1 /* crypto/dsa/dsa_ossl.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
59 /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
62 #include <openssl/bn.h>
63 #include <openssl/dsa.h>
64 #include <openssl/rand.h>
65 #include <openssl/asn1.h>
66 #include <openssl/err.h>
67 #ifndef OPENSSL_NO_ENGINE
68 # include <openssl/engine.h>
70 #include <openssl/fips.h>
74 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, FIPS_DSA_SIZE_T dlen,
76 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
78 static int dsa_do_verify(const unsigned char *dgst, FIPS_DSA_SIZE_T dgst_len,
79 DSA_SIG *sig, DSA *dsa);
80 static int dsa_init(DSA *dsa);
81 static int dsa_finish(DSA *dsa);
82 static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
83 BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
84 BN_MONT_CTX *in_mont);
85 static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
86 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
88 static const DSA_METHOD openssl_dsa_meth = {
89 "OpenSSL FIPS DSA method",
102 int FIPS_dsa_check(struct dsa_st *dsa)
104 if (dsa->meth != &openssl_dsa_meth
105 || dsa->meth->dsa_do_sign != dsa_do_sign
106 || dsa->meth->dsa_sign_setup != dsa_sign_setup
107 || dsa->meth->dsa_mod_exp != dsa_mod_exp
108 || dsa->meth->bn_mod_exp != dsa_bn_mod_exp
109 || dsa->meth->init != dsa_init || dsa->meth->finish != dsa_finish) {
110 FIPSerr(FIPS_F_FIPS_DSA_CHECK, FIPS_R_NON_FIPS_METHOD);
117 const DSA_METHOD *DSA_OpenSSL(void)
119 return &openssl_dsa_meth;
122 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, FIPS_DSA_SIZE_T dlen,
125 BIGNUM *kinv = NULL, *r = NULL, *s = NULL;
129 int i, reason = ERR_R_BN_LIB;
132 if (FIPS_selftest_failed()) {
133 FIPSerr(FIPS_F_DSA_DO_SIGN, FIPS_R_FIPS_SELFTEST_FAILED);
138 && (BN_num_bits(dsa->p) < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS)) {
139 DSAerr(DSA_F_DSA_DO_SIGN, DSA_R_KEY_SIZE_TOO_SMALL);
146 if (!dsa->p || !dsa->q || !dsa->g) {
147 reason = DSA_R_MISSING_PARAMETERS;
155 i = BN_num_bytes(dsa->q); /* should be 20 */
156 if ((dlen > i) || (dlen > 50)) {
157 reason = DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
165 if (!dsa->meth->dsa_sign_setup(dsa, ctx, &kinv, &r))
168 if (BN_bin2bn(dgst, dlen, &m) == NULL)
171 /* Compute s = inv(k) (m + xr) mod q */
172 if (!BN_mod_mul(&xr, dsa->priv_key, r, dsa->q, ctx))
173 goto err; /* s = xr */
174 if (!BN_add(s, &xr, &m))
175 goto err; /* s = m + xr */
176 if (BN_cmp(s, dsa->q) > 0)
177 BN_sub(s, s, dsa->q);
178 if (!BN_mod_mul(s, s, kinv, dsa->q, ctx))
189 DSAerr(DSA_F_DSA_DO_SIGN, reason);
197 if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
202 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
206 BIGNUM k, kq, *K, *kinv = NULL, *r = NULL;
209 if (!dsa->p || !dsa->q || !dsa->g) {
210 DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS);
217 if (ctx_in == NULL) {
218 if ((ctx = BN_CTX_new()) == NULL)
223 if ((r = BN_new()) == NULL)
228 if (!BN_rand_range(&k, dsa->q))
230 while (BN_is_zero(&k)) ;
231 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
232 BN_set_flags(&k, BN_FLG_CONSTTIME);
235 if (dsa->flags & DSA_FLAG_CACHE_MONT_P) {
236 if (!BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p,
237 CRYPTO_LOCK_DSA, dsa->p, ctx))
241 /* Compute r = (g^k mod p) mod q */
243 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
244 if (!BN_copy(&kq, &k))
248 * We do not want timing information to leak the length of k, so we
249 * compute g^k using an equivalent exponent of fixed length. (This
250 * is a kludge that we need because the BN_mod_exp_mont() does not
251 * let us specify the desired timing behaviour.)
254 if (!BN_add(&kq, &kq, dsa->q))
256 if (BN_num_bits(&kq) <= BN_num_bits(dsa->q)) {
257 if (!BN_add(&kq, &kq, dsa->q))
265 if (!dsa->meth->bn_mod_exp(dsa, r, dsa->g, K, dsa->p, ctx,
266 (BN_MONT_CTX *)dsa->method_mont_p))
268 if (!BN_mod(r, r, dsa->q, ctx))
271 /* Compute part of 's = inv(k) (m + xr) mod q' */
272 if ((kinv = BN_mod_inverse(NULL, &k, dsa->q, ctx)) == NULL)
276 BN_clear_free(*kinvp);
285 DSAerr(DSA_F_DSA_SIGN_SETUP, ERR_R_BN_LIB);
300 static int dsa_do_verify(const unsigned char *dgst, FIPS_DSA_SIZE_T dgst_len,
301 DSA_SIG *sig, DSA *dsa)
305 BN_MONT_CTX *mont = NULL;
308 if (!dsa->p || !dsa->q || !dsa->g) {
309 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MISSING_PARAMETERS);
313 if (FIPS_selftest_failed()) {
314 FIPSerr(FIPS_F_DSA_DO_VERIFY, FIPS_R_FIPS_SELFTEST_FAILED);
318 if (BN_num_bits(dsa->q) != 160) {
319 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_BAD_Q_VALUE);
323 if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
324 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MODULUS_TOO_LARGE);
329 && (BN_num_bits(dsa->p) < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS)) {
330 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_KEY_SIZE_TOO_SMALL);
338 if ((ctx = BN_CTX_new()) == NULL)
341 if (BN_is_zero(sig->r) || sig->r->neg || BN_ucmp(sig->r, dsa->q) >= 0) {
345 if (BN_is_zero(sig->s) || sig->s->neg || BN_ucmp(sig->s, dsa->q) >= 0) {
351 * Calculate W = inv(S) mod Q save W in u2
353 if ((BN_mod_inverse(&u2, sig->s, dsa->q, ctx)) == NULL)
357 if (BN_bin2bn(dgst, dgst_len, &u1) == NULL)
360 /* u1 = M * w mod q */
361 if (!BN_mod_mul(&u1, &u1, &u2, dsa->q, ctx))
364 /* u2 = r * w mod q */
365 if (!BN_mod_mul(&u2, sig->r, &u2, dsa->q, ctx))
368 if (dsa->flags & DSA_FLAG_CACHE_MONT_P) {
369 mont = BN_MONT_CTX_set_locked((BN_MONT_CTX **)&dsa->method_mont_p,
370 CRYPTO_LOCK_DSA, dsa->p, ctx);
379 /* v = ( g^u1 * y^u2 mod p ) mod q */
380 /* let t1 = g ^ u1 mod p */
381 if (!BN_mod_exp_mont(&t1, dsa->g, &u1, dsa->p, ctx, mont))
383 /* let t2 = y ^ u2 mod p */
384 if (!BN_mod_exp_mont(&t2, dsa->pub_key, &u2, dsa->p, ctx, mont))
386 /* let u1 = t1 * t2 mod p */
387 if (!BN_mod_mul(&u1, &t1, &t2, dsa->p, ctx))
391 /* let u1 = u1 mod q */
392 if (!BN_mod(&u1, &u1, dsa->q, ctx))
396 if (!dsa->meth->dsa_mod_exp(dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2,
399 /* BN_copy(&u1,&t1); */
400 /* let u1 = u1 mod q */
401 if (!BN_mod(&u1, &t1, dsa->q, ctx))
406 * V is now in u1. If the signature is correct, it will be equal to R.
408 ret = (BN_ucmp(&u1, sig->r) == 0);
412 DSAerr(DSA_F_DSA_DO_VERIFY, ERR_R_BN_LIB);
421 static int dsa_init(DSA *dsa)
423 FIPS_selftest_check();
424 dsa->flags |= DSA_FLAG_CACHE_MONT_P;
428 static int dsa_finish(DSA *dsa)
430 if (dsa->method_mont_p)
431 BN_MONT_CTX_free((BN_MONT_CTX *)dsa->method_mont_p);
435 static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
436 BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
437 BN_MONT_CTX *in_mont)
439 return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont);
442 static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
443 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
445 return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
448 #else /* ndef OPENSSL_FIPS */
450 static void *dummy = &dummy;
452 #endif /* ndef OPENSSL_FIPS */