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- /* 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/digest.h>
- #include <openssl/err.h>
- #include <openssl/rand.h>
- #include <openssl/sha.h>
- #include <openssl/thread.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 sign_setup(const DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
- BIGNUM **rp, const uint8_t *digest, size_t digest_len) {
- BN_CTX *ctx;
- BIGNUM k, kq, *K, *kinv = NULL, *r = NULL;
- int ret = 0;
-
- if (!dsa->p || !dsa->q || !dsa->g) {
- OPENSSL_PUT_ERROR(DSA, DSA_R_MISSING_PARAMETERS);
- return 0;
- }
-
- BN_init(&k);
- BN_init(&kq);
-
- ctx = ctx_in;
- if (ctx == NULL) {
- ctx = BN_CTX_new();
- if (ctx == NULL) {
- goto err;
- }
- }
-
- r = BN_new();
- if (r == NULL) {
- goto err;
- }
-
- /* Get random k */
- do {
- /* If possible, we'll include the private key and message digest in the k
- * generation. The |digest| argument is only empty if |DSA_sign_setup| is
- * being used. */
- int ok;
-
- if (digest_len > 0) {
- ok = BN_generate_dsa_nonce(&k, dsa->q, dsa->priv_key, digest, digest_len,
- ctx);
- } else {
- ok = BN_rand_range(&k, dsa->q);
- }
- if (!ok) {
- goto err;
- }
- } while (BN_is_zero(&k));
-
- BN_set_flags(&k, BN_FLG_CONSTTIME);
-
- if (BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p,
- (CRYPTO_MUTEX *)&dsa->method_mont_p_lock, dsa->p,
- ctx) == NULL) {
- goto err;
- }
-
- /* Compute r = (g^k mod p) mod q */
- if (!BN_copy(&kq, &k)) {
- goto err;
- }
-
- /* We do not want timing information to leak the length of k,
- * so we compute g^k using an equivalent exponent of fixed length.
- *
- * (This is a kludge that we need because the BN_mod_exp_mont()
- * does not let us specify the desired timing behaviour.) */
-
- if (!BN_add(&kq, &kq, dsa->q)) {
- goto err;
- }
- if (BN_num_bits(&kq) <= BN_num_bits(dsa->q) && !BN_add(&kq, &kq, dsa->q)) {
- goto err;
- }
-
- K = &kq;
-
- if (!BN_mod_exp_mont(r, dsa->g, K, dsa->p, ctx, dsa->method_mont_p)) {
- goto err;
- }
- if (!BN_mod(r, r, dsa->q, ctx)) {
- goto err;
- }
-
- /* Compute part of 's = inv(k) (m + xr) mod q' */
- kinv = BN_mod_inverse(NULL, &k, dsa->q, ctx);
- if (kinv == NULL) {
- goto err;
- }
-
- BN_clear_free(*kinvp);
- *kinvp = kinv;
- kinv = NULL;
- BN_clear_free(*rp);
- *rp = r;
- ret = 1;
-
- err:
- if (!ret) {
- OPENSSL_PUT_ERROR(DSA, ERR_R_BN_LIB);
- if (r != NULL) {
- BN_clear_free(r);
- }
- }
-
- if (ctx_in == NULL) {
- BN_CTX_free(ctx);
- }
- BN_clear_free(&k);
- BN_clear_free(&kq);
- return ret;
- }
-
- static DSA_SIG *sign(const uint8_t *digest, size_t digest_len, DSA *dsa) {
- BIGNUM *kinv = NULL, *r = NULL, *s = NULL;
- BIGNUM m;
- BIGNUM xr;
- BN_CTX *ctx = NULL;
- int reason = ERR_R_BN_LIB;
- DSA_SIG *ret = NULL;
- int noredo = 0;
-
- BN_init(&m);
- BN_init(&xr);
-
- if (!dsa->p || !dsa->q || !dsa->g) {
- reason = DSA_R_MISSING_PARAMETERS;
- goto err;
- }
-
- s = BN_new();
- if (s == NULL) {
- goto err;
- }
- ctx = BN_CTX_new();
- if (ctx == NULL) {
- goto err;
- }
-
- redo:
- if (dsa->kinv == NULL || dsa->r == NULL) {
- if (!DSA_sign_setup(dsa, ctx, &kinv, &r)) {
- goto err;
- }
- } else {
- kinv = dsa->kinv;
- dsa->kinv = NULL;
- r = dsa->r;
- dsa->r = NULL;
- noredo = 1;
- }
-
- if (digest_len > BN_num_bytes(dsa->q)) {
- /* 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 = BN_num_bytes(dsa->q);
- }
-
- if (BN_bin2bn(digest, digest_len, &m) == NULL) {
- goto err;
- }
-
- /* Compute s = inv(k) (m + xr) mod q */
- if (!BN_mod_mul(&xr, dsa->priv_key, r, dsa->q, ctx)) {
- goto err; /* s = xr */
- }
- if (!BN_add(s, &xr, &m)) {
- goto err; /* s = m + xr */
- }
- if (BN_cmp(s, dsa->q) > 0) {
- if (!BN_sub(s, s, dsa->q)) {
- goto err;
- }
- }
- if (!BN_mod_mul(s, s, kinv, dsa->q, ctx)) {
- goto err;
- }
-
- ret = DSA_SIG_new();
- if (ret == NULL) {
- 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)) {
- if (noredo) {
- reason = DSA_R_NEED_NEW_SETUP_VALUES;
- goto err;
- }
- goto redo;
- }
- ret->r = r;
- ret->s = s;
-
- err:
- if (!ret) {
- OPENSSL_PUT_ERROR(DSA, reason);
- BN_free(r);
- BN_free(s);
- }
- BN_CTX_free(ctx);
- BN_clear_free(&m);
- BN_clear_free(&xr);
- BN_clear_free(kinv);
-
- return ret;
- }
-
- static int verify(int *out_valid, const uint8_t *dgst, size_t digest_len,
- DSA_SIG *sig, const DSA *dsa) {
- BN_CTX *ctx;
- BIGNUM u1, u2, t1;
- BN_MONT_CTX *mont = NULL;
- 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(dgst, 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;
- }
-
- mont = BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p,
- (CRYPTO_MUTEX *)&dsa->method_mont_p_lock,
- dsa->p, ctx);
- if (!mont) {
- goto err;
- }
-
- if (!BN_mod_exp2_mont(&t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, ctx,
- mont)) {
- 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;
- }
-
- static int keygen(DSA *dsa) {
- int ok = 0;
- BN_CTX *ctx = NULL;
- BIGNUM *pub_key = NULL, *priv_key = NULL;
- BIGNUM prk;
-
- 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;
- }
- }
-
- do {
- if (!BN_rand_range(priv_key, dsa->q)) {
- goto err;
- }
- } while (BN_is_zero(priv_key));
-
- pub_key = dsa->pub_key;
- if (pub_key == NULL) {
- pub_key = BN_new();
- if (pub_key == NULL) {
- goto err;
- }
- }
-
- BN_init(&prk);
- BN_with_flags(&prk, priv_key, BN_FLG_CONSTTIME);
-
- if (!BN_mod_exp(pub_key, dsa->g, &prk, dsa->p, ctx)) {
- 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;
- }
-
- static int paramgen(DSA *ret, unsigned bits, const uint8_t *seed_in,
- size_t seed_len, int *counter_ret, unsigned long *h_ret,
- 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 qbits, qsize;
- const EVP_MD *evpmd;
-
- if (bits >= 2048) {
- qbits = 256;
- evpmd = EVP_sha256();
- } else {
- qbits = 160;
- evpmd = EVP_sha1();
- }
- qsize = qbits / 8;
-
- if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
- qsize != SHA256_DIGEST_LENGTH) {
- /* invalid q size */
- return 0;
- }
-
- if (bits < 512) {
- bits = 512;
- }
-
- bits = (bits + 63) / 64 * 64;
-
- /* NB: seed_len == 0 is special case: copy generated seed to
- * seed_in if it is not NULL. */
- if (seed_len && (seed_len < (size_t)qsize)) {
- seed_in = NULL; /* seed buffer too small -- ignore */
- }
- if (seed_len > (size_t)qsize) {
- seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger SEED,
- * but our internal buffers are restricted to 160 bits*/
- }
- if (seed_in != NULL) {
- memcpy(seed, seed_in, seed_len);
- }
-
- ctx = BN_CTX_new();
- if (ctx == NULL) {
- goto err;
- }
- BN_CTX_start(ctx);
-
- mont = BN_MONT_CTX_new();
- if (mont == NULL) {
- goto err;
- }
-
- 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 (;;) {
- int seed_is_random;
-
- /* step 1 */
- if (!BN_GENCB_call(cb, 0, m++)) {
- goto err;
- }
-
- if (!seed_len) {
- if (!RAND_bytes(seed, qsize)) {
- goto err;
- }
- seed_is_random = 1;
- } else {
- seed_is_random = 0;
- seed_len = 0; /* use random seed if 'seed_in' turns out to be bad*/
- }
- memcpy(buf, seed, qsize);
- 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, seed_is_random, 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;
- }
-
- if (!BN_set_word(test, h) ||
- !BN_MONT_CTX_set(mont, p, ctx)) {
- 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(ret->p);
- BN_free(ret->q);
- BN_free(ret->g);
- ret->p = BN_dup(p);
- ret->q = BN_dup(q);
- ret->g = BN_dup(g);
- if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
- ok = 0;
- goto err;
- }
- if (counter_ret != NULL) {
- *counter_ret = counter;
- }
- if (h_ret != NULL) {
- *h_ret = h;
- }
- }
-
- if (ctx) {
- BN_CTX_end(ctx);
- BN_CTX_free(ctx);
- }
-
- BN_MONT_CTX_free(mont);
-
- return ok;
- }
-
- static int finish(DSA *dsa) {
- BN_MONT_CTX_free(dsa->method_mont_p);
- dsa->method_mont_p = NULL;
- return 1;
- }
-
- const struct dsa_method DSA_default_method = {
- {
- 0 /* references */,
- 1 /* is_static */,
- },
- NULL /* app_data */,
-
- NULL /* init */,
- finish /* finish */,
-
- sign,
- sign_setup,
- verify,
-
- paramgen,
- keygen,
- };
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