/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) * All rights reserved. * * This package is an SSL implementation written * by Eric Young (eay@cryptsoft.com). * The implementation was written so as to conform with Netscapes SSL. * * This library is free for commercial and non-commercial use as long as * the following conditions are aheared to. The following conditions * apply to all code found in this distribution, be it the RC4, RSA, * lhash, DES, etc., code; not just the SSL code. The SSL documentation * included with this distribution is covered by the same copyright terms * except that the holder is Tim Hudson (tjh@cryptsoft.com). * * Copyright remains Eric Young's, and as such any Copyright notices in * the code are not to be removed. * If this package is used in a product, Eric Young should be given attribution * as the author of the parts of the library used. * This can be in the form of a textual message at program startup or * in documentation (online or textual) provided with the package. * * 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 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 acknowledgement: * "This product includes cryptographic software written by * Eric Young (eay@cryptsoft.com)" * The word 'cryptographic' can be left out if the rouines from the library * being used are not cryptographic related :-). * 4. If you include any Windows specific code (or a derivative thereof) from * the apps directory (application code) you must include an acknowledgement: * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" * * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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 AUTHOR 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. * * The licence and distribution terms for any publically available version or * derivative of this code cannot be changed. i.e. this code cannot simply be * copied and put under another distribution licence * [including the GNU Public Licence.] * * The DSS routines are based on patches supplied by * Steven Schoch . */ #include #include #include #include #include #include #include #include #include #include #include #include #include "../fipsmodule/bn/internal.h" #include "../internal.h" #define OPENSSL_DSA_MAX_MODULUS_BITS 10000 // Primality test according to FIPS PUB 186[-1], Appendix 2.1: 50 rounds of // Rabin-Miller #define DSS_prime_checks 50 static int dsa_sign_setup(const DSA *dsa, BN_CTX *ctx_in, BIGNUM **out_kinv, BIGNUM **out_r); static CRYPTO_EX_DATA_CLASS g_ex_data_class = CRYPTO_EX_DATA_CLASS_INIT; DSA *DSA_new(void) { DSA *dsa = OPENSSL_malloc(sizeof(DSA)); if (dsa == NULL) { OPENSSL_PUT_ERROR(DSA, ERR_R_MALLOC_FAILURE); return NULL; } OPENSSL_memset(dsa, 0, sizeof(DSA)); dsa->references = 1; CRYPTO_MUTEX_init(&dsa->method_mont_lock); CRYPTO_new_ex_data(&dsa->ex_data); return dsa; } void DSA_free(DSA *dsa) { if (dsa == NULL) { return; } if (!CRYPTO_refcount_dec_and_test_zero(&dsa->references)) { return; } CRYPTO_free_ex_data(&g_ex_data_class, dsa, &dsa->ex_data); BN_clear_free(dsa->p); BN_clear_free(dsa->q); BN_clear_free(dsa->g); BN_clear_free(dsa->pub_key); BN_clear_free(dsa->priv_key); BN_MONT_CTX_free(dsa->method_mont_p); BN_MONT_CTX_free(dsa->method_mont_q); CRYPTO_MUTEX_cleanup(&dsa->method_mont_lock); OPENSSL_free(dsa); } int DSA_up_ref(DSA *dsa) { CRYPTO_refcount_inc(&dsa->references); return 1; } void DSA_get0_key(const DSA *dsa, const BIGNUM **out_pub_key, const BIGNUM **out_priv_key) { if (out_pub_key != NULL) { *out_pub_key = dsa->pub_key; } if (out_priv_key != NULL) { *out_priv_key = dsa->priv_key; } } void DSA_get0_pqg(const DSA *dsa, const BIGNUM **out_p, const BIGNUM **out_q, const BIGNUM **out_g) { if (out_p != NULL) { *out_p = dsa->p; } if (out_q != NULL) { *out_q = dsa->q; } if (out_g != NULL) { *out_g = dsa->g; } } int DSA_set0_key(DSA *dsa, BIGNUM *pub_key, BIGNUM *priv_key) { if (dsa->pub_key == NULL && pub_key == NULL) { return 0; } if (pub_key != NULL) { BN_free(dsa->pub_key); dsa->pub_key = pub_key; } if (priv_key != NULL) { BN_free(dsa->priv_key); dsa->priv_key = priv_key; } return 1; } int DSA_set0_pqg(DSA *dsa, BIGNUM *p, BIGNUM *q, BIGNUM *g) { if ((dsa->p == NULL && p == NULL) || (dsa->q == NULL && q == NULL) || (dsa->g == NULL && g == NULL)) { return 0; } if (p != NULL) { BN_free(dsa->p); dsa->p = p; } if (q != NULL) { BN_free(dsa->q); dsa->q = q; } if (g != NULL) { BN_free(dsa->g); dsa->g = g; } return 1; } int DSA_generate_parameters_ex(DSA *dsa, unsigned bits, const uint8_t *seed_in, size_t seed_len, int *out_counter, unsigned long *out_h, BN_GENCB *cb) { int ok = 0; unsigned char seed[SHA256_DIGEST_LENGTH]; unsigned char md[SHA256_DIGEST_LENGTH]; unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH]; BIGNUM *r0, *W, *X, *c, *test; BIGNUM *g = NULL, *q = NULL, *p = NULL; BN_MONT_CTX *mont = NULL; int k, n = 0, m = 0; unsigned i; int counter = 0; int r = 0; BN_CTX *ctx = NULL; unsigned int h = 2; unsigned qsize; const EVP_MD *evpmd; evpmd = (bits >= 2048) ? EVP_sha256() : EVP_sha1(); qsize = EVP_MD_size(evpmd); if (bits < 512) { bits = 512; } bits = (bits + 63) / 64 * 64; if (seed_in != NULL) { if (seed_len < (size_t)qsize) { return 0; } if (seed_len > (size_t)qsize) { // Only consume as much seed as is expected. seed_len = qsize; } OPENSSL_memcpy(seed, seed_in, seed_len); } ctx = BN_CTX_new(); if (ctx == NULL) { goto err; } BN_CTX_start(ctx); r0 = BN_CTX_get(ctx); g = BN_CTX_get(ctx); W = BN_CTX_get(ctx); q = BN_CTX_get(ctx); X = BN_CTX_get(ctx); c = BN_CTX_get(ctx); p = BN_CTX_get(ctx); test = BN_CTX_get(ctx); if (test == NULL || !BN_lshift(test, BN_value_one(), bits - 1)) { goto err; } for (;;) { // Find q. for (;;) { // step 1 if (!BN_GENCB_call(cb, 0, m++)) { goto err; } int use_random_seed = (seed_in == NULL); if (use_random_seed) { if (!RAND_bytes(seed, qsize)) { goto err; } } else { // If we come back through, use random seed next time. seed_in = NULL; } OPENSSL_memcpy(buf, seed, qsize); OPENSSL_memcpy(buf2, seed, qsize); // precompute "SEED + 1" for step 7: for (i = qsize - 1; i < qsize; i--) { buf[i]++; if (buf[i] != 0) { break; } } // step 2 if (!EVP_Digest(seed, qsize, md, NULL, evpmd, NULL) || !EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL)) { goto err; } for (i = 0; i < qsize; i++) { md[i] ^= buf2[i]; } // step 3 md[0] |= 0x80; md[qsize - 1] |= 0x01; if (!BN_bin2bn(md, qsize, q)) { goto err; } // step 4 r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx, use_random_seed, cb); if (r > 0) { break; } if (r != 0) { goto err; } // do a callback call // step 5 } if (!BN_GENCB_call(cb, 2, 0) || !BN_GENCB_call(cb, 3, 0)) { goto err; } // step 6 counter = 0; // "offset = 2" n = (bits - 1) / 160; for (;;) { if ((counter != 0) && !BN_GENCB_call(cb, 0, counter)) { goto err; } // step 7 BN_zero(W); // now 'buf' contains "SEED + offset - 1" for (k = 0; k <= n; k++) { // obtain "SEED + offset + k" by incrementing: for (i = qsize - 1; i < qsize; i--) { buf[i]++; if (buf[i] != 0) { break; } } if (!EVP_Digest(buf, qsize, md, NULL, evpmd, NULL)) { goto err; } // step 8 if (!BN_bin2bn(md, qsize, r0) || !BN_lshift(r0, r0, (qsize << 3) * k) || !BN_add(W, W, r0)) { goto err; } } // more of step 8 if (!BN_mask_bits(W, bits - 1) || !BN_copy(X, W) || !BN_add(X, X, test)) { goto err; } // step 9 if (!BN_lshift1(r0, q) || !BN_mod(c, X, r0, ctx) || !BN_sub(r0, c, BN_value_one()) || !BN_sub(p, X, r0)) { goto err; } // step 10 if (BN_cmp(p, test) >= 0) { // step 11 r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb); if (r > 0) { goto end; // found it } if (r != 0) { goto err; } } // step 13 counter++; // "offset = offset + n + 1" // step 14 if (counter >= 4096) { break; } } } end: if (!BN_GENCB_call(cb, 2, 1)) { goto err; } // We now need to generate g // Set r0=(p-1)/q if (!BN_sub(test, p, BN_value_one()) || !BN_div(r0, NULL, test, q, ctx)) { goto err; } mont = BN_MONT_CTX_new_for_modulus(p, ctx); if (mont == NULL || !BN_set_word(test, h)) { goto err; } for (;;) { // g=test^r0%p if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont)) { goto err; } if (!BN_is_one(g)) { break; } if (!BN_add(test, test, BN_value_one())) { goto err; } h++; } if (!BN_GENCB_call(cb, 3, 1)) { goto err; } ok = 1; err: if (ok) { BN_free(dsa->p); BN_free(dsa->q); BN_free(dsa->g); dsa->p = BN_dup(p); dsa->q = BN_dup(q); dsa->g = BN_dup(g); if (dsa->p == NULL || dsa->q == NULL || dsa->g == NULL) { ok = 0; goto err; } if (out_counter != NULL) { *out_counter = counter; } if (out_h != NULL) { *out_h = h; } } if (ctx) { BN_CTX_end(ctx); BN_CTX_free(ctx); } BN_MONT_CTX_free(mont); return ok; } DSA *DSAparams_dup(const DSA *dsa) { DSA *ret = DSA_new(); if (ret == NULL) { return NULL; } ret->p = BN_dup(dsa->p); ret->q = BN_dup(dsa->q); ret->g = BN_dup(dsa->g); if (ret->p == NULL || ret->q == NULL || ret->g == NULL) { DSA_free(ret); return NULL; } return ret; } int DSA_generate_key(DSA *dsa) { int ok = 0; BN_CTX *ctx = NULL; BIGNUM *pub_key = NULL, *priv_key = NULL; ctx = BN_CTX_new(); if (ctx == NULL) { goto err; } priv_key = dsa->priv_key; if (priv_key == NULL) { priv_key = BN_new(); if (priv_key == NULL) { goto err; } } if (!BN_rand_range_ex(priv_key, 1, dsa->q)) { goto err; } pub_key = dsa->pub_key; if (pub_key == NULL) { pub_key = BN_new(); if (pub_key == NULL) { goto err; } } if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p, &dsa->method_mont_lock, dsa->p, ctx) || !BN_mod_exp_mont_consttime(pub_key, dsa->g, priv_key, dsa->p, ctx, dsa->method_mont_p)) { goto err; } dsa->priv_key = priv_key; dsa->pub_key = pub_key; ok = 1; err: if (dsa->pub_key == NULL) { BN_free(pub_key); } if (dsa->priv_key == NULL) { BN_free(priv_key); } BN_CTX_free(ctx); return ok; } DSA_SIG *DSA_SIG_new(void) { DSA_SIG *sig; sig = OPENSSL_malloc(sizeof(DSA_SIG)); if (!sig) { return NULL; } sig->r = NULL; sig->s = NULL; return sig; } void DSA_SIG_free(DSA_SIG *sig) { if (!sig) { return; } BN_free(sig->r); BN_free(sig->s); OPENSSL_free(sig); } // mod_mul_consttime sets |r| to |a| * |b| modulo |mont->N|, treating |a| and // |b| as secret. This function internally uses Montgomery reduction, but // neither inputs nor outputs are in Montgomery form. static int mod_mul_consttime(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BN_MONT_CTX *mont, BN_CTX *ctx) { BN_CTX_start(ctx); BIGNUM *tmp = BN_CTX_get(ctx); // |BN_mod_mul_montgomery| removes a factor of R, so we cancel it with a // single |BN_to_montgomery| which adds one factor of R. int ok = tmp != NULL && BN_to_montgomery(tmp, a, mont, ctx) && BN_mod_mul_montgomery(r, tmp, b, mont, ctx); BN_CTX_end(ctx); return ok; } DSA_SIG *DSA_do_sign(const uint8_t *digest, size_t digest_len, const DSA *dsa) { if (!dsa->p || !dsa->q || !dsa->g) { OPENSSL_PUT_ERROR(DSA, DSA_R_MISSING_PARAMETERS); return NULL; } // Reject invalid parameters. In particular, the algorithm will infinite loop // if |g| is zero. if (BN_is_zero(dsa->p) || BN_is_zero(dsa->q) || BN_is_zero(dsa->g)) { OPENSSL_PUT_ERROR(DSA, DSA_R_INVALID_PARAMETERS); return NULL; } // We only support DSA keys that are a multiple of 8 bits. (This is a weaker // check than the one in |DSA_do_check_signature|, which only allows 160-, // 224-, and 256-bit keys. if (BN_num_bits(dsa->q) % 8 != 0) { OPENSSL_PUT_ERROR(DSA, DSA_R_BAD_Q_VALUE); return NULL; } BIGNUM *kinv = NULL, *r = NULL, *s = NULL; BIGNUM m; BIGNUM xr; BN_CTX *ctx = NULL; DSA_SIG *ret = NULL; BN_init(&m); BN_init(&xr); s = BN_new(); if (s == NULL) { goto err; } ctx = BN_CTX_new(); if (ctx == NULL) { goto err; } redo: if (!dsa_sign_setup(dsa, ctx, &kinv, &r)) { goto err; } if (digest_len > BN_num_bytes(dsa->q)) { // If the digest length is greater than the size of |dsa->q| use the // BN_num_bits(dsa->q) leftmost bits of the digest, see FIPS 186-3, 4.2. // Note the above check that |dsa->q| is a multiple of 8 bits. digest_len = BN_num_bytes(dsa->q); } if (BN_bin2bn(digest, digest_len, &m) == NULL) { goto err; } // |m| is bounded by 2^(num_bits(q)), which is slightly looser than q. This // violates |bn_mod_add_consttime| and |mod_mul_consttime|'s preconditions. // (The underlying algorithms could accept looser bounds, but we reduce for // simplicity.) size_t q_width = bn_minimal_width(dsa->q); if (!bn_resize_words(&m, q_width) || !bn_resize_words(&xr, q_width)) { goto err; } bn_reduce_once_in_place(m.d, 0 /* no carry word */, dsa->q->d, xr.d /* scratch space */, q_width); // Compute s = inv(k) (m + xr) mod q. Note |dsa->method_mont_q| is // initialized by |dsa_sign_setup|. if (!mod_mul_consttime(&xr, dsa->priv_key, r, dsa->method_mont_q, ctx) || !bn_mod_add_consttime(s, &xr, &m, dsa->q, ctx) || !mod_mul_consttime(s, s, kinv, dsa->method_mont_q, ctx)) { goto err; } // Redo if r or s is zero as required by FIPS 186-3: this is // very unlikely. if (BN_is_zero(r) || BN_is_zero(s)) { goto redo; } ret = DSA_SIG_new(); if (ret == NULL) { goto err; } ret->r = r; ret->s = s; err: if (ret == NULL) { OPENSSL_PUT_ERROR(DSA, ERR_R_BN_LIB); BN_free(r); BN_free(s); } BN_CTX_free(ctx); BN_clear_free(&m); BN_clear_free(&xr); BN_clear_free(kinv); return ret; } int DSA_do_verify(const uint8_t *digest, size_t digest_len, DSA_SIG *sig, const DSA *dsa) { int valid; if (!DSA_do_check_signature(&valid, digest, digest_len, sig, dsa)) { return -1; } return valid; } int DSA_do_check_signature(int *out_valid, const uint8_t *digest, size_t digest_len, DSA_SIG *sig, const DSA *dsa) { BN_CTX *ctx; BIGNUM u1, u2, t1; int ret = 0; unsigned i; *out_valid = 0; if (!dsa->p || !dsa->q || !dsa->g) { OPENSSL_PUT_ERROR(DSA, DSA_R_MISSING_PARAMETERS); return 0; } i = BN_num_bits(dsa->q); // FIPS 186-3 allows only different sizes for q. if (i != 160 && i != 224 && i != 256) { OPENSSL_PUT_ERROR(DSA, DSA_R_BAD_Q_VALUE); return 0; } if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) { OPENSSL_PUT_ERROR(DSA, DSA_R_MODULUS_TOO_LARGE); return 0; } BN_init(&u1); BN_init(&u2); BN_init(&t1); ctx = BN_CTX_new(); if (ctx == NULL) { goto err; } if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || BN_ucmp(sig->r, dsa->q) >= 0) { ret = 1; goto err; } if (BN_is_zero(sig->s) || BN_is_negative(sig->s) || BN_ucmp(sig->s, dsa->q) >= 0) { ret = 1; goto err; } // Calculate W = inv(S) mod Q // save W in u2 if (BN_mod_inverse(&u2, sig->s, dsa->q, ctx) == NULL) { goto err; } // save M in u1 if (digest_len > (i >> 3)) { // if the digest length is greater than the size of q use the // BN_num_bits(dsa->q) leftmost bits of the digest, see // fips 186-3, 4.2 digest_len = (i >> 3); } if (BN_bin2bn(digest, digest_len, &u1) == NULL) { goto err; } // u1 = M * w mod q if (!BN_mod_mul(&u1, &u1, &u2, dsa->q, ctx)) { goto err; } // u2 = r * w mod q if (!BN_mod_mul(&u2, sig->r, &u2, dsa->q, ctx)) { goto err; } if (!BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p, (CRYPTO_MUTEX *)&dsa->method_mont_lock, dsa->p, ctx)) { goto err; } if (!BN_mod_exp2_mont(&t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx, dsa->method_mont_p)) { goto err; } // BN_copy(&u1,&t1); // let u1 = u1 mod q if (!BN_mod(&u1, &t1, dsa->q, ctx)) { goto err; } // V is now in u1. If the signature is correct, it will be // equal to R. *out_valid = BN_ucmp(&u1, sig->r) == 0; ret = 1; err: if (ret != 1) { OPENSSL_PUT_ERROR(DSA, ERR_R_BN_LIB); } BN_CTX_free(ctx); BN_free(&u1); BN_free(&u2); BN_free(&t1); return ret; } int DSA_sign(int type, const uint8_t *digest, size_t digest_len, uint8_t *out_sig, unsigned int *out_siglen, const DSA *dsa) { DSA_SIG *s; s = DSA_do_sign(digest, digest_len, dsa); if (s == NULL) { *out_siglen = 0; return 0; } *out_siglen = i2d_DSA_SIG(s, &out_sig); DSA_SIG_free(s); return 1; } int DSA_verify(int type, const uint8_t *digest, size_t digest_len, const uint8_t *sig, size_t sig_len, const DSA *dsa) { int valid; if (!DSA_check_signature(&valid, digest, digest_len, sig, sig_len, dsa)) { return -1; } return valid; } int DSA_check_signature(int *out_valid, const uint8_t *digest, size_t digest_len, const uint8_t *sig, size_t sig_len, const DSA *dsa) { DSA_SIG *s = NULL; int ret = 0; uint8_t *der = NULL; s = DSA_SIG_new(); if (s == NULL) { goto err; } const uint8_t *sigp = sig; if (d2i_DSA_SIG(&s, &sigp, sig_len) == NULL || sigp != sig + sig_len) { goto err; } // Ensure that the signature uses DER and doesn't have trailing garbage. int der_len = i2d_DSA_SIG(s, &der); if (der_len < 0 || (size_t)der_len != sig_len || OPENSSL_memcmp(sig, der, sig_len)) { goto err; } ret = DSA_do_check_signature(out_valid, digest, digest_len, s, dsa); err: OPENSSL_free(der); DSA_SIG_free(s); return ret; } // der_len_len returns the number of bytes needed to represent a length of |len| // in DER. static size_t der_len_len(size_t len) { if (len < 0x80) { return 1; } size_t ret = 1; while (len > 0) { ret++; len >>= 8; } return ret; } int DSA_size(const DSA *dsa) { size_t order_len = BN_num_bytes(dsa->q); // Compute the maximum length of an |order_len| byte integer. Defensively // assume that the leading 0x00 is included. size_t integer_len = 1 /* tag */ + der_len_len(order_len + 1) + 1 + order_len; if (integer_len < order_len) { return 0; } // A DSA signature is two INTEGERs. size_t value_len = 2 * integer_len; if (value_len < integer_len) { return 0; } // Add the header. size_t ret = 1 /* tag */ + der_len_len(value_len) + value_len; if (ret < value_len) { return 0; } return ret; } static int dsa_sign_setup(const DSA *dsa, BN_CTX *ctx, BIGNUM **out_kinv, BIGNUM **out_r) { if (!dsa->p || !dsa->q || !dsa->g) { OPENSSL_PUT_ERROR(DSA, DSA_R_MISSING_PARAMETERS); return 0; } int ret = 0; BIGNUM k; BN_init(&k); BIGNUM *r = BN_new(); BIGNUM *kinv = BN_new(); if (r == NULL || kinv == NULL || // Get random k !BN_rand_range_ex(&k, 1, dsa->q) || !BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p, (CRYPTO_MUTEX *)&dsa->method_mont_lock, dsa->p, ctx) || !BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_q, (CRYPTO_MUTEX *)&dsa->method_mont_lock, dsa->q, ctx) || // Compute r = (g^k mod p) mod q !BN_mod_exp_mont_consttime(r, dsa->g, &k, dsa->p, ctx, dsa->method_mont_p) || // Note |BN_mod| below is not constant-time and may leak information about // |r|. |dsa->p| may be significantly larger than |dsa->q|, so this is not // easily performed in constant-time with Montgomery reduction. // // However, |r| at this point is g^k (mod p). It is almost the value of // |r| revealed in the signature anyway (g^k (mod p) (mod q)), going from // it to |k| would require computing a discrete log. !BN_mod(r, r, dsa->q, ctx) || // Compute part of 's = inv(k) (m + xr) mod q' using Fermat's Little // Theorem. !bn_mod_inverse_prime(kinv, &k, dsa->q, ctx, dsa->method_mont_q)) { OPENSSL_PUT_ERROR(DSA, ERR_R_BN_LIB); goto err; } BN_clear_free(*out_kinv); *out_kinv = kinv; kinv = NULL; BN_clear_free(*out_r); *out_r = r; r = NULL; ret = 1; err: BN_clear_free(&k); BN_clear_free(r); BN_clear_free(kinv); return ret; } int DSA_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused, CRYPTO_EX_dup *dup_unused, CRYPTO_EX_free *free_func) { int index; if (!CRYPTO_get_ex_new_index(&g_ex_data_class, &index, argl, argp, free_func)) { return -1; } return index; } int DSA_set_ex_data(DSA *dsa, int idx, void *arg) { return CRYPTO_set_ex_data(&dsa->ex_data, idx, arg); } void *DSA_get_ex_data(const DSA *dsa, int idx) { return CRYPTO_get_ex_data(&dsa->ex_data, idx); } DH *DSA_dup_DH(const DSA *dsa) { if (dsa == NULL) { return NULL; } DH *ret = DH_new(); if (ret == NULL) { goto err; } if (dsa->q != NULL) { ret->priv_length = BN_num_bits(dsa->q); if ((ret->q = BN_dup(dsa->q)) == NULL) { goto err; } } if ((dsa->p != NULL && (ret->p = BN_dup(dsa->p)) == NULL) || (dsa->g != NULL && (ret->g = BN_dup(dsa->g)) == NULL) || (dsa->pub_key != NULL && (ret->pub_key = BN_dup(dsa->pub_key)) == NULL) || (dsa->priv_key != NULL && (ret->priv_key = BN_dup(dsa->priv_key)) == NULL)) { goto err; } return ret; err: DH_free(ret); return NULL; }