1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.]
58 /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
61 #include "internal/cryptlib.h"
62 #include <openssl/bn.h>
63 #include <openssl/sha.h>
65 #include <openssl/rand.h>
66 #include <openssl/asn1.h>
68 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
69 static int dsa_sign_setup_no_digest(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
71 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
72 BIGNUM **rp, const unsigned char *dgst, int dlen);
73 static int dsa_do_verify(const unsigned char *dgst, int dgst_len,
74 DSA_SIG *sig, DSA *dsa);
75 static int dsa_init(DSA *dsa);
76 static int dsa_finish(DSA *dsa);
78 static DSA_METHOD openssl_dsa_meth = {
81 dsa_sign_setup_no_digest,
83 NULL, /* dsa_mod_exp, */
84 NULL, /* dsa_bn_mod_exp, */
94 * These macro wrappers replace attempts to use the dsa_mod_exp() and
95 * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of
96 * having a the macro work as an expression by bundling an "err_instr". So;
98 * if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,
99 * dsa->method_mont_p)) goto err;
101 * can be replaced by;
103 * DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx,
104 * dsa->method_mont_p);
107 #define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \
110 if ((dsa)->meth->dsa_mod_exp) \
111 _tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \
112 (a2), (p2), (m), (ctx), (in_mont)); \
114 _tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \
115 (m), (ctx), (in_mont)); \
116 if (!_tmp_res53) err_instr; \
118 #define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \
121 if ((dsa)->meth->bn_mod_exp) \
122 _tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \
123 (m), (ctx), (m_ctx)); \
125 _tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \
126 if (!_tmp_res53) err_instr; \
129 const DSA_METHOD *DSA_OpenSSL(void)
131 return &openssl_dsa_meth;
134 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
141 int reason = ERR_R_BN_LIB;
147 if (m == NULL || xr == NULL)
150 if (!dsa->p || !dsa->q || !dsa->g) {
151 reason = DSA_R_MISSING_PARAMETERS;
159 DSA_SIG_get0(&r, &s, ret);
165 if (!dsa_sign_setup(dsa, ctx, &kinv, &r, dgst, dlen))
168 if (dlen > BN_num_bytes(dsa->q))
170 * if the digest length is greater than the size of q use the
171 * BN_num_bits(dsa->q) leftmost bits of the digest, see fips 186-3,
174 dlen = BN_num_bytes(dsa->q);
175 if (BN_bin2bn(dgst, dlen, m) == NULL)
178 /* Compute s = inv(k) (m + xr) mod q */
179 if (!BN_mod_mul(xr, dsa->priv_key, r, dsa->q, ctx))
180 goto err; /* s = xr */
181 if (!BN_add(s, xr, m))
182 goto err; /* s = m + xr */
183 if (BN_cmp(s, dsa->q) > 0)
184 if (!BN_sub(s, s, dsa->q))
186 if (!BN_mod_mul(s, s, kinv, dsa->q, ctx))
190 * Redo if r or s is zero as required by FIPS 186-3: this is very
193 if (BN_is_zero(r) || BN_is_zero(s))
200 DSAerr(DSA_F_DSA_DO_SIGN, reason);
211 static int dsa_sign_setup_no_digest(DSA *dsa, BN_CTX *ctx_in,
212 BIGNUM **kinvp, BIGNUM **rp)
214 return dsa_sign_setup(dsa, ctx_in, kinvp, rp, NULL, 0);
217 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in,
218 BIGNUM **kinvp, BIGNUM **rp,
219 const unsigned char *dgst, int dlen)
222 BIGNUM *k, *kq, *K, *kinv = NULL, *r = *rp;
225 if (!dsa->p || !dsa->q || !dsa->g) {
226 DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS);
232 if (k == NULL || kq == NULL)
235 if (ctx_in == NULL) {
236 if ((ctx = BN_CTX_new()) == NULL)
245 * We calculate k from SHA512(private_key + H(message) + random).
246 * This protects the private key from a weak PRNG.
248 if (!BN_generate_dsa_nonce(k, dsa->q, dsa->priv_key, dgst,
251 } else if (!BN_rand_range(k, dsa->q))
253 } while (BN_is_zero(k));
255 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
256 BN_set_flags(k, BN_FLG_CONSTTIME);
259 if (dsa->flags & DSA_FLAG_CACHE_MONT_P) {
260 if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p,
261 dsa->lock, dsa->p, ctx))
265 /* Compute r = (g^k mod p) mod q */
267 if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) {
272 * We do not want timing information to leak the length of k, so we
273 * compute g^k using an equivalent exponent of fixed length. (This
274 * is a kludge that we need because the BN_mod_exp_mont() does not
275 * let us specify the desired timing behaviour.)
278 if (!BN_add(kq, kq, dsa->q))
280 if (BN_num_bits(kq) <= BN_num_bits(dsa->q)) {
281 if (!BN_add(kq, kq, dsa->q))
289 DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx,
291 if (!BN_mod(r, r, dsa->q, ctx))
294 /* Compute part of 's = inv(k) (m + xr) mod q' */
295 if ((kinv = BN_mod_inverse(NULL, k, dsa->q, ctx)) == NULL)
298 BN_clear_free(*kinvp);
304 DSAerr(DSA_F_DSA_SIGN_SETUP, ERR_R_BN_LIB);
312 static int dsa_do_verify(const unsigned char *dgst, int dgst_len,
313 DSA_SIG *sig, DSA *dsa)
316 BIGNUM *u1, *u2, *t1;
317 BN_MONT_CTX *mont = NULL;
320 if (!dsa->p || !dsa->q || !dsa->g) {
321 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MISSING_PARAMETERS);
325 i = BN_num_bits(dsa->q);
326 /* fips 186-3 allows only different sizes for q */
327 if (i != 160 && i != 224 && i != 256) {
328 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_BAD_Q_VALUE);
332 if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
333 DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MODULUS_TOO_LARGE);
340 if (u1 == NULL || u2 == NULL || t1 == NULL || ctx == NULL)
343 DSA_SIG_get0(&r, &s, sig);
345 if (BN_is_zero(r) || BN_is_negative(r) ||
346 BN_ucmp(r, dsa->q) >= 0) {
350 if (BN_is_zero(s) || BN_is_negative(s) ||
351 BN_ucmp(s, dsa->q) >= 0) {
357 * Calculate W = inv(S) mod Q save W in u2
359 if ((BN_mod_inverse(u2, s, dsa->q, ctx)) == NULL)
363 if (dgst_len > (i >> 3))
365 * if the digest length is greater than the size of q use the
366 * BN_num_bits(dsa->q) leftmost bits of the digest, see fips 186-3,
370 if (BN_bin2bn(dgst, dgst_len, u1) == NULL)
373 /* u1 = M * w mod q */
374 if (!BN_mod_mul(u1, u1, u2, dsa->q, ctx))
377 /* u2 = r * w mod q */
378 if (!BN_mod_mul(u2, r, u2, dsa->q, ctx))
381 if (dsa->flags & DSA_FLAG_CACHE_MONT_P) {
382 mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p,
383 dsa->lock, dsa->p, ctx);
388 DSA_MOD_EXP(goto err, dsa, t1, dsa->g, u1, dsa->pub_key, u2, dsa->p, ctx,
390 /* BN_copy(&u1,&t1); */
391 /* let u1 = u1 mod q */
392 if (!BN_mod(u1, t1, dsa->q, ctx))
396 * V is now in u1. If the signature is correct, it will be equal to R.
398 ret = (BN_ucmp(u1, r) == 0);
402 DSAerr(DSA_F_DSA_DO_VERIFY, ERR_R_BN_LIB);
410 static int dsa_init(DSA *dsa)
412 dsa->flags |= DSA_FLAG_CACHE_MONT_P;
416 static int dsa_finish(DSA *dsa)
418 BN_MONT_CTX_free(dsa->method_mont_p);