| /* 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 <schoch@sheba.arc.nasa.gov>. */ |
| |
| #include <openssl/dsa.h> |
| |
| #include <string.h> |
| |
| #include <openssl/bn.h> |
| #include <openssl/dh.h> |
| #include <openssl/digest.h> |
| #include <openssl/engine.h> |
| #include <openssl/err.h> |
| #include <openssl/ex_data.h> |
| #include <openssl/mem.h> |
| #include <openssl/rand.h> |
| #include <openssl/sha.h> |
| #include <openssl/thread.h> |
| |
| #include "internal.h" |
| #include "../fipsmodule/bn/internal.h" |
| #include "../internal.h" |
| |
| |
| // Primality test according to FIPS PUB 186[-1], Appendix 2.1: 50 rounds of |
| // Miller-Rabin. |
| #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; |
| } |
| |
| unsigned DSA_bits(const DSA *dsa) { return BN_num_bits(dsa->p); } |
| |
| const BIGNUM *DSA_get0_pub_key(const DSA *dsa) { return dsa->pub_key; } |
| |
| const BIGNUM *DSA_get0_priv_key(const DSA *dsa) { return dsa->priv_key; } |
| |
| const BIGNUM *DSA_get0_p(const DSA *dsa) { return dsa->p; } |
| |
| const BIGNUM *DSA_get0_q(const DSA *dsa) { return dsa->q; } |
| |
| const BIGNUM *DSA_get0_g(const DSA *dsa) { return dsa->g; } |
| |
| 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, BN_GENCB_GENERATED, 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, BN_GENCB_GENERATED, 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); |
| } |
| |
| void DSA_SIG_get0(const DSA_SIG *sig, const BIGNUM **out_r, |
| const BIGNUM **out_s) { |
| if (out_r != NULL) { |
| *out_r = sig->r; |
| } |
| if (out_s != NULL) { |
| *out_s = sig->s; |
| } |
| } |
| |
| int DSA_SIG_set0(DSA_SIG *sig, BIGNUM *r, BIGNUM *s) { |
| if (r == NULL || s == NULL) { |
| return 0; |
| } |
| BN_free(sig->r); |
| BN_free(sig->s); |
| sig->r = r; |
| sig->s = s; |
| return 1; |
| } |
| |
| // 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_check_parameters(dsa)) { |
| 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) { |
| *out_valid = 0; |
| if (!dsa_check_parameters(dsa)) { |
| return 0; |
| } |
| |
| int ret = 0; |
| BIGNUM u1, u2, t1; |
| BN_init(&u1); |
| BN_init(&u2); |
| BN_init(&t1); |
| BN_CTX *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 |
| unsigned q_bits = BN_num_bits(dsa->q); |
| if (digest_len > (q_bits >> 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 = (q_bits >> 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; |
| } |