3 * $Id: dsa-sign.c,v 1.3 2004/04/08 01:36:15 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 /*----- Header files ------------------------------------------------------*/
34 #include "mpbarrett.h"
37 /*----- Main code ---------------------------------------------------------*/
39 /* --- @dsa_mksig@ --- *
41 * Arguments: @const dsa_param *dp@ = pointer to DSA parameters
42 * @mp *a@ = secret signing key
43 * @mp *m@ = message to be signed
44 * @mp *k@ = random data
45 * @mp **rr, **ss@ = where to put output parameters
49 * Use: Computes a DSA signature of a message.
52 void dsa_mksig(const dsa_param
*dp
, mp
*a
, mp
*m
, mp
*k
, mp
**rr
, mp
**ss
)
59 /* --- Compute %$r = (g^k \bmod p) \bmod q$% --- */
61 mpmont_create(&pm
, dp
->p
);
62 r
= mpmont_exp(&pm
, MP_NEW
, dp
->g
, k
);
64 mp_div(0, &r
, r
, dp
->q
);
66 /* --- Compute %$k^{-1} \bmod q$% --- */
68 k1
= mp_modinv(MP_NEW
, k
, dp
->q
);
70 /* --- Now for %$k^{-1}(m + ar)$% --- */
72 mpbarrett_create(&qb
, dp
->q
);
73 ar
= mp_mul(MP_NEW
, a
, r
);
74 ar
= mp_add(ar
, ar
, m
);
75 ar
= mpbarrett_reduce(&qb
, ar
, ar
);
76 ar
= mp_mul(ar
, ar
, k1
);
77 ar
= mpbarrett_reduce(&qb
, ar
, ar
);
78 mpbarrett_destroy(&qb
);
80 if (*rr
) MP_DROP(*rr
);
81 if (*ss
) MP_DROP(*ss
);
86 /* --- @dsa_sign@ --- *
88 * Arguments: @dsa_param *dp@ = pointer to DSA parameters
89 * @mp *a@ = pointer to secret signing key
90 * @const void *m@ = pointer to message
91 * @size_t msz@ = size of the message
92 * @const void *k@ = secret random data for securing signature
93 * @size_t ksz@ = size of secret data
94 * @void *r@ = pointer to output space for @r@
95 * @size_t rsz@ = size of output space for @r@
96 * @void *s@ = pointer to output space for @s@
97 * @size_t ssz@ = size of output space for @s@
101 * Use: Signs a message, storing the results in a big-endian binary
105 void dsa_sign(dsa_param
*dp
, mp
*a
,
106 const void *m
, size_t msz
, const void *k
, size_t ksz
,
107 void *r
, size_t rsz
, void *s
, size_t ssz
)
109 mp
*mm
= dsa_h2n(MP_NEW
, dp
->q
, m
, msz
);
110 mp
*km
= mp_loadb(MP_NEW
, k
, ksz
);
111 mp
*rm
= MP_NEW
, *sm
= MP_NEW
;
112 dsa_mksig(dp
, a
, mm
, km
, &rm
, &sm
);
113 mp_storeb(rm
, r
, rsz
);
114 mp_storeb(sm
, s
, ssz
);
115 mp_drop(mm
); mp_drop(km
);
116 mp_drop(rm
); mp_drop(sm
);
119 /*----- Test rig ----------------------------------------------------------*/
123 #include <mLib/testrig.h>
127 static int verify(dstr
*v
)
132 octet hash
[SHA_HASHSZ
];
136 dp
.q
= *(mp
**)v
[0].buf
;
137 dp
.p
= *(mp
**)v
[1].buf
;
138 dp
.g
= *(mp
**)v
[2].buf
;
139 x
= *(mp
**)v
[3].buf
;
142 sha_hash(&c
, v
[4].buf
, v
[4].len
);
145 dsa_sign(&dp
, x
, hash
, sizeof(hash
), v
[5].buf
, v
[5].len
,
146 s
.r
, sizeof(s
.r
), s
.s
, sizeof(s
.s
));
148 if (v
[6].len
!= sizeof(s
.r
) || v
[7].len
!= sizeof(s
.s
) ||
149 memcmp(s
.r
, v
[6].buf
, sizeof(s
.r
)) != 0 ||
150 memcmp(s
.s
, v
[7].buf
, sizeof(s
.s
)) != 0) {
151 fputs("\n*** signature failed", stderr
);
152 fputs("\nq = ", stderr
); mp_writefile(dp
.q
, stderr
, 16);
153 fputs("\np = ", stderr
); mp_writefile(dp
.p
, stderr
, 16);
154 fputs("\ng = ", stderr
); mp_writefile(dp
.g
, stderr
, 16);
155 fputs("\nx = ", stderr
); mp_writefile(x
, stderr
, 16);
156 fprintf(stderr
, "\nmessage = `%s'", v
[4].buf
);
157 fputs("\nk = ", stderr
); type_hex
.dump(&v
[5], stderr
);
158 fputs("\nR = ", stderr
); type_hex
.dump(&v
[6], stderr
);
159 fputs("\nS = ", stderr
); type_hex
.dump(&v
[7], stderr
);
163 m
= mp_loadb(m
, hash
, sizeof(hash
));
164 fputs("\nm = ", stderr
); mp_writefile(m
, stderr
, 16);
165 m
= mp_loadb(m
, s
.r
, sizeof(s
.r
));
166 fputs("\nr = ", stderr
); mp_writefile(m
, stderr
, 16);
167 m
= mp_loadb(m
, s
.s
, sizeof(s
.s
));
168 fputs("\ns = ", stderr
); mp_writefile(m
, stderr
, 16);
180 assert(mparena_count(MPARENA_GLOBAL
) == 0);
184 static test_chunk tests
[] = {
186 { &type_mp
, &type_mp
, &type_mp
, &type_mp
,
187 &type_string
, &type_hex
, &type_hex
, &type_hex
, 0 } },
191 int main(int argc
, char *argv
[])
194 test_run(argc
, argv
, tests
, SRCDIR
"/tests/dsa");
200 /*----- That's all, folks -------------------------------------------------*/