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> */
63 #include <openssl/bn.h>
64 #include <openssl/dsa.h>
65 #include <openssl/rand.h>
66 #include <openssl/asn1.h>
70 static DSA_SIG
*dsa_do_sign(const unsigned char *dgst
, int dlen
, DSA
*dsa
);
71 static int dsa_sign_setup(DSA
*dsa
, BN_CTX
*ctx_in
, BIGNUM
**kinvp
,
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
= {
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
)
136 BIGNUM
*kinv
= NULL
, *r
= NULL
, *s
= NULL
;
140 int i
, reason
= ERR_R_BN_LIB
;
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
->kinv
== NULL
) || (dsa
->r
== NULL
)) {
166 if (!DSA_sign_setup(dsa
, ctx
, &kinv
, &r
))
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
))
197 DSAerr(DSA_F_DSA_DO_SIGN
, reason
);
205 if (kinv
!= NULL
) /* dsa->kinv is NULL now if we used it */
210 static int dsa_sign_setup(DSA
*dsa
, BN_CTX
*ctx_in
, BIGNUM
**kinvp
,
214 BIGNUM k
, kq
, *K
, *kinv
= NULL
, *r
= NULL
;
217 if (!dsa
->p
|| !dsa
->q
|| !dsa
->g
) {
218 DSAerr(DSA_F_DSA_SIGN_SETUP
, DSA_R_MISSING_PARAMETERS
);
225 if (ctx_in
== NULL
) {
226 if ((ctx
= BN_CTX_new()) == NULL
)
231 if ((r
= BN_new()) == NULL
)
236 if (!BN_rand_range(&k
, dsa
->q
))
238 while (BN_is_zero(&k
)) ;
239 if ((dsa
->flags
& DSA_FLAG_NO_EXP_CONSTTIME
) == 0) {
240 BN_set_flags(&k
, BN_FLG_CONSTTIME
);
243 if (dsa
->flags
& DSA_FLAG_CACHE_MONT_P
) {
244 if (!BN_MONT_CTX_set_locked(&dsa
->method_mont_p
,
245 CRYPTO_LOCK_DSA
, dsa
->p
, ctx
))
249 /* Compute r = (g^k mod p) mod q */
251 if ((dsa
->flags
& DSA_FLAG_NO_EXP_CONSTTIME
) == 0) {
252 if (!BN_copy(&kq
, &k
))
256 * We do not want timing information to leak the length of k, so we
257 * compute g^k using an equivalent exponent of fixed length. (This
258 * is a kludge that we need because the BN_mod_exp_mont() does not
259 * let us specify the desired timing behaviour.)
262 if (!BN_add(&kq
, &kq
, dsa
->q
))
264 if (BN_num_bits(&kq
) <= BN_num_bits(dsa
->q
)) {
265 if (!BN_add(&kq
, &kq
, dsa
->q
))
273 DSA_BN_MOD_EXP(goto err
, dsa
, r
, dsa
->g
, K
, dsa
->p
, ctx
,
275 if (!BN_mod(r
, r
, dsa
->q
, ctx
))
278 /* Compute part of 's = inv(k) (m + xr) mod q' */
279 if ((kinv
= BN_mod_inverse(NULL
, &k
, dsa
->q
, ctx
)) == NULL
)
283 BN_clear_free(*kinvp
);
292 DSAerr(DSA_F_DSA_SIGN_SETUP
, ERR_R_BN_LIB
);
307 static int dsa_do_verify(const unsigned char *dgst
, int dgst_len
,
308 DSA_SIG
*sig
, DSA
*dsa
)
312 BN_MONT_CTX
*mont
= NULL
;
314 if (!dsa
->p
|| !dsa
->q
|| !dsa
->g
) {
315 DSAerr(DSA_F_DSA_DO_VERIFY
, DSA_R_MISSING_PARAMETERS
);
319 if (BN_num_bits(dsa
->q
) != 160) {
320 DSAerr(DSA_F_DSA_DO_VERIFY
, DSA_R_BAD_Q_VALUE
);
324 if (BN_num_bits(dsa
->p
) > OPENSSL_DSA_MAX_MODULUS_BITS
) {
325 DSAerr(DSA_F_DSA_DO_VERIFY
, DSA_R_MODULUS_TOO_LARGE
);
333 if ((ctx
= BN_CTX_new()) == NULL
)
336 if (BN_is_zero(sig
->r
) || BN_is_negative(sig
->r
) ||
337 BN_ucmp(sig
->r
, dsa
->q
) >= 0) {
341 if (BN_is_zero(sig
->s
) || BN_is_negative(sig
->s
) ||
342 BN_ucmp(sig
->s
, dsa
->q
) >= 0) {
348 * Calculate W = inv(S) mod Q save W in u2
350 if ((BN_mod_inverse(&u2
, sig
->s
, dsa
->q
, ctx
)) == NULL
)
354 if (BN_bin2bn(dgst
, dgst_len
, &u1
) == NULL
)
357 /* u1 = M * w mod q */
358 if (!BN_mod_mul(&u1
, &u1
, &u2
, dsa
->q
, ctx
))
361 /* u2 = r * w mod q */
362 if (!BN_mod_mul(&u2
, sig
->r
, &u2
, dsa
->q
, ctx
))
365 if (dsa
->flags
& DSA_FLAG_CACHE_MONT_P
) {
366 mont
= BN_MONT_CTX_set_locked(&dsa
->method_mont_p
,
367 CRYPTO_LOCK_DSA
, dsa
->p
, ctx
);
372 DSA_MOD_EXP(goto err
, dsa
, &t1
, dsa
->g
, &u1
, dsa
->pub_key
, &u2
, dsa
->p
,
374 /* BN_copy(&u1,&t1); */
375 /* let u1 = u1 mod q */
376 if (!BN_mod(&u1
, &t1
, dsa
->q
, ctx
))
380 * V is now in u1. If the signature is correct, it will be equal to R.
382 ret
= (BN_ucmp(&u1
, sig
->r
) == 0);
386 * XXX: surely this is wrong - if ret is 0, it just didn't verify; there
387 * is no error in BN. Test should be ret == -1 (Ben)
390 DSAerr(DSA_F_DSA_DO_VERIFY
, ERR_R_BN_LIB
);
399 static int dsa_init(DSA
*dsa
)
401 dsa
->flags
|= DSA_FLAG_CACHE_MONT_P
;
405 static int dsa_finish(DSA
*dsa
)
407 if (dsa
->method_mont_p
)
408 BN_MONT_CTX_free(dsa
->method_mont_p
);