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>
68 static DSA_SIG
*dsa_do_sign(const unsigned char *dgst
, int dlen
, DSA
*dsa
);
69 static int dsa_sign_setup(DSA
*dsa
, BN_CTX
*ctx_in
, BIGNUM
**kinvp
, BIGNUM
**rp
);
70 static int dsa_do_verify(const unsigned char *dgst
, int dgst_len
, DSA_SIG
*sig
,
72 static int dsa_init(DSA
*dsa
);
73 static int dsa_finish(DSA
*dsa
);
74 static int dsa_mod_exp(DSA
*dsa
, BIGNUM
*rr
, BIGNUM
*a1
, BIGNUM
*p1
,
75 BIGNUM
*a2
, BIGNUM
*p2
, BIGNUM
*m
, BN_CTX
*ctx
,
76 BN_MONT_CTX
*in_mont
);
77 static int dsa_bn_mod_exp(DSA
*dsa
, BIGNUM
*r
, BIGNUM
*a
, const BIGNUM
*p
,
78 const BIGNUM
*m
, BN_CTX
*ctx
,
81 static DSA_METHOD openssl_dsa_meth
= {
94 DSA_METHOD
*DSA_OpenSSL(void)
96 return &openssl_dsa_meth
;
99 static DSA_SIG
*dsa_do_sign(const unsigned char *dgst
, int dlen
, DSA
*dsa
)
101 BIGNUM
*kinv
=NULL
,*r
=NULL
,*s
=NULL
;
105 int i
,reason
=ERR_R_BN_LIB
;
111 if (s
== NULL
) goto err
;
113 i
=BN_num_bytes(dsa
->q
); /* should be 20 */
114 if ((dlen
> i
) || (dlen
> 50))
116 reason
=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE
;
121 if (ctx
== NULL
) goto err
;
123 if ((dsa
->kinv
== NULL
) || (dsa
->r
== NULL
))
125 if (!DSA_sign_setup(dsa
,ctx
,&kinv
,&r
)) goto err
;
135 if (BN_bin2bn(dgst
,dlen
,&m
) == NULL
) goto err
;
137 /* Compute s = inv(k) (m + xr) mod q */
138 if (!BN_mod_mul(&xr
,dsa
->priv_key
,r
,dsa
->q
,ctx
)) goto err
;/* s = xr */
139 if (!BN_add(s
, &xr
, &m
)) goto err
; /* s = m + xr */
140 if (BN_cmp(s
,dsa
->q
) > 0)
142 if (!BN_mod_mul(s
,s
,kinv
,dsa
->q
,ctx
)) goto err
;
145 if (ret
== NULL
) goto err
;
152 DSAerr(DSA_F_DSA_DO_SIGN
,reason
);
156 if (ctx
!= NULL
) BN_CTX_free(ctx
);
159 if (kinv
!= NULL
) /* dsa->kinv is NULL now if we used it */
164 static int dsa_sign_setup(DSA
*dsa
, BN_CTX
*ctx_in
, BIGNUM
**kinvp
, BIGNUM
**rp
)
167 BIGNUM k
,*kinv
=NULL
,*r
=NULL
;
172 if ((ctx
=BN_CTX_new()) == NULL
) goto err
;
178 if ((r
=BN_new()) == NULL
) goto err
;
184 if (!BN_rand(&k
, BN_num_bits(dsa
->q
), 1, 0)) goto err
;
185 if (BN_cmp(&k
,dsa
->q
) >= 0)
186 BN_sub(&k
,&k
,dsa
->q
);
187 if (!BN_is_zero(&k
)) break;
190 if ((dsa
->method_mont_p
== NULL
) && (dsa
->flags
& DSA_FLAG_CACHE_MONT_P
))
192 if ((dsa
->method_mont_p
=(char *)BN_MONT_CTX_new()) != NULL
)
193 if (!BN_MONT_CTX_set((BN_MONT_CTX
*)dsa
->method_mont_p
,
194 dsa
->p
,ctx
)) goto err
;
197 /* Compute r = (g^k mod p) mod q */
198 if (!dsa
->meth
->bn_mod_exp(dsa
, r
,dsa
->g
,&k
,dsa
->p
,ctx
,
199 (BN_MONT_CTX
*)dsa
->method_mont_p
)) goto err
;
200 if (!BN_mod(r
,r
,dsa
->q
,ctx
)) goto err
;
202 /* Compute part of 's = inv(k) (m + xr) mod q' */
203 if ((kinv
=BN_mod_inverse(NULL
,&k
,dsa
->q
,ctx
)) == NULL
) goto err
;
205 if (*kinvp
!= NULL
) BN_clear_free(*kinvp
);
208 if (*rp
!= NULL
) BN_clear_free(*rp
);
214 DSAerr(DSA_F_DSA_SIGN_SETUP
,ERR_R_BN_LIB
);
215 if (kinv
!= NULL
) BN_clear_free(kinv
);
216 if (r
!= NULL
) BN_clear_free(r
);
218 if (ctx_in
== NULL
) BN_CTX_free(ctx
);
219 if (kinv
!= NULL
) BN_clear_free(kinv
);
224 static int dsa_do_verify(const unsigned char *dgst
, int dgst_len
, DSA_SIG
*sig
,
229 BN_MONT_CTX
*mont
=NULL
;
232 if ((ctx
=BN_CTX_new()) == NULL
) goto err
;
237 /* Calculate W = inv(S) mod Q
239 if ((BN_mod_inverse(&u2
,sig
->s
,dsa
->q
,ctx
)) == NULL
) goto err
;
242 if (BN_bin2bn(dgst
,dgst_len
,&u1
) == NULL
) goto err
;
244 /* u1 = M * w mod q */
245 if (!BN_mod_mul(&u1
,&u1
,&u2
,dsa
->q
,ctx
)) goto err
;
247 /* u2 = r * w mod q */
248 if (!BN_mod_mul(&u2
,sig
->r
,&u2
,dsa
->q
,ctx
)) goto err
;
250 if ((dsa
->method_mont_p
== NULL
) && (dsa
->flags
& DSA_FLAG_CACHE_MONT_P
))
252 if ((dsa
->method_mont_p
=(char *)BN_MONT_CTX_new()) != NULL
)
253 if (!BN_MONT_CTX_set((BN_MONT_CTX
*)dsa
->method_mont_p
,
254 dsa
->p
,ctx
)) goto err
;
256 mont
=(BN_MONT_CTX
*)dsa
->method_mont_p
;
263 /* v = ( g^u1 * y^u2 mod p ) mod q */
264 /* let t1 = g ^ u1 mod p */
265 if (!BN_mod_exp_mont(&t1
,dsa
->g
,&u1
,dsa
->p
,ctx
,mont
)) goto err
;
266 /* let t2 = y ^ u2 mod p */
267 if (!BN_mod_exp_mont(&t2
,dsa
->pub_key
,&u2
,dsa
->p
,ctx
,mont
)) goto err
;
268 /* let u1 = t1 * t2 mod p */
269 if (!BN_mod_mul(&u1
,&t1
,&t2
,dsa
->p
,ctx
)) goto err_bn
;
272 /* let u1 = u1 mod q */
273 if (!BN_mod(&u1
,&u1
,dsa
->q
,ctx
)) goto err
;
276 if (!dsa
->meth
->dsa_mod_exp(dsa
, &t1
,dsa
->g
,&u1
,dsa
->pub_key
,&u2
,
277 dsa
->p
,ctx
,mont
)) goto err
;
278 /* BN_copy(&u1,&t1); */
279 /* let u1 = u1 mod q */
280 if (!BN_mod(&u1
,&t1
,dsa
->q
,ctx
)) goto err
;
283 /* V is now in u1. If the signature is correct, it will be
285 ret
=(BN_ucmp(&u1
, sig
->r
) == 0);
288 if (ret
!= 1) DSAerr(DSA_F_DSA_DO_VERIFY
,ERR_R_BN_LIB
);
289 if (ctx
!= NULL
) BN_CTX_free(ctx
);
296 static int dsa_init(DSA
*dsa
)
298 dsa
->flags
|=DSA_FLAG_CACHE_MONT_P
;
302 static int dsa_finish(DSA
*dsa
)
304 if(dsa
->method_mont_p
)
305 BN_MONT_CTX_free((BN_MONT_CTX
*)dsa
->method_mont_p
);
309 static int dsa_mod_exp(DSA
*dsa
, BIGNUM
*rr
, BIGNUM
*a1
, BIGNUM
*p1
,
310 BIGNUM
*a2
, BIGNUM
*p2
, BIGNUM
*m
, BN_CTX
*ctx
,
311 BN_MONT_CTX
*in_mont
)
313 return BN_mod_exp2_mont(rr
, a1
, p1
, a2
, p2
, m
, ctx
, in_mont
);
316 static int dsa_bn_mod_exp(DSA
*dsa
, BIGNUM
*r
, BIGNUM
*a
, const BIGNUM
*p
,
317 const BIGNUM
*m
, BN_CTX
*ctx
,
320 return BN_mod_exp_mont(r
, a
, p
, m
, ctx
, m_ctx
);