3 * $Id: dsa-sign.c,v 1.1 1999/11/19 19:28:00 mdw Exp $
5 * DSA signing operation
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * Catacomb is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
32 * $Log: dsa-sign.c,v $
33 * Revision 1.1 1999/11/19 19:28:00 mdw
34 * Implementation of the Digital Signature Algorithm.
38 /*----- Header files ------------------------------------------------------*/
44 /*----- Main code ---------------------------------------------------------*/
46 /* --- @dsa_mksig@ --- *
48 * Arguments: @const dsa_param *dp@ = pointer to DSA parameters
49 * @const mp *a@ = secret signing key
50 * @const mp *m@ = message to be signed
51 * @const mp *k@ = random data
52 * @mp **rr, **ss@ = where to put output parameters
56 * Use: Computes a DSA signature of a message.
59 void dsa_mksig(const dsa_param
*dp
, const mp
*a
, const mp
*m
, const mp
*k
,
66 /* --- Create the Montgomery contexts --- */
68 mpmont_create(&pm
, dp
->p
);
69 mpmont_create(&qm
, dp
->q
);
71 /* --- Compute %$r = (g^k \bmod p) \bmod q$% --- */
73 r
= mpmont_exp(&pm
, dp
->g
, k
);
74 mp_div(0, &r
, r
, dp
->q
);
77 /* --- Compute %$k^{-1} \bmod q$% --- */
79 mp_gcd(0, 0, &k1
, dp
->q
, (mp
*)k
);
81 /* --- Now for %$k^{-1}(m + ar)$% --- */
83 rrr
= mpmont_mul(&qm
, MP_NEW
, r
, qm
.r2
);
84 ar
= mpmont_mul(&qm
, MP_NEW
, a
, rrr
);
85 ar
= mp_add(ar
, ar
, m
);
86 if (MP_CMP(ar
, >=, dp
->q
))
87 ar
= mp_sub(ar
, ar
, dp
->q
);
88 rrr
= mpmont_mul(&qm
, rrr
, ar
, qm
.r2
);
89 ar
= mpmont_mul(&qm
, ar
, rrr
, k1
);
92 /* --- Tidy things up a little --- */
100 /* --- @dsa_sign@ --- *
102 * Arguments: @dsa_param *dp@ = pointer to DSA parameters
103 * @mp *a@ = pointer to secret signing key
104 * @const void *m@ = pointer to message
105 * @size_t msz@ = size of the message
106 * @const void *k@ = secret random data for securing signature
107 * @size_t ksz@ = size of secret data
108 * @void *r@ = pointer to output space for @r@
109 * @size_t rsz@ = size of output space for @r@
110 * @void *s@ = pointer to output space for @s@
111 * @size_t ssz@ = size of output space for @s@
115 * Use: Signs a message, storing the results in a big-endian binary
119 void dsa_sign(dsa_param
*dp
, mp
*a
,
120 const void *m
, size_t msz
, const void *k
, size_t ksz
,
121 void *r
, size_t rsz
, void *s
, size_t ssz
)
123 mp
*mm
= mp_loadb(MP_NEW
, m
, msz
);
124 mp
*km
= mp_loadb(MP_NEW
, k
, ksz
);
126 dsa_mksig(dp
, a
, mm
, km
, &rm
, &sm
);
127 mp_storeb(rm
, r
, rsz
);
128 mp_storeb(sm
, s
, ssz
);
129 mp_drop(mm
); mp_drop(km
);
130 mp_drop(rm
); mp_drop(sm
);
133 /*----- Test rig ----------------------------------------------------------*/
137 #include <mLib/testrig.h>
141 static int verify(dstr
*v
)
146 octet hash
[SHA_HASHSZ
];
150 dp
.q
= *(mp
**)v
[0].buf
;
151 dp
.p
= *(mp
**)v
[1].buf
;
152 dp
.g
= *(mp
**)v
[2].buf
;
153 x
= *(mp
**)v
[3].buf
;
156 sha_hash(&c
, v
[4].buf
, v
[4].len
);
159 dsa_sign(&dp
, x
, hash
, sizeof(hash
), v
[5].buf
, v
[5].len
,
160 s
.r
, sizeof(s
.r
), s
.s
, sizeof(s
.s
));
162 if (v
[6].len
!= sizeof(s
.r
) || v
[7].len
!= sizeof(s
.s
) ||
163 memcmp(s
.r
, v
[6].buf
, sizeof(s
.r
)) != 0 ||
164 memcmp(s
.s
, v
[7].buf
, sizeof(s
.s
)) != 0) {
165 fputs("\n*** signature failed", stderr
);
166 fputs("\nq = ", stderr
); mp_writefile(dp
.q
, stderr
, 16);
167 fputs("\np = ", stderr
); mp_writefile(dp
.p
, stderr
, 16);
168 fputs("\ng = ", stderr
); mp_writefile(dp
.g
, stderr
, 16);
169 fputs("\nx = ", stderr
); mp_writefile(x
, stderr
, 16);
170 fprintf(stderr
, "\nmessage = `%s'", v
[4].buf
);
171 fputs("\nk = ", stderr
); type_hex
.dump(&v
[5], stderr
);
172 fputs("\nR = ", stderr
); type_hex
.dump(&v
[6], stderr
);
173 fputs("\nS = ", stderr
); type_hex
.dump(&v
[7], stderr
);
177 m
= mp_loadb(m
, hash
, sizeof(hash
));
178 fputs("\nm = ", stderr
); mp_writefile(m
, stderr
, 16);
179 m
= mp_loadb(m
, s
.r
, sizeof(s
.r
));
180 fputs("\nr = ", stderr
); mp_writefile(m
, stderr
, 16);
181 m
= mp_loadb(m
, s
.s
, sizeof(s
.s
));
182 fputs("\ns = ", stderr
); mp_writefile(m
, stderr
, 16);
197 static test_chunk tests
[] = {
199 { &type_mp
, &type_mp
, &type_mp
, &type_mp
,
200 &type_string
, &type_hex
, &type_hex
, &type_hex
, 0 } },
204 int main(int argc
, char *argv
[])
207 test_run(argc
, argv
, tests
, SRCDIR
"/tests/dsa");
213 /*----- That's all, folks -------------------------------------------------*/