3 * $Id: gkcdsa.c,v 1.2 2004/04/08 01:36:15 mdw Exp $
5 * Generalized version of KCDSA
7 * (c) 2004 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 ------------------------------------------------------*/
35 #include "mpbarrett.h"
38 /*----- Main code ---------------------------------------------------------*/
40 /* --- @gdsa_beginhash@ --- *
42 * Arguments: @const gdsa *c@ = pointer to the context structure
44 * Returns: A hashing context for you to hash the message.
46 * Use: Initializes a hash function correctly for you to hash a
47 * message. Requires @h@, @g@ and @p@.
50 ghash
*gkcdsa_beginhash(const gkcdsa
*c
)
52 ghash
*h
= GH_INIT(c
->h
);
53 mp
*v
= G_TOINT(c
->g
, MP_NEW
, c
->p
);
54 size_t sz
= c
->h
->bufsz
;
55 void *p
= xmalloc(sz
);
56 if (/*ouch*/ !v
) memset(p
, 0, sz
);
57 else mp_storeb(v
, p
, sz
);
63 /* --- @gkcdsa_endhash@ --- *
65 * Arguments: @const gkcdsa *c@ = pointer to the context structure
66 * @ghash *h@ = the hashing context
70 * Use: Does any final thing that KCDSA wants to do when hashing a
71 * message. (Actually, there's nothing.) The hashing context
75 void gkcdsa_endhash(gkcdsa
*c
, ghash
*h
) { ; }
79 * Arguments: @group *g@ = abstract group
80 * @const gchash *hc@ = hash class
81 * @ge *w@ = a group element
83 * Returns: A hash context, with the hash of @w@ in it.
86 static ghash
*hashge(group
*g
, const gchash
*hc
, ge
*w
)
99 rc
= G_TORAW(g
, &b
, w
);
102 GH_HASH(h
, BBASE(&b
), BLEN(&b
));
107 /* --- @gkcdsa_sign@ --- *
109 * Arguments: @const gkcdsa *c@ = my context structure
110 * @gkcdsa_sig *s@ = where to put the signature (initialized)
111 * @const void *m@ = pointer to message hash
112 * @mp *k@ = random exponent for this message or null
116 * Use: Signs a message. Requires @g@, @u@, @h@, and @r@ if @k@ is
117 * null. This is a better idea than inventing @k@ yourself.
120 void gkcdsa_sign(const gkcdsa
*c
, gkcdsa_sig
*s
, const void *m
, mp
*k
)
125 size_t hsz
= c
->h
->hashsz
;
128 if (k
) { MP_COPY(k
); goto have_k
; }
130 k
= mprand_range(k
, g
->r
, c
->r
, 0);
132 if (MP_ISZERO(k
)) goto new_k
;
133 G_EXP(g
, z
, g
->g
, k
);
134 if (!s
->r
) s
->r
= xmalloc(hsz
);
135 h
= hashge(g
, c
->h
, z
); GH_DONE(h
, s
->r
);
137 x
= mp_loadb(s
->s
, m
, hsz
);
138 y
= mp_loadb(MP_NEW
, s
->r
, hsz
);
140 mp_div(0, &x
, x
, g
->r
);
141 x
= mp_sub(x
, g
->r
, x
);
143 if (MP_CMP(x
, >=, g
->r
)) x
= mp_sub(x
, x
, g
->r
);
144 x
= mp_mul(x
, x
, c
->u
); mp_div(0, &x
, x
, g
->r
);
146 mp_drop(k
); mp_drop(y
); GH_DESTROY(h
); G_DESTROY(g
, z
);
149 /* --- @gkcdsa_verify@ --- *
151 * Arguments: @const gkcdsa *c@ = my context structure
152 * @const gkcdsa_sig *s@ = the signature to verify
153 * @const void *m@ = pointer to message hash
155 * Returns: Zero if OK, negative on failure.
157 * Use: Checks a signature on a message, Requires @g@, @p@, @h@.
160 int gkcdsa_verify(const gkcdsa
*c
, const gkcdsa_sig
*s
, const void *m
)
163 size_t hsz
= c
->h
->hashsz
;
164 group_expfactor e
[2];
171 if (MP_CMP(s
->s
, <, MP_ONE
) || MP_CMP(s
->s
, >=, g
->r
))
173 x
= mp_loadb(MP_NEW
, m
, hsz
); y
= mp_loadb(MP_NEW
, s
->r
, hsz
);
174 x
= mp_xor(x
, x
, y
); mp_div(0, &x
, x
, g
->r
);
175 e
[0].base
= c
->p
; e
[0].exp
= s
->s
;
176 e
[1].base
= g
->g
; e
[1].exp
= x
;
177 z
= G_CREATE(g
); G_MEXP(g
, z
, e
, 2);
178 h
= hashge(g
, c
->h
, z
); p
= GH_DONE(h
, 0);
179 if (memcmp(p
, s
->r
, hsz
) == 0) rc
= 0;
180 mp_drop(x
); mp_drop(y
); G_DESTROY(g
, z
); GH_DESTROY(h
);
184 /*----- Test rig ----------------------------------------------------------*/
188 static group
*getgroup(const char *p
) {
189 group
*g
; qd_parse qd
;
190 qd
.p
= p
; qd
.e
= 0; g
= group_parse(&qd
);
191 if (g
&& !qd_eofp(&qd
)) { G_DESTROYGROUP(g
); g
= 0; qd
.e
= "junk at eof"; }
192 if (!g
) { fprintf(stderr
, "bad group string `%.*s|%s': %s\n", qd
.p
- p
,
193 p
, qd
.p
, qd
.e
); exit(1); }
197 static ge
*getge(group
*g
, const char *p
) {
199 if (group_readstring(g
, x
, p
, 0)) {
200 fprintf(stderr
, "bad group element `%s'\n", p
);
206 static void showge(group
*g
, const char *p
, ge
*x
) {
207 fprintf(stderr
, "*** %s = ", p
); group_writefile(g
, x
, stderr
);
211 static void showmp(const char *p
, mp
*x
, int r
) {
212 fprintf(stderr
, "*** %s = ", p
); mp_writefile(x
, stderr
, r
);
216 static int tsign(dstr
*v
)
219 gkcdsa_sig s
, ss
= GKCDSA_SIG_INIT
;
226 c
.g
= getgroup(v
[0].buf
); c
.h
= ghash_byname(v
[1].buf
);
227 c
.u
= *(mp
**)v
[2].buf
; k
= *(mp
**)v
[4].buf
;
228 s
.r
= (octet
*)v
[5].buf
; s
.s
= *(mp
**)v
[6].buf
;
229 DENSURE(&d
, c
.h
->hashsz
); d
.len
= c
.h
->hashsz
; memset(d
.buf
, 0, d
.len
);
230 ss
.r
= (octet
*)d
.buf
;
232 x
= mp_modinv(MP_NEW
, c
.u
, c
.g
->r
);
233 c
.p
= G_CREATE(c
.g
); G_EXP(c
.g
, c
.p
, c
.g
->g
, x
);
234 h
= gkcdsa_beginhash(&c
);
235 GH_HASH(h
, v
[3].buf
, v
[3].len
);
236 gkcdsa_endhash(&c
, h
);
237 gkcdsa_sign(&c
, &ss
, GH_DONE(h
, 0), k
);
238 if (memcmp(s
.r
, ss
.r
, c
.h
->hashsz
) || !MP_EQ(s
.s
, ss
.s
)) {
240 fprintf(stderr
, "*** sign failed!\n");
241 fprintf(stderr
, "*** group: %s\n", v
[0].buf
);
242 fprintf(stderr
, "*** hash: %s\n", c
.h
->name
);
243 showmp("private key", c
.u
, 16);
244 showge(c
.g
, "public key", c
.p
);
245 fprintf(stderr
, "*** message: `%s'\n", v
[3].buf
);
246 fprintf(stderr
, "*** computed r = ");
247 type_hex
.dump(&d
, stderr
); putc('\n', stderr
);
248 showmp("computed s", ss
.s
, 16);
249 fprintf(stderr
, "*** computed r = ");
250 type_hex
.dump(&v
[5], stderr
); putc('\n', stderr
);
251 showmp("expected s", s
.s
, 16);
253 mp_drop(s
.s
); dstr_destroy(&d
); mp_drop(ss
.s
); mp_drop(x
); mp_drop(k
);
254 mp_drop(c
.u
); G_DESTROY(c
.g
, c
.p
); G_DESTROYGROUP(c
.g
); GH_DESTROY(h
);
255 assert(mparena_count(MPARENA_GLOBAL
) == 0);
259 static int tverify(dstr
*v
)
267 c
.g
= getgroup(v
[0].buf
); c
.h
= ghash_byname(v
[1].buf
);
268 c
.p
= getge(c
.g
, v
[2].buf
);
269 s
.r
= (octet
*)v
[4].buf
; s
.s
= *(mp
**)v
[5].buf
;
270 erc
= *(int *)v
[6].buf
;
272 h
= gkcdsa_beginhash(&c
);
273 GH_HASH(h
, v
[3].buf
, v
[3].len
);
274 gkcdsa_endhash(&c
, h
);
275 rc
= gkcdsa_verify(&c
, &s
, GH_DONE(h
, 0));
278 fprintf(stderr
, "*** verify failed!\n");
279 fprintf(stderr
, "*** group: %s\n", v
[0].buf
);
280 fprintf(stderr
, "*** hash: %s\n", c
.h
->name
);
281 showge(c
.g
, "public key", c
.p
);
282 fprintf(stderr
, "*** message: `%s'\n", v
[3].buf
);
283 fprintf(stderr
, "*** sig r = ");
284 type_hex
.dump(&v
[4], stderr
); putc('\n', stderr
);
285 showmp("sig s", s
.s
, 16);
286 fprintf(stderr
, "*** expected %s\n", !erc ?
"pass" : "fail");
288 mp_drop(s
.s
); G_DESTROY(c
.g
, c
.p
); G_DESTROYGROUP(c
.g
);
290 assert(mparena_count(MPARENA_GLOBAL
) == 0);
294 static const test_chunk tests
[] = {
295 { "sign", tsign
, { &type_string
, &type_string
, &type_mp
, &type_string
,
296 &type_mp
, &type_hex
, &type_mp
} },
297 { "verify", tverify
, { &type_string
, &type_string
, &type_string
,
298 &type_string
, &type_hex
, &type_mp
, &type_int
} },
302 int main(int argc
, char *argv
[])
305 test_run(argc
, argv
, tests
, SRCDIR
"/tests/gkcdsa");
311 /*----- That's all, folks -------------------------------------------------*/