diff options
Diffstat (limited to 'src/crypto/dsa/dsa_impl.c')
-rw-r--r-- | src/crypto/dsa/dsa_impl.c | 762 |
1 files changed, 762 insertions, 0 deletions
diff --git a/src/crypto/dsa/dsa_impl.c b/src/crypto/dsa/dsa_impl.c new file mode 100644 index 0000000..6719758 --- /dev/null +++ b/src/crypto/dsa/dsa_impl.c @@ -0,0 +1,762 @@ +/* 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 "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, sign_setup, 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_LOCK_DSA, dsa->p, ctx)) { + 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)) { + if (!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; + } + + if (*kinvp != NULL) { + BN_clear_free(*kinvp); + } + *kinvp = kinv; + kinv = NULL; + if (*rp != NULL) { + BN_clear_free(*rp); + } + *rp = r; + ret = 1; + +err: + if (!ret) { + OPENSSL_PUT_ERROR(DSA, sign_setup, 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, sign, reason); + BN_free(r); + BN_free(s); + } + if (ctx != NULL) { + BN_CTX_free(ctx); + } + BN_clear_free(&m); + BN_clear_free(&xr); + if (kinv != NULL) { + /* dsa->kinv is NULL now if we used it */ + 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, verify, 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, verify, DSA_R_BAD_Q_VALUE); + return 0; + } + + if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) { + OPENSSL_PUT_ERROR(DSA, verify, 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_LOCK_DSA, 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, verify, ERR_R_BN_LIB); + } + if (ctx != NULL) { + 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 (pub_key != NULL && dsa->pub_key == NULL) { + BN_free(pub_key); + } + if (priv_key != NULL && dsa->priv_key == NULL) { + BN_free(priv_key); + } + if (ctx != NULL) { + 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(); + mont = BN_MONT_CTX_new(); + if (ctx == NULL || mont == 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 (!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) { + if (ret->p) { + BN_free(ret->p); + } + if (ret->q) { + BN_free(ret->q); + } + if (ret->g) { + 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); + } + + if (mont != NULL) { + 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, +}; |