/* $OpenBSD: dsa_ameth.c,v 1.37 2022/06/27 12:36:05 tb Exp $ */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project 2006.
 */
/* ====================================================================
 * Copyright (c) 2006 The OpenSSL Project.  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. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 OpenSSL PROJECT OR
 * ITS 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 product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>

#include <openssl/opensslconf.h>

#include <openssl/asn1.h>
#include <openssl/bn.h>
#include <openssl/cms.h>
#include <openssl/dsa.h>
#include <openssl/err.h>
#include <openssl/x509.h>

#include "asn1_locl.h"
#include "bn_lcl.h"
#include "dsa_locl.h"
#include "evp_locl.h"

static int
dsa_pub_decode(EVP_PKEY *pkey, X509_PUBKEY *pubkey)
{
        const unsigned char *p, *pm;
        int pklen, pmlen;
        int ptype;
        const void *pval;
        const ASN1_STRING *pstr;
        X509_ALGOR *palg;
        ASN1_INTEGER *public_key = NULL;

        DSA *dsa = NULL;

        if (!X509_PUBKEY_get0_param(NULL, &p, &pklen, &palg, pubkey))
                return 0;
        X509_ALGOR_get0(NULL, &ptype, &pval, palg);

        if (ptype == V_ASN1_SEQUENCE) {
                pstr = pval;
                pm = pstr->data;
                pmlen = pstr->length;

                if (!(dsa = d2i_DSAparams(NULL, &pm, pmlen))) {
                        DSAerror(DSA_R_DECODE_ERROR);
                        goto err;
                }
        } else if (ptype == V_ASN1_NULL || ptype == V_ASN1_UNDEF) {
                if (!(dsa = DSA_new())) {
                        DSAerror(ERR_R_MALLOC_FAILURE);
                        goto err;
                }
        } else {
                DSAerror(DSA_R_PARAMETER_ENCODING_ERROR);
                goto err;
        }

        if (!(public_key = d2i_ASN1_INTEGER(NULL, &p, pklen))) {
                DSAerror(DSA_R_DECODE_ERROR);
                goto err;
        }

        if (!(dsa->pub_key = ASN1_INTEGER_to_BN(public_key, NULL))) {
                DSAerror(DSA_R_BN_DECODE_ERROR);
                goto err;
        }

        ASN1_INTEGER_free(public_key);
        EVP_PKEY_assign_DSA(pkey, dsa);
        return 1;

err:
        if (public_key)
                ASN1_INTEGER_free(public_key);
        DSA_free(dsa);
        return 0;
}

static int
dsa_pub_encode(X509_PUBKEY *pk, const EVP_PKEY *pkey)
{
        DSA *dsa;
        ASN1_INTEGER *pubint = NULL;
        ASN1_STRING *str = NULL;
        int ptype = V_ASN1_UNDEF;
        unsigned char *penc = NULL;
        int penclen;

        dsa = pkey->pkey.dsa;
        if (pkey->save_parameters && dsa->p && dsa->q && dsa->g) {
                if ((str = ASN1_STRING_new()) == NULL) {
                        DSAerror(ERR_R_MALLOC_FAILURE);
                        goto err;
                }
                str->length = i2d_DSAparams(dsa, &str->data);
                if (str->length <= 0) {
                        DSAerror(ERR_R_MALLOC_FAILURE);
                        goto err;
                }
                ptype = V_ASN1_SEQUENCE;
        }

        if ((pubint = BN_to_ASN1_INTEGER(dsa->pub_key, NULL)) == NULL) {
                DSAerror(ERR_R_MALLOC_FAILURE);
                goto err;
        }

        penclen = i2d_ASN1_INTEGER(pubint, &penc);
        ASN1_INTEGER_free(pubint);

        if (penclen <= 0) {
                DSAerror(ERR_R_MALLOC_FAILURE);
                goto err;
        }

        if (X509_PUBKEY_set0_param(pk, OBJ_nid2obj(EVP_PKEY_DSA), ptype, str,
            penc, penclen))
                return 1;

 err:
        free(penc);
        ASN1_STRING_free(str);

        return 0;
}

/* In PKCS#8 DSA: you just get a private key integer and parameters in the
 * AlgorithmIdentifier the pubkey must be recalculated.
 */
static int
dsa_priv_decode(EVP_PKEY *pkey, const PKCS8_PRIV_KEY_INFO *p8)
{
        const unsigned char *p, *pm;
        int pklen, pmlen;
        int ptype;
        const void *pval;
        const ASN1_STRING *pstr;
        const X509_ALGOR *palg;
        ASN1_INTEGER *privkey = NULL;
        BN_CTX *ctx = NULL;
        DSA *dsa = NULL;

        int ret = 0;

        if (!PKCS8_pkey_get0(NULL, &p, &pklen, &palg, p8))
                return 0;
        X509_ALGOR_get0(NULL, &ptype, &pval, palg);
        if (ptype != V_ASN1_SEQUENCE)
                goto decerr;

        if ((privkey = d2i_ASN1_INTEGER(NULL, &p, pklen)) == NULL)
                goto decerr;
        if (privkey->type == V_ASN1_NEG_INTEGER)
                goto decerr;

        pstr = pval;
        pm = pstr->data;
        pmlen = pstr->length;
        if (!(dsa = d2i_DSAparams(NULL, &pm, pmlen)))
                goto decerr;
        /* We have parameters now set private key */
        if (!(dsa->priv_key = ASN1_INTEGER_to_BN(privkey, NULL))) {
                DSAerror(DSA_R_BN_ERROR);
                goto dsaerr;
        }
        /* Calculate public key */
        if (!(dsa->pub_key = BN_new())) {
                DSAerror(ERR_R_MALLOC_FAILURE);
                goto dsaerr;
        }
        if (!(ctx = BN_CTX_new())) {
                DSAerror(ERR_R_MALLOC_FAILURE);
                goto dsaerr;
        }

        if (!BN_mod_exp_ct(dsa->pub_key, dsa->g, dsa->priv_key, dsa->p, ctx)) {
                DSAerror(DSA_R_BN_ERROR);
                goto dsaerr;
        }

        if (!EVP_PKEY_assign_DSA(pkey, dsa))
                goto decerr;

        ret = 1;
        goto done;

decerr:
        DSAerror(DSA_R_DECODE_ERROR);
dsaerr:
        DSA_free(dsa);
done:
        BN_CTX_free(ctx);
        ASN1_INTEGER_free(privkey);
        return ret;
}

static int
dsa_priv_encode(PKCS8_PRIV_KEY_INFO *p8, const EVP_PKEY *pkey)
{
        ASN1_STRING *params = NULL;
        ASN1_INTEGER *prkey = NULL;
        unsigned char *dp = NULL;
        int dplen;

        params = ASN1_STRING_new();
        if (!params) {
                DSAerror(ERR_R_MALLOC_FAILURE);
                goto err;
        }

        params->length = i2d_DSAparams(pkey->pkey.dsa, &params->data);
        if (params->length <= 0) {
                DSAerror(ERR_R_MALLOC_FAILURE);
                goto err;
        }
        params->type = V_ASN1_SEQUENCE;

        /* Get private key into integer */
        prkey = BN_to_ASN1_INTEGER(pkey->pkey.dsa->priv_key, NULL);
        if (!prkey) {
                DSAerror(DSA_R_BN_ERROR);
                goto err;
        }

        dplen = i2d_ASN1_INTEGER(prkey, &dp);

        ASN1_INTEGER_free(prkey);
        prkey = NULL;

        if (!PKCS8_pkey_set0(p8, OBJ_nid2obj(NID_dsa), 0, V_ASN1_SEQUENCE,
            params, dp, dplen))
                goto err;

        return 1;

err:
        free(dp);
        ASN1_STRING_free(params);
        ASN1_INTEGER_free(prkey);
        return 0;
}

static int
int_dsa_size(const EVP_PKEY *pkey)
{
        return DSA_size(pkey->pkey.dsa);
}

static int
dsa_bits(const EVP_PKEY *pkey)
{
        return BN_num_bits(pkey->pkey.dsa->p);
}

static int
dsa_security_bits(const EVP_PKEY *pkey)
{
        return DSA_security_bits(pkey->pkey.dsa);
}

static int
dsa_missing_parameters(const EVP_PKEY *pkey)
{
        DSA *dsa;

        dsa = pkey->pkey.dsa;
        if (dsa->p == NULL || dsa->q == NULL || dsa->g == NULL)
                return 1;
        return 0;
}

static int
dsa_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from)
{
        BIGNUM *a;

        if ((a = BN_dup(from->pkey.dsa->p)) == NULL)
                return 0;
        BN_free(to->pkey.dsa->p);
        to->pkey.dsa->p = a;

        if ((a = BN_dup(from->pkey.dsa->q)) == NULL)
                return 0;
        BN_free(to->pkey.dsa->q);
        to->pkey.dsa->q = a;

        if ((a = BN_dup(from->pkey.dsa->g)) == NULL)
                return 0;
        BN_free(to->pkey.dsa->g);
        to->pkey.dsa->g = a;
        return 1;
}

static int
dsa_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b)
{
        if (BN_cmp(a->pkey.dsa->p, b->pkey.dsa->p) ||
            BN_cmp(a->pkey.dsa->q, b->pkey.dsa->q) ||
            BN_cmp(a->pkey.dsa->g, b->pkey.dsa->g))
                return 0;
        else
                return 1;
}

static int
dsa_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
{
        if (BN_cmp(b->pkey.dsa->pub_key, a->pkey.dsa->pub_key) != 0)
                return 0;
        else
                return 1;
}

static void
int_dsa_free(EVP_PKEY *pkey)
{
        DSA_free(pkey->pkey.dsa);
}

static void
update_buflen(const BIGNUM *b, size_t *pbuflen)
{
        size_t i;

        if (!b)
                return;
        if (*pbuflen < (i = (size_t)BN_num_bytes(b)))
                *pbuflen = i;
}

static int
do_dsa_print(BIO *bp, const DSA *x, int off, int ptype)
{
        unsigned char *m = NULL;
        int ret = 0;
        size_t buf_len = 0;
        const char *ktype = NULL;
        const BIGNUM *priv_key, *pub_key;

        if (ptype == 2)
                priv_key = x->priv_key;
        else
                priv_key = NULL;

        if (ptype > 0)
                pub_key = x->pub_key;
        else
                pub_key = NULL;

        if (ptype == 2)
                ktype = "Private-Key";
        else if (ptype == 1)
                ktype = "Public-Key";
        else
                ktype = "DSA-Parameters";

        update_buflen(x->p, &buf_len);
        update_buflen(x->q, &buf_len);
        update_buflen(x->g, &buf_len);
        update_buflen(priv_key, &buf_len);
        update_buflen(pub_key, &buf_len);

        m = malloc(buf_len + 10);
        if (m == NULL) {
                DSAerror(ERR_R_MALLOC_FAILURE);
                goto err;
        }

        if (priv_key) {
                if (!BIO_indent(bp, off, 128))
                        goto err;
                if (BIO_printf(bp, "%s: (%d bit)\n", ktype,
                    BN_num_bits(x->p)) <= 0)
                        goto err;
        }

        if (!ASN1_bn_print(bp, "priv:", priv_key, m, off))
                goto err;
        if (!ASN1_bn_print(bp, "pub: ", pub_key, m, off))
                goto err;
        if (!ASN1_bn_print(bp, "P:   ", x->p, m, off))
                goto err;
        if (!ASN1_bn_print(bp, "Q:   ", x->q, m, off))
                goto err;
        if (!ASN1_bn_print(bp, "G:   ", x->g, m, off))
                goto err;
        ret = 1;
err:
        free(m);
        return ret;
}

static int
dsa_param_decode(EVP_PKEY *pkey, const unsigned char **pder, int derlen)
{
        DSA *dsa;

        if (!(dsa = d2i_DSAparams(NULL, pder, derlen))) {
                DSAerror(ERR_R_DSA_LIB);
                return 0;
        }
        EVP_PKEY_assign_DSA(pkey, dsa);
        return 1;
}

static int
dsa_param_encode(const EVP_PKEY *pkey, unsigned char **pder)
{
        return i2d_DSAparams(pkey->pkey.dsa, pder);
}

static int
dsa_param_print(BIO *bp, const EVP_PKEY *pkey, int indent, ASN1_PCTX *ctx)
{
        return do_dsa_print(bp, pkey->pkey.dsa, indent, 0);
}

static int
dsa_pub_print(BIO *bp, const EVP_PKEY *pkey, int indent, ASN1_PCTX *ctx)
{
        return do_dsa_print(bp, pkey->pkey.dsa, indent, 1);
}

static int
dsa_priv_print(BIO *bp, const EVP_PKEY *pkey, int indent, ASN1_PCTX *ctx)
{
        return do_dsa_print(bp, pkey->pkey.dsa, indent, 2);
}

static int
old_dsa_priv_decode(EVP_PKEY *pkey, const unsigned char **pder, int derlen)
{
        DSA *dsa;
        BN_CTX *ctx = NULL;
        BIGNUM *j, *p1, *newp1, *powg;
        int qbits;

        if (!(dsa = d2i_DSAPrivateKey(NULL, pder, derlen))) {
                DSAerror(ERR_R_DSA_LIB);
                return 0;
        }

        /* FIPS 186-3 allows only three different sizes for q. */
        qbits = BN_num_bits(dsa->q);
        if (qbits != 160 && qbits != 224 && qbits != 256) {
                DSAerror(DSA_R_BAD_Q_VALUE);
                goto err;
        }
        if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
                DSAerror(DSA_R_MODULUS_TOO_LARGE);
                goto err;
        }

        /* Check that 1 < g < p. */
        if (BN_cmp(dsa->g, BN_value_one()) <= 0 ||
            BN_cmp(dsa->g, dsa->p) >= 0) {
                DSAerror(DSA_R_PARAMETER_ENCODING_ERROR); /* XXX */
                goto err;
        }

        ctx = BN_CTX_new();
        if (ctx == NULL)
                goto err;

        /*
         * Check that p and q are consistent with each other.
         */

        j = BN_CTX_get(ctx);
        p1 = BN_CTX_get(ctx);
        newp1 = BN_CTX_get(ctx);
        powg = BN_CTX_get(ctx);
        if (j == NULL || p1 == NULL || newp1 == NULL || powg == NULL)
                goto err;
        /* p1 = p - 1 */
        if (BN_sub(p1, dsa->p, BN_value_one()) == 0)
                goto err;
        /* j = (p - 1) / q */
        if (BN_div_ct(j, NULL, p1, dsa->q, ctx) == 0)
                goto err;
        /* q * j should == p - 1 */
        if (BN_mul(newp1, dsa->q, j, ctx) == 0)
                goto err;
        if (BN_cmp(newp1, p1) != 0) {
                DSAerror(DSA_R_BAD_Q_VALUE);
                goto err;
        }

        /*
         * Check that g generates a multiplicative subgroup of order q.
         * We only check that g^q == 1, so the order is a divisor of q.
         * Once we know that q is prime, this is enough.
         */

        if (!BN_mod_exp_ct(powg, dsa->g, dsa->q, dsa->p, ctx))
                goto err;
        if (BN_cmp(powg, BN_value_one()) != 0) {
                DSAerror(DSA_R_PARAMETER_ENCODING_ERROR); /* XXX */
                goto err;
        }

        /*
         * Check that q is not a composite number.
         */

        if (BN_is_prime_ex(dsa->q, BN_prime_checks, ctx, NULL) <= 0) {
                DSAerror(DSA_R_BAD_Q_VALUE);
                goto err;
        }

        BN_CTX_free(ctx);

        EVP_PKEY_assign_DSA(pkey, dsa);
        return 1;

 err:
        BN_CTX_free(ctx);
        DSA_free(dsa);
        return 0;
}

static int
old_dsa_priv_encode(const EVP_PKEY *pkey, unsigned char **pder)
{
        return i2d_DSAPrivateKey(pkey->pkey.dsa, pder);
}

static int
dsa_sig_print(BIO *bp, const X509_ALGOR *sigalg, const ASN1_STRING *sig,
    int indent, ASN1_PCTX *pctx)
{
        DSA_SIG *dsa_sig;
        const unsigned char *p;

        if (!sig) {
                if (BIO_puts(bp, "\n") <= 0)
                        return 0;
                else
                        return 1;
        }
        p = sig->data;
        dsa_sig = d2i_DSA_SIG(NULL, &p, sig->length);
        if (dsa_sig) {
                int rv = 0;
                size_t buf_len = 0;
                unsigned char *m = NULL;

                update_buflen(dsa_sig->r, &buf_len);
                update_buflen(dsa_sig->s, &buf_len);
                m = malloc(buf_len + 10);
                if (m == NULL) {
                        DSAerror(ERR_R_MALLOC_FAILURE);
                        goto err;
                }

                if (BIO_write(bp, "\n", 1) != 1)
                        goto err;

                if (!ASN1_bn_print(bp, "r:   ", dsa_sig->r, m, indent))
                        goto err;
                if (!ASN1_bn_print(bp, "s:   ", dsa_sig->s, m, indent))
                        goto err;
                rv = 1;
err:
                free(m);
                DSA_SIG_free(dsa_sig);
                return rv;
        }
        return X509_signature_dump(bp, sig, indent);
}

static int
dsa_pkey_ctrl(EVP_PKEY *pkey, int op, long arg1, void *arg2)
{
        switch (op) {
        case ASN1_PKEY_CTRL_PKCS7_SIGN:
                if (arg1 == 0) {
                        int snid, hnid;
                        X509_ALGOR *alg1, *alg2;

                        PKCS7_SIGNER_INFO_get0_algs(arg2, NULL, &alg1, &alg2);
                        if (alg1 == NULL || alg1->algorithm == NULL)
                                return -1;
                        hnid = OBJ_obj2nid(alg1->algorithm);
                        if (hnid == NID_undef)
                                return -1;
                        if (!OBJ_find_sigid_by_algs(&snid, hnid,
                            EVP_PKEY_id(pkey)))
                                return -1;
                        X509_ALGOR_set0(alg2, OBJ_nid2obj(snid), V_ASN1_UNDEF,
                            0);
                }
                return 1;

#ifndef OPENSSL_NO_CMS
        case ASN1_PKEY_CTRL_CMS_SIGN:
                if (arg1 == 0) {
                        int snid, hnid;
                        X509_ALGOR *alg1, *alg2;

                        CMS_SignerInfo_get0_algs(arg2, NULL, NULL, &alg1, &alg2);
                        if (alg1 == NULL || alg1->algorithm == NULL)
                                return -1;
                        hnid = OBJ_obj2nid(alg1->algorithm);
                        if (hnid == NID_undef)
                                return -1;
                        if (!OBJ_find_sigid_by_algs(&snid, hnid, EVP_PKEY_id(pkey)))
                                return -1;
                        X509_ALGOR_set0(alg2, OBJ_nid2obj(snid), V_ASN1_UNDEF, 0);
                }
                return 1;

        case ASN1_PKEY_CTRL_CMS_RI_TYPE:
                *(int *)arg2 = CMS_RECIPINFO_NONE;
                return 1;
#endif

        case ASN1_PKEY_CTRL_DEFAULT_MD_NID:
                *(int *)arg2 = NID_sha1;
                return 2;

        default:
                return -2;
        }
}

/* NB these are sorted in pkey_id order, lowest first */

const EVP_PKEY_ASN1_METHOD dsa_asn1_meths[] = {
        {
                .pkey_id = EVP_PKEY_DSA2,
                .pkey_base_id = EVP_PKEY_DSA,
                .pkey_flags = ASN1_PKEY_ALIAS
        },

        {
                .pkey_id = EVP_PKEY_DSA1,
                .pkey_base_id = EVP_PKEY_DSA,
                .pkey_flags = ASN1_PKEY_ALIAS
        },

        {
                .pkey_id = EVP_PKEY_DSA4,
                .pkey_base_id = EVP_PKEY_DSA,
                .pkey_flags = ASN1_PKEY_ALIAS
        },

        {
                .pkey_id = EVP_PKEY_DSA3,
                .pkey_base_id = EVP_PKEY_DSA,
                .pkey_flags = ASN1_PKEY_ALIAS
        },

        {
                .pkey_id = EVP_PKEY_DSA,
                .pkey_base_id = EVP_PKEY_DSA,

                .pem_str = "DSA",
                .info = "OpenSSL DSA method",

                .pub_decode = dsa_pub_decode,
                .pub_encode = dsa_pub_encode,
                .pub_cmp = dsa_pub_cmp,
                .pub_print = dsa_pub_print,

                .priv_decode = dsa_priv_decode,
                .priv_encode = dsa_priv_encode,
                .priv_print = dsa_priv_print,

                .pkey_size = int_dsa_size,
                .pkey_bits = dsa_bits,
                .pkey_security_bits = dsa_security_bits,

                .param_decode = dsa_param_decode,
                .param_encode = dsa_param_encode,
                .param_missing = dsa_missing_parameters,
                .param_copy = dsa_copy_parameters,
                .param_cmp = dsa_cmp_parameters,
                .param_print = dsa_param_print,
                .sig_print = dsa_sig_print,

                .pkey_free = int_dsa_free,
                .pkey_ctrl = dsa_pkey_ctrl,
                .old_priv_decode = old_dsa_priv_decode,
                .old_priv_encode = old_dsa_priv_encode
        }
};