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 ------------------------------------------------------*/
30 #include <mLib/macros.h>
36 #include "mpbarrett.h"
39 /*----- Main code ---------------------------------------------------------*/
41 /* --- @gkcdsa_beginhash@ --- *
43 * Arguments: @const gkcdsa *c@ = pointer to the context structure
45 * Returns: A hashing context for you to hash the message.
47 * Use: Initializes a hash function correctly for you to hash a
48 * message. Requires @h@, @g@ and @p@.
51 ghash
*gkcdsa_beginhash(const gkcdsa
*c
)
53 ghash
*h
= GH_INIT(c
->h
);
54 mp
*v
= G_TOINT(c
->g
, MP_NEW
, c
->p
);
55 size_t sz
= c
->h
->bufsz
;
56 void *p
= xmalloc(sz
);
57 if (/*ouch*/ !v
) memset(p
, 0, sz
);
58 else mp_storeb(v
, p
, sz
);
64 /* --- @gkcdsa_endhash@ --- *
66 * Arguments: @const gkcdsa *c@ = pointer to the context structure
67 * @ghash *h@ = the hashing context
71 * Use: Does any final thing that KCDSA wants to do when hashing a
72 * message. (Actually, there's nothing.) The hashing context
76 void gkcdsa_endhash(const gkcdsa
*c
, ghash
*h
) { ; }
80 * Arguments: @group *g@ = abstract group
81 * @const gchash *hc@ = hash class
82 * @ge *w@ = a group element
84 * Returns: A hash context, with the hash of @w@ in it.
87 static ghash
*hashge(group
*g
, const gchash
*hc
, ge
*w
)
100 rc
= G_TORAW(g
, &b
, w
);
103 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
108 /* --- @gkcdsa_sign@ --- *
110 * Arguments: @const gkcdsa *c@ = my context structure
111 * @gkcdsa_sig *s@ = where to put the signature (initialized)
112 * @const void *m@ = pointer to message hash
113 * @mp *k@ = random exponent for this message or null
117 * Use: Signs a message. Requires @g@, @u@, @h@, and @r@ if @k@ is
118 * null. This is a better idea than inventing @k@ yourself.
121 void gkcdsa_sign(const gkcdsa
*c
, gkcdsa_sig
*s
, const void *m
, mp
*k
)
126 size_t hsz
= c
->h
->hashsz
;
129 if (k
) { MP_COPY(k
); goto have_k
; }
131 k
= dsa_nonce(k
, g
->r
, c
->u
, m
, c
->h
, c
->r
);
133 if (MP_ZEROP(k
)) goto new_k
;
134 G_EXP(g
, z
, g
->g
, k
);
135 if (!s
->r
) s
->r
= xmalloc(hsz
);
136 h
= hashge(g
, c
->h
, z
); GH_DONE(h
, s
->r
);
138 x
= mp_loadb(s
->s
, m
, hsz
);
139 y
= mp_loadb(MP_NEW
, s
->r
, hsz
);
141 mp_div(0, &x
, x
, g
->r
);
142 x
= mp_sub(x
, g
->r
, x
);
144 if (MP_CMP(x
, >=, g
->r
)) x
= mp_sub(x
, x
, g
->r
);
145 x
= mp_mul(x
, x
, c
->u
); mp_div(0, &x
, x
, g
->r
);
147 mp_drop(k
); mp_drop(y
); GH_DESTROY(h
); G_DESTROY(g
, z
);
150 /* --- @gkcdsa_verify@ --- *
152 * Arguments: @const gkcdsa *c@ = my context structure
153 * @const gkcdsa_sig *s@ = the signature to verify
154 * @const void *m@ = pointer to message hash
156 * Returns: Zero if OK, negative on failure.
158 * Use: Checks a signature on a message, Requires @g@, @p@, @h@.
161 int gkcdsa_verify(const gkcdsa
*c
, const gkcdsa_sig
*s
, const void *m
)
164 size_t hsz
= c
->h
->hashsz
;
165 group_expfactor e
[2];
172 if (MP_CMP(s
->s
, <, MP_ONE
) || MP_CMP(s
->s
, >=, g
->r
))
174 x
= mp_loadb(MP_NEW
, m
, hsz
); y
= mp_loadb(MP_NEW
, s
->r
, hsz
);
175 x
= mp_xor(x
, x
, y
); mp_div(0, &x
, x
, g
->r
);
176 e
[0].base
= c
->p
; e
[0].exp
= s
->s
;
177 e
[1].base
= g
->g
; e
[1].exp
= x
;
178 z
= G_CREATE(g
); G_MEXP(g
, z
, e
, 2);
179 h
= hashge(g
, c
->h
, z
); p
= GH_DONE(h
, 0);
180 if (MEMCMP(p
, ==, s
->r
, hsz
)) rc
= 0;
181 mp_drop(x
); mp_drop(y
); G_DESTROY(g
, z
); GH_DESTROY(h
);
185 /*----- Test rig ----------------------------------------------------------*/
191 static group
*getgroup(const char *p
) {
192 group
*g
; qd_parse qd
;
193 qd
.p
= p
; qd
.e
= 0; g
= group_parse(&qd
);
194 if (g
&& !qd_eofp(&qd
)) { G_DESTROYGROUP(g
); g
= 0; qd
.e
= "junk at eof"; }
196 fprintf(stderr
, "bad group string `%.*s|%s': %s\n",
197 (int)(qd
.p
- p
), p
, qd
.p
, qd
.e
);
203 static ge
*getge(group
*g
, const char *p
) {
205 if (group_readstring(g
, x
, p
, 0)) {
206 fprintf(stderr
, "bad group element `%s'\n", p
);
212 static void showge(group
*g
, const char *p
, ge
*x
) {
213 fprintf(stderr
, "*** %s = ", p
); group_writefile(g
, x
, stderr
);
217 static void showmp(const char *p
, mp
*x
, int r
) {
218 fprintf(stderr
, "*** %s = ", p
); mp_writefile(x
, stderr
, r
);
222 static int tsign(dstr
*v
)
225 gkcdsa_sig s
, ss
= GKCDSA_SIG_INIT
;
233 c
.g
= getgroup(v
[0].buf
); c
.h
= ghash_byname(v
[1].buf
);
234 c
.u
= *(mp
**)v
[2].buf
; k
= *(mp
**)v
[4].buf
;
235 s
.r
= (octet
*)v
[5].buf
; s
.s
= *(mp
**)v
[6].buf
;
236 DENSURE(&d
, c
.h
->hashsz
); d
.len
= c
.h
->hashsz
; memset(d
.buf
, 0, d
.len
);
237 ss
.r
= (octet
*)d
.buf
;
239 x
= mp_modinv(MP_NEW
, c
.u
, c
.g
->r
);
240 c
.p
= G_CREATE(c
.g
); G_EXP(c
.g
, c
.p
, c
.g
->g
, x
);
241 h
= gkcdsa_beginhash(&c
);
242 GH_HASH(h
, v
[3].buf
, v
[3].len
);
243 gkcdsa_endhash(&c
, h
);
244 gkcdsa_sign(&c
, &ss
, GH_DONE(h
, 0), k
);
246 if (MEMCMP(s
.r
, !=, ss
.r
, c
.h
->hashsz
) || !MP_EQ(s
.s
, ss
.s
)) {
248 fprintf(stderr
, "*** sign failed!\n");
249 fprintf(stderr
, "*** group: %s\n", v
[0].buf
);
250 fprintf(stderr
, "*** hash: %s\n", c
.h
->name
);
251 showmp("private key", c
.u
, 16);
252 showge(c
.g
, "public key", c
.p
);
253 fprintf(stderr
, "*** message: `%s'\n", v
[3].buf
);
254 fprintf(stderr
, "*** computed r = ");
255 type_hex
.dump(&d
, stderr
); putc('\n', stderr
);
256 showmp("computed s", ss
.s
, 16);
257 fprintf(stderr
, "*** expected r = ");
258 type_hex
.dump(&v
[5], stderr
); putc('\n', stderr
);
259 showmp("expected s", s
.s
, 16);
263 h
= gkcdsa_beginhash(&c
);
264 GH_HASH(h
, v
[3].buf
, v
[3].len
);
267 gkcdsa_sign(&c
, &ss
, m
, 0);
268 if (gkcdsa_verify(&c
, &ss
, m
)) {
270 fprintf(stderr
, "*** sign cross-check failed!\n");
271 fprintf(stderr
, "*** group: %s\n", v
[0].buf
);
272 fprintf(stderr
, "*** hash: %s\n", c
.h
->name
);
273 showmp("private key", c
.u
, 16);
274 showge(c
.g
, "public key", c
.p
);
275 fprintf(stderr
, "*** message: `%s'\n", v
[3].buf
);
276 fprintf(stderr
, "*** computed r = ");
277 type_hex
.dump(&d
, stderr
); putc('\n', stderr
);
278 showmp("computed s", ss
.s
, 16);
281 mp_drop(s
.s
); mp_drop(x
); mp_drop(k
); dstr_destroy(&d
); mp_drop(ss
.s
);
282 mp_drop(c
.u
); G_DESTROY(c
.g
, c
.p
); G_DESTROYGROUP(c
.g
);
283 assert(mparena_count(MPARENA_GLOBAL
) == 0);
287 static int tverify(dstr
*v
)
295 c
.g
= getgroup(v
[0].buf
); c
.h
= ghash_byname(v
[1].buf
);
296 c
.p
= getge(c
.g
, v
[2].buf
);
297 s
.r
= (octet
*)v
[4].buf
; s
.s
= *(mp
**)v
[5].buf
;
298 erc
= *(int *)v
[6].buf
;
300 h
= gkcdsa_beginhash(&c
);
301 GH_HASH(h
, v
[3].buf
, v
[3].len
);
302 gkcdsa_endhash(&c
, h
);
303 rc
= gkcdsa_verify(&c
, &s
, GH_DONE(h
, 0));
306 fprintf(stderr
, "*** verify failed!\n");
307 fprintf(stderr
, "*** group: %s\n", v
[0].buf
);
308 fprintf(stderr
, "*** hash: %s\n", c
.h
->name
);
309 showge(c
.g
, "public key", c
.p
);
310 fprintf(stderr
, "*** message: `%s'\n", v
[3].buf
);
311 fprintf(stderr
, "*** sig r = ");
312 type_hex
.dump(&v
[4], stderr
); putc('\n', stderr
);
313 showmp("sig s", s
.s
, 16);
314 fprintf(stderr
, "*** expected %s\n", !erc ?
"pass" : "fail");
316 mp_drop(s
.s
); G_DESTROY(c
.g
, c
.p
); G_DESTROYGROUP(c
.g
);
318 assert(mparena_count(MPARENA_GLOBAL
) == 0);
322 static const test_chunk tests
[] = {
323 { "sign", tsign
, { &type_string
, &type_string
, &type_mp
, &type_string
,
324 &type_mp
, &type_hex
, &type_mp
} },
325 { "verify", tverify
, { &type_string
, &type_string
, &type_string
,
326 &type_string
, &type_hex
, &type_mp
, &type_int
} },
330 int main(int argc
, char *argv
[])
333 test_run(argc
, argv
, tests
, SRCDIR
"/t/gkcdsa");
339 /*----- That's all, folks -------------------------------------------------*/