3 * Generalized version of KCDSA
5 * (c) 2004 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
33 #include "mpbarrett.h"
36 /*----- Main code ---------------------------------------------------------*/
38 /* --- @gkcdsa_beginhash@ --- *
40 * Arguments: @const gkcdsa *c@ = pointer to the context structure
42 * Returns: A hashing context for you to hash the message.
44 * Use: Initializes a hash function correctly for you to hash a
45 * message. Requires @h@, @g@ and @p@.
48 ghash
*gkcdsa_beginhash(const gkcdsa
*c
)
50 ghash
*h
= GH_INIT(c
->h
);
51 mp
*v
= G_TOINT(c
->g
, MP_NEW
, c
->p
);
52 size_t sz
= c
->h
->bufsz
;
53 void *p
= xmalloc(sz
);
54 if (/*ouch*/ !v
) memset(p
, 0, sz
);
55 else mp_storeb(v
, p
, sz
);
61 /* --- @gkcdsa_endhash@ --- *
63 * Arguments: @const gkcdsa *c@ = pointer to the context structure
64 * @ghash *h@ = the hashing context
68 * Use: Does any final thing that KCDSA wants to do when hashing a
69 * message. (Actually, there's nothing.) The hashing context
73 void gkcdsa_endhash(const gkcdsa
*c
, ghash
*h
) { ; }
77 * Arguments: @group *g@ = abstract group
78 * @const gchash *hc@ = hash class
79 * @ge *w@ = a group element
81 * Returns: A hash context, with the hash of @w@ in it.
84 static ghash
*hashge(group
*g
, const gchash
*hc
, ge
*w
)
97 rc
= G_TORAW(g
, &b
, w
);
100 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
105 /* --- @gkcdsa_sign@ --- *
107 * Arguments: @const gkcdsa *c@ = my context structure
108 * @gkcdsa_sig *s@ = where to put the signature (initialized)
109 * @const void *m@ = pointer to message hash
110 * @mp *k@ = random exponent for this message or null
114 * Use: Signs a message. Requires @g@, @u@, @h@, and @r@ if @k@ is
115 * null. This is a better idea than inventing @k@ yourself.
118 void gkcdsa_sign(const gkcdsa
*c
, gkcdsa_sig
*s
, const void *m
, mp
*k
)
123 size_t hsz
= c
->h
->hashsz
;
126 if (k
) { MP_COPY(k
); goto have_k
; }
128 k
= mprand_range(k
, g
->r
, c
->r
, 0);
130 if (MP_ZEROP(k
)) goto new_k
;
131 G_EXP(g
, z
, g
->g
, k
);
132 if (!s
->r
) s
->r
= xmalloc(hsz
);
133 h
= hashge(g
, c
->h
, z
); GH_DONE(h
, s
->r
);
135 x
= mp_loadb(s
->s
, m
, hsz
);
136 y
= mp_loadb(MP_NEW
, s
->r
, hsz
);
138 mp_div(0, &x
, x
, g
->r
);
139 x
= mp_sub(x
, g
->r
, x
);
141 if (MP_CMP(x
, >=, g
->r
)) x
= mp_sub(x
, x
, g
->r
);
142 x
= mp_mul(x
, x
, c
->u
); mp_div(0, &x
, x
, g
->r
);
144 mp_drop(k
); mp_drop(y
); GH_DESTROY(h
); G_DESTROY(g
, z
);
147 /* --- @gkcdsa_verify@ --- *
149 * Arguments: @const gkcdsa *c@ = my context structure
150 * @const gkcdsa_sig *s@ = the signature to verify
151 * @const void *m@ = pointer to message hash
153 * Returns: Zero if OK, negative on failure.
155 * Use: Checks a signature on a message, Requires @g@, @p@, @h@.
158 int gkcdsa_verify(const gkcdsa
*c
, const gkcdsa_sig
*s
, const void *m
)
161 size_t hsz
= c
->h
->hashsz
;
162 group_expfactor e
[2];
169 if (MP_CMP(s
->s
, <, MP_ONE
) || MP_CMP(s
->s
, >=, g
->r
))
171 x
= mp_loadb(MP_NEW
, m
, hsz
); y
= mp_loadb(MP_NEW
, s
->r
, hsz
);
172 x
= mp_xor(x
, x
, y
); mp_div(0, &x
, x
, g
->r
);
173 e
[0].base
= c
->p
; e
[0].exp
= s
->s
;
174 e
[1].base
= g
->g
; e
[1].exp
= x
;
175 z
= G_CREATE(g
); G_MEXP(g
, z
, e
, 2);
176 h
= hashge(g
, c
->h
, z
); p
= GH_DONE(h
, 0);
177 if (memcmp(p
, s
->r
, hsz
) == 0) rc
= 0;
178 mp_drop(x
); mp_drop(y
); G_DESTROY(g
, z
); GH_DESTROY(h
);
182 /*----- Test rig ----------------------------------------------------------*/
186 static group
*getgroup(const char *p
) {
187 group
*g
; qd_parse qd
;
188 qd
.p
= p
; qd
.e
= 0; g
= group_parse(&qd
);
189 if (g
&& !qd_eofp(&qd
)) { G_DESTROYGROUP(g
); g
= 0; qd
.e
= "junk at eof"; }
191 fprintf(stderr
, "bad group string `%.*s|%s': %s\n",
192 (int)(qd
.p
- p
), p
, qd
.p
, qd
.e
);
198 static ge
*getge(group
*g
, const char *p
) {
200 if (group_readstring(g
, x
, p
, 0)) {
201 fprintf(stderr
, "bad group element `%s'\n", p
);
207 static void showge(group
*g
, const char *p
, ge
*x
) {
208 fprintf(stderr
, "*** %s = ", p
); group_writefile(g
, x
, stderr
);
212 static void showmp(const char *p
, mp
*x
, int r
) {
213 fprintf(stderr
, "*** %s = ", p
); mp_writefile(x
, stderr
, r
);
217 static int tsign(dstr
*v
)
220 gkcdsa_sig s
, ss
= GKCDSA_SIG_INIT
;
227 c
.g
= getgroup(v
[0].buf
); c
.h
= ghash_byname(v
[1].buf
);
228 c
.u
= *(mp
**)v
[2].buf
; k
= *(mp
**)v
[4].buf
;
229 s
.r
= (octet
*)v
[5].buf
; s
.s
= *(mp
**)v
[6].buf
;
230 DENSURE(&d
, c
.h
->hashsz
); d
.len
= c
.h
->hashsz
; memset(d
.buf
, 0, d
.len
);
231 ss
.r
= (octet
*)d
.buf
;
233 x
= mp_modinv(MP_NEW
, c
.u
, c
.g
->r
);
234 c
.p
= G_CREATE(c
.g
); G_EXP(c
.g
, c
.p
, c
.g
->g
, x
);
235 h
= gkcdsa_beginhash(&c
);
236 GH_HASH(h
, v
[3].buf
, v
[3].len
);
237 gkcdsa_endhash(&c
, h
);
238 gkcdsa_sign(&c
, &ss
, GH_DONE(h
, 0), k
);
239 if (memcmp(s
.r
, ss
.r
, c
.h
->hashsz
) || !MP_EQ(s
.s
, ss
.s
)) {
241 fprintf(stderr
, "*** sign failed!\n");
242 fprintf(stderr
, "*** group: %s\n", v
[0].buf
);
243 fprintf(stderr
, "*** hash: %s\n", c
.h
->name
);
244 showmp("private key", c
.u
, 16);
245 showge(c
.g
, "public key", c
.p
);
246 fprintf(stderr
, "*** message: `%s'\n", v
[3].buf
);
247 fprintf(stderr
, "*** computed r = ");
248 type_hex
.dump(&d
, stderr
); putc('\n', stderr
);
249 showmp("computed s", ss
.s
, 16);
250 fprintf(stderr
, "*** computed r = ");
251 type_hex
.dump(&v
[5], stderr
); putc('\n', stderr
);
252 showmp("expected s", s
.s
, 16);
254 mp_drop(s
.s
); dstr_destroy(&d
); mp_drop(ss
.s
); mp_drop(x
); mp_drop(k
);
255 mp_drop(c
.u
); G_DESTROY(c
.g
, c
.p
); G_DESTROYGROUP(c
.g
); GH_DESTROY(h
);
256 assert(mparena_count(MPARENA_GLOBAL
) == 0);
260 static int tverify(dstr
*v
)
268 c
.g
= getgroup(v
[0].buf
); c
.h
= ghash_byname(v
[1].buf
);
269 c
.p
= getge(c
.g
, v
[2].buf
);
270 s
.r
= (octet
*)v
[4].buf
; s
.s
= *(mp
**)v
[5].buf
;
271 erc
= *(int *)v
[6].buf
;
273 h
= gkcdsa_beginhash(&c
);
274 GH_HASH(h
, v
[3].buf
, v
[3].len
);
275 gkcdsa_endhash(&c
, h
);
276 rc
= gkcdsa_verify(&c
, &s
, GH_DONE(h
, 0));
279 fprintf(stderr
, "*** verify failed!\n");
280 fprintf(stderr
, "*** group: %s\n", v
[0].buf
);
281 fprintf(stderr
, "*** hash: %s\n", c
.h
->name
);
282 showge(c
.g
, "public key", c
.p
);
283 fprintf(stderr
, "*** message: `%s'\n", v
[3].buf
);
284 fprintf(stderr
, "*** sig r = ");
285 type_hex
.dump(&v
[4], stderr
); putc('\n', stderr
);
286 showmp("sig s", s
.s
, 16);
287 fprintf(stderr
, "*** expected %s\n", !erc ?
"pass" : "fail");
289 mp_drop(s
.s
); G_DESTROY(c
.g
, c
.p
); G_DESTROYGROUP(c
.g
);
291 assert(mparena_count(MPARENA_GLOBAL
) == 0);
295 static const test_chunk tests
[] = {
296 { "sign", tsign
, { &type_string
, &type_string
, &type_mp
, &type_string
,
297 &type_mp
, &type_hex
, &type_mp
} },
298 { "verify", tverify
, { &type_string
, &type_string
, &type_string
,
299 &type_string
, &type_hex
, &type_mp
, &type_int
} },
303 int main(int argc
, char *argv
[])
306 test_run(argc
, argv
, tests
, SRCDIR
"/t/gkcdsa");
312 /*----- That's all, folks -------------------------------------------------*/