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d02b48c6 | 1 | /* crypto/dsa/dsa_vrf.c */ |
58964a49 | 2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
d02b48c6 RE |
3 | * All rights reserved. |
4 | * | |
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. | |
8 | * | |
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). | |
15 | * | |
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. | |
22 | * | |
23 | * Redistribution and use in source and binary forms, with or without | |
24 | * modification, are permitted provided that the following conditions | |
25 | * are met: | |
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)" | |
40 | * | |
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 | |
51 | * SUCH DAMAGE. | |
52 | * | |
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.] | |
57 | */ | |
58 | ||
a8da8918 | 59 | /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */ |
d02b48c6 RE |
60 | |
61 | #include <stdio.h> | |
62 | #include "cryptlib.h" | |
63 | #include "bn.h" | |
64 | #include "dsa.h" | |
65 | #include "rand.h" | |
66 | #include "asn1.h" | |
67 | #include "asn1_mac.h" | |
68 | ||
6b691a5c | 69 | int DSA_do_verify(unsigned char *dgst, int dgst_len, DSA_SIG *sig, DSA *dsa) |
d02b48c6 | 70 | { |
d02b48c6 | 71 | BN_CTX *ctx; |
a8da8918 | 72 | BIGNUM u1,u2,t1; |
dfeab068 | 73 | BN_MONT_CTX *mont=NULL; |
d02b48c6 RE |
74 | int ret = -1; |
75 | ||
dfeab068 | 76 | if ((ctx=BN_CTX_new()) == NULL) goto err; |
dfeab068 RE |
77 | BN_init(&u1); |
78 | BN_init(&u2); | |
dfeab068 | 79 | BN_init(&t1); |
d02b48c6 | 80 | |
d02b48c6 RE |
81 | /* Calculate W = inv(S) mod Q |
82 | * save W in u2 */ | |
a8da8918 | 83 | if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err; |
d02b48c6 RE |
84 | |
85 | /* save M in u1 */ | |
a8da8918 | 86 | if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err; |
d02b48c6 RE |
87 | |
88 | /* u1 = M * w mod q */ | |
a8da8918 | 89 | if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err; |
d02b48c6 RE |
90 | |
91 | /* u2 = r * w mod q */ | |
a8da8918 | 92 | if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err; |
d02b48c6 | 93 | |
dfeab068 RE |
94 | if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P)) |
95 | { | |
96 | if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL) | |
97 | if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p, | |
98 | dsa->p,ctx)) goto err; | |
99 | } | |
100 | mont=(BN_MONT_CTX *)dsa->method_mont_p; | |
101 | ||
102 | #if 0 | |
103 | { | |
104 | BIGNUM t2; | |
105 | ||
106 | BN_init(&t2); | |
d02b48c6 RE |
107 | /* v = ( g^u1 * y^u2 mod p ) mod q */ |
108 | /* let t1 = g ^ u1 mod p */ | |
a8da8918 | 109 | if (!BN_mod_exp_mont(&t1,dsa->g,&u1,dsa->p,ctx,mont)) goto err; |
d02b48c6 | 110 | /* let t2 = y ^ u2 mod p */ |
a8da8918 | 111 | if (!BN_mod_exp_mont(&t2,dsa->pub_key,&u2,dsa->p,ctx,mont)) goto err; |
d02b48c6 | 112 | /* let u1 = t1 * t2 mod p */ |
dfeab068 RE |
113 | if (!BN_mod_mul(&u1,&t1,&t2,dsa->p,ctx)) goto err_bn; |
114 | BN_free(&t2); | |
115 | } | |
116 | /* let u1 = u1 mod q */ | |
a8da8918 | 117 | if (!BN_mod(&u1,&u1,dsa->q,ctx)) goto err; |
dfeab068 RE |
118 | #else |
119 | { | |
120 | if (!BN_mod_exp2_mont(&t1,dsa->g,&u1,dsa->pub_key,&u2,dsa->p,ctx,mont)) | |
a8da8918 | 121 | goto err; |
dfeab068 | 122 | /* BN_copy(&u1,&t1); */ |
d02b48c6 | 123 | /* let u1 = u1 mod q */ |
a8da8918 | 124 | if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err; |
dfeab068 RE |
125 | } |
126 | #endif | |
d02b48c6 RE |
127 | /* V is now in u1. If the signature is correct, it will be |
128 | * equal to R. */ | |
a8da8918 UM |
129 | ret=(BN_ucmp(&u1, sig->r) == 0); |
130 | ||
131 | err: | |
132 | if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB); | |
d02b48c6 | 133 | if (ctx != NULL) BN_CTX_free(ctx); |
dfeab068 RE |
134 | BN_free(&u1); |
135 | BN_free(&u2); | |
136 | BN_free(&t1); | |
a8da8918 UM |
137 | return(ret); |
138 | } | |
139 | ||
140 | /* data has already been hashed (probably with SHA or SHA-1). */ | |
141 | /* returns | |
142 | * 1: correct signature | |
143 | * 0: incorrect signature | |
144 | * -1: error | |
145 | */ | |
6b691a5c UM |
146 | int DSA_verify(int type, unsigned char *dgst, int dgst_len, |
147 | unsigned char *sigbuf, int siglen, DSA *dsa) | |
a8da8918 UM |
148 | { |
149 | DSA_SIG *s; | |
150 | int ret=-1; | |
151 | ||
152 | s = DSA_SIG_new(); | |
153 | if (s == NULL) return(ret); | |
154 | if (d2i_DSA_SIG(&s,&sigbuf,siglen) == NULL) goto err; | |
155 | ret=DSA_do_verify(dgst,dgst_len,s,dsa); | |
156 | err: | |
157 | DSA_SIG_free(s); | |
d02b48c6 RE |
158 | return(ret); |
159 | } |