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>
67 #include <openssl/engine.h>
69 static DSA_SIG
*dsa_do_sign(const unsigned char *dgst
, int dlen
, DSA
*dsa
);
70 static int dsa_sign_setup(DSA
*dsa
, BN_CTX
*ctx_in
, BIGNUM
**kinvp
, BIGNUM
**rp
);
71 static int dsa_do_verify(const unsigned char *dgst
, int dgst_len
, DSA_SIG
*sig
,
73 static int dsa_init(DSA
*dsa
);
74 static int dsa_finish(DSA
*dsa
);
75 static int dsa_mod_exp(DSA
*dsa
, BIGNUM
*rr
, BIGNUM
*a1
, BIGNUM
*p1
,
76 BIGNUM
*a2
, BIGNUM
*p2
, BIGNUM
*m
, BN_CTX
*ctx
,
77 BN_MONT_CTX
*in_mont
);
78 static int dsa_bn_mod_exp(DSA
*dsa
, BIGNUM
*r
, BIGNUM
*a
, const BIGNUM
*p
,
79 const BIGNUM
*m
, BN_CTX
*ctx
,
82 static DSA_METHOD openssl_dsa_meth
= {
95 const DSA_METHOD
*DSA_OpenSSL(void)
97 return &openssl_dsa_meth
;
100 static DSA_SIG
*dsa_do_sign(const unsigned char *dgst
, int dlen
, DSA
*dsa
)
102 BIGNUM
*kinv
=NULL
,*r
=NULL
,*s
=NULL
;
106 int i
,reason
=ERR_R_BN_LIB
;
109 if (!dsa
->p
|| !dsa
->q
|| !dsa
->g
)
111 reason
=DSA_R_MISSING_PARAMETERS
;
117 if (s
== NULL
) goto err
;
119 i
=BN_num_bytes(dsa
->q
); /* should be 20 */
120 if ((dlen
> i
) || (dlen
> 50))
122 reason
=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE
;
127 if (ctx
== NULL
) goto err
;
129 if ((dsa
->kinv
== NULL
) || (dsa
->r
== NULL
))
131 if (!DSA_sign_setup(dsa
,ctx
,&kinv
,&r
)) goto err
;
141 if (BN_bin2bn(dgst
,dlen
,&m
) == NULL
) goto err
;
143 /* Compute s = inv(k) (m + xr) mod q */
144 if (!BN_mod_mul(&xr
,dsa
->priv_key
,r
,dsa
->q
,ctx
)) goto err
;/* s = xr */
145 if (!BN_add(s
, &xr
, &m
)) goto err
; /* s = m + xr */
146 if (BN_cmp(s
,dsa
->q
) > 0)
148 if (!BN_mod_mul(s
,s
,kinv
,dsa
->q
,ctx
)) goto err
;
151 if (ret
== NULL
) goto err
;
158 DSAerr(DSA_F_DSA_DO_SIGN
,reason
);
162 if (ctx
!= NULL
) BN_CTX_free(ctx
);
165 if (kinv
!= NULL
) /* dsa->kinv is NULL now if we used it */
170 static int dsa_sign_setup(DSA
*dsa
, BN_CTX
*ctx_in
, BIGNUM
**kinvp
, BIGNUM
**rp
)
173 BIGNUM k
,*kinv
=NULL
,*r
=NULL
;
176 if (!dsa
->p
|| !dsa
->q
|| !dsa
->g
)
178 DSAerr(DSA_F_DSA_SIGN_SETUP
,DSA_R_MISSING_PARAMETERS
);
183 if ((ctx
=BN_CTX_new()) == NULL
) goto err
;
189 if ((r
=BN_new()) == NULL
) goto err
;
194 if (!BN_rand_range(&k
, dsa
->q
)) goto err
;
195 while (BN_is_zero(&k
));
197 if ((dsa
->method_mont_p
== NULL
) && (dsa
->flags
& DSA_FLAG_CACHE_MONT_P
))
199 if ((dsa
->method_mont_p
=(char *)BN_MONT_CTX_new()) != NULL
)
200 if (!BN_MONT_CTX_set((BN_MONT_CTX
*)dsa
->method_mont_p
,
201 dsa
->p
,ctx
)) goto err
;
204 /* Compute r = (g^k mod p) mod q */
205 if (!dsa
->meth
->bn_mod_exp(dsa
, r
,dsa
->g
,&k
,dsa
->p
,ctx
,
206 (BN_MONT_CTX
*)dsa
->method_mont_p
)) goto err
;
207 if (!BN_mod(r
,r
,dsa
->q
,ctx
)) goto err
;
209 /* Compute part of 's = inv(k) (m + xr) mod q' */
210 if ((kinv
=BN_mod_inverse(NULL
,&k
,dsa
->q
,ctx
)) == NULL
) goto err
;
212 if (*kinvp
!= NULL
) BN_clear_free(*kinvp
);
215 if (*rp
!= NULL
) BN_clear_free(*rp
);
221 DSAerr(DSA_F_DSA_SIGN_SETUP
,ERR_R_BN_LIB
);
222 if (kinv
!= NULL
) BN_clear_free(kinv
);
223 if (r
!= NULL
) BN_clear_free(r
);
225 if (ctx_in
== NULL
) BN_CTX_free(ctx
);
226 if (kinv
!= NULL
) BN_clear_free(kinv
);
231 static int dsa_do_verify(const unsigned char *dgst
, int dgst_len
, DSA_SIG
*sig
,
236 BN_MONT_CTX
*mont
=NULL
;
238 if (!dsa
->p
|| !dsa
->q
|| !dsa
->g
)
240 DSAerr(DSA_F_DSA_DO_VERIFY
,DSA_R_MISSING_PARAMETERS
);
244 if ((ctx
=BN_CTX_new()) == NULL
) goto err
;
249 if (BN_is_zero(sig
->r
) || BN_get_sign(sig
->r
) ||
250 BN_ucmp(sig
->r
, dsa
->q
) >= 0)
255 if (BN_is_zero(sig
->s
) || BN_get_sign(sig
->s
) ||
256 BN_ucmp(sig
->s
, dsa
->q
) >= 0)
262 /* Calculate W = inv(S) mod Q
264 if ((BN_mod_inverse(&u2
,sig
->s
,dsa
->q
,ctx
)) == NULL
) goto err
;
267 if (BN_bin2bn(dgst
,dgst_len
,&u1
) == NULL
) goto err
;
269 /* u1 = M * w mod q */
270 if (!BN_mod_mul(&u1
,&u1
,&u2
,dsa
->q
,ctx
)) goto err
;
272 /* u2 = r * w mod q */
273 if (!BN_mod_mul(&u2
,sig
->r
,&u2
,dsa
->q
,ctx
)) goto err
;
275 if ((dsa
->method_mont_p
== NULL
) && (dsa
->flags
& DSA_FLAG_CACHE_MONT_P
))
277 if ((dsa
->method_mont_p
=(char *)BN_MONT_CTX_new()) != NULL
)
278 if (!BN_MONT_CTX_set((BN_MONT_CTX
*)dsa
->method_mont_p
,
279 dsa
->p
,ctx
)) goto err
;
281 mont
=(BN_MONT_CTX
*)dsa
->method_mont_p
;
288 /* v = ( g^u1 * y^u2 mod p ) mod q */
289 /* let t1 = g ^ u1 mod p */
290 if (!BN_mod_exp_mont(&t1
,dsa
->g
,&u1
,dsa
->p
,ctx
,mont
)) goto err
;
291 /* let t2 = y ^ u2 mod p */
292 if (!BN_mod_exp_mont(&t2
,dsa
->pub_key
,&u2
,dsa
->p
,ctx
,mont
)) goto err
;
293 /* let u1 = t1 * t2 mod p */
294 if (!BN_mod_mul(&u1
,&t1
,&t2
,dsa
->p
,ctx
)) goto err_bn
;
297 /* let u1 = u1 mod q */
298 if (!BN_mod(&u1
,&u1
,dsa
->q
,ctx
)) goto err
;
301 if (!dsa
->meth
->dsa_mod_exp(dsa
, &t1
,dsa
->g
,&u1
,dsa
->pub_key
,&u2
,
302 dsa
->p
,ctx
,mont
)) goto err
;
303 /* BN_copy(&u1,&t1); */
304 /* let u1 = u1 mod q */
305 if (!BN_mod(&u1
,&t1
,dsa
->q
,ctx
)) goto err
;
308 /* V is now in u1. If the signature is correct, it will be
310 ret
=(BN_ucmp(&u1
, sig
->r
) == 0);
313 if (ret
!= 1) DSAerr(DSA_F_DSA_DO_VERIFY
,ERR_R_BN_LIB
);
314 if (ctx
!= NULL
) BN_CTX_free(ctx
);
321 static int dsa_init(DSA
*dsa
)
323 dsa
->flags
|=DSA_FLAG_CACHE_MONT_P
;
327 static int dsa_finish(DSA
*dsa
)
329 if(dsa
->method_mont_p
)
330 BN_MONT_CTX_free((BN_MONT_CTX
*)dsa
->method_mont_p
);
334 static int dsa_mod_exp(DSA
*dsa
, BIGNUM
*rr
, BIGNUM
*a1
, BIGNUM
*p1
,
335 BIGNUM
*a2
, BIGNUM
*p2
, BIGNUM
*m
, BN_CTX
*ctx
,
336 BN_MONT_CTX
*in_mont
)
338 return BN_mod_exp2_mont(rr
, a1
, p1
, a2
, p2
, m
, ctx
, in_mont
);
341 static int dsa_bn_mod_exp(DSA
*dsa
, BIGNUM
*r
, BIGNUM
*a
, const BIGNUM
*p
,
342 const BIGNUM
*m
, BN_CTX
*ctx
,
345 return BN_mod_exp_mont(r
, a
, p
, m
, ctx
, m_ctx
);