eay_init();

        if (fpin)
                convert_rsa_key(fp, fpin);
        else
                gen_rsa_key(fp, bits, pubexp);

        fclose(fp);
        if (fpin)
                fclose(fpin);

        return 0;
}