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e9026a0a | 1 | /* -*-c-*- |
2 | * | |
e9026a0a | 3 | * Generalized version of KCDSA |
4 | * | |
5 | * (c) 2004 Straylight/Edgeware | |
6 | */ | |
7 | ||
45c0fd36 | 8 | /*----- Licensing notice --------------------------------------------------* |
e9026a0a | 9 | * |
10 | * This file is part of Catacomb. | |
11 | * | |
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. | |
45c0fd36 | 16 | * |
e9026a0a | 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. | |
45c0fd36 | 21 | * |
e9026a0a | 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, | |
25 | * MA 02111-1307, USA. | |
26 | */ | |
27 | ||
e9026a0a | 28 | /*----- Header files ------------------------------------------------------*/ |
29 | ||
30 | #include "gkcdsa.h" | |
31 | #include "group.h" | |
32 | #include "ghash.h" | |
33 | #include "mpbarrett.h" | |
34 | #include "mprand.h" | |
35 | ||
36 | /*----- Main code ---------------------------------------------------------*/ | |
37 | ||
f4535c64 | 38 | /* --- @gkcdsa_beginhash@ --- * |
e9026a0a | 39 | * |
f4535c64 | 40 | * Arguments: @const gkcdsa *c@ = pointer to the context structure |
e9026a0a | 41 | * |
42 | * Returns: A hashing context for you to hash the message. | |
43 | * | |
44 | * Use: Initializes a hash function correctly for you to hash a | |
45 | * message. Requires @h@, @g@ and @p@. | |
46 | */ | |
47 | ||
48 | ghash *gkcdsa_beginhash(const gkcdsa *c) | |
49 | { | |
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); | |
e9026a0a | 54 | if (/*ouch*/ !v) memset(p, 0, sz); |
55 | else mp_storeb(v, p, sz); | |
56 | GH_HASH(h, p, sz); | |
57 | mp_drop(v); xfree(p); | |
58 | return (h); | |
59 | } | |
60 | ||
61 | /* --- @gkcdsa_endhash@ --- * | |
62 | * | |
63 | * Arguments: @const gkcdsa *c@ = pointer to the context structure | |
64 | * @ghash *h@ = the hashing context | |
65 | * | |
66 | * Returns: --- | |
67 | * | |
68 | * Use: Does any final thing that KCDSA wants to do when hashing a | |
45c0fd36 | 69 | * message. (Actually, there's nothing.) The hashing context |
e9026a0a | 70 | * isn't finalized. |
71 | */ | |
72 | ||
f4535c64 | 73 | void gkcdsa_endhash(const gkcdsa *c, ghash *h) { ; } |
e9026a0a | 74 | |
75 | /* --- @hashge@ --- * | |
76 | * | |
77 | * Arguments: @group *g@ = abstract group | |
78 | * @const gchash *hc@ = hash class | |
79 | * @ge *w@ = a group element | |
80 | * | |
81 | * Returns: A hash context, with the hash of @w@ in it. | |
82 | */ | |
83 | ||
84 | static ghash *hashge(group *g, const gchash *hc, ge *w) | |
85 | { | |
86 | ghash *h; | |
87 | size_t sz; | |
88 | void *p; | |
89 | buf b; | |
90 | int rc; | |
91 | ||
92 | sz = hc->hashsz; | |
93 | if (sz < g->noctets) | |
94 | sz = g->noctets; | |
95 | p = xmalloc(sz); | |
96 | buf_init(&b, p, sz); | |
97 | rc = G_TORAW(g, &b, w); | |
98 | assert(rc == 0); | |
99 | h = GH_INIT(hc); | |
100 | GH_HASH(h, BBASE(&b), BLEN(&b)); | |
101 | xfree(p); | |
102 | return (h); | |
103 | } | |
104 | ||
105 | /* --- @gkcdsa_sign@ --- * | |
106 | * | |
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 | |
111 | * | |
112 | * Returns: --- | |
113 | * | |
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. | |
116 | */ | |
117 | ||
118 | void gkcdsa_sign(const gkcdsa *c, gkcdsa_sig *s, const void *m, mp *k) | |
119 | { | |
120 | group *g = c->g; | |
121 | mp *x, *y; | |
122 | ge *z = G_CREATE(g); | |
123 | size_t hsz = c->h->hashsz; | |
124 | ghash *h; | |
125 | ||
126 | if (k) { MP_COPY(k); goto have_k; } | |
127 | new_k: | |
128 | k = mprand_range(k, g->r, c->r, 0); | |
129 | have_k: | |
a69a3efd | 130 | if (MP_ZEROP(k)) goto new_k; |
e9026a0a | 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); | |
134 | ||
135 | x = mp_loadb(s->s, m, hsz); | |
136 | y = mp_loadb(MP_NEW, s->r, hsz); | |
137 | x = mp_xor(x, x, y); | |
138 | mp_div(0, &x, x, g->r); | |
139 | x = mp_sub(x, g->r, x); | |
140 | x = mp_add(x, x, k); | |
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); | |
143 | s->s = x; | |
144 | mp_drop(k); mp_drop(y); GH_DESTROY(h); G_DESTROY(g, z); | |
145 | } | |
146 | ||
147 | /* --- @gkcdsa_verify@ --- * | |
148 | * | |
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 | |
152 | * | |
153 | * Returns: Zero if OK, negative on failure. | |
154 | * | |
155 | * Use: Checks a signature on a message, Requires @g@, @p@, @h@. | |
156 | */ | |
157 | ||
158 | int gkcdsa_verify(const gkcdsa *c, const gkcdsa_sig *s, const void *m) | |
159 | { | |
160 | group *g = c->g; | |
161 | size_t hsz = c->h->hashsz; | |
162 | group_expfactor e[2]; | |
163 | mp *x, *y; | |
164 | ghash *h; | |
165 | ge *z; | |
166 | octet *p; | |
167 | int rc = -1; | |
168 | ||
169 | if (MP_CMP(s->s, <, MP_ONE) || MP_CMP(s->s, >=, g->r)) | |
170 | return (-1); | |
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); | |
179 | return (rc); | |
180 | } | |
181 | ||
182 | /*----- Test rig ----------------------------------------------------------*/ | |
183 | ||
184 | #ifdef TEST_RIG | |
185 | ||
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"; } | |
bb77b1d1 MW |
190 | if (!g) { |
191 | fprintf(stderr, "bad group string `%.*s|%s': %s\n", | |
192 | (int)(qd.p - p), p, qd.p, qd.e); | |
193 | exit(1); | |
194 | } | |
e9026a0a | 195 | return (g); |
196 | } | |
197 | ||
198 | static ge *getge(group *g, const char *p) { | |
199 | ge *x = G_CREATE(g); | |
200 | if (group_readstring(g, x, p, 0)) { | |
201 | fprintf(stderr, "bad group element `%s'\n", p); | |
202 | exit(1); | |
203 | } | |
204 | return (x); | |
205 | } | |
206 | ||
207 | static void showge(group *g, const char *p, ge *x) { | |
208 | fprintf(stderr, "*** %s = ", p); group_writefile(g, x, stderr); | |
209 | putc('\n', stderr); | |
210 | } | |
211 | ||
212 | static void showmp(const char *p, mp *x, int r) { | |
45c0fd36 | 213 | fprintf(stderr, "*** %s = ", p); mp_writefile(x, stderr, r); |
e9026a0a | 214 | putc('\n', stderr); |
215 | } | |
216 | ||
217 | static int tsign(dstr *v) | |
218 | { | |
219 | gdsa c; | |
220 | gkcdsa_sig s, ss = GKCDSA_SIG_INIT; | |
221 | ghash *h; | |
222 | mp *k; | |
223 | dstr d = DSTR_INIT; | |
224 | mp *x; | |
225 | int ok = 1; | |
226 | ||
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; | |
232 | ||
b817bfc6 | 233 | x = mp_modinv(MP_NEW, c.u, c.g->r); |
e9026a0a | 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)) { | |
240 | ok = 0; | |
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); | |
253 | } | |
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); | |
257 | return (ok); | |
258 | } | |
259 | ||
260 | static int tverify(dstr *v) | |
261 | { | |
262 | gkcdsa c; | |
263 | gkcdsa_sig s; | |
264 | ghash *h; | |
265 | int rc, erc; | |
266 | int ok = 1; | |
267 | ||
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; | |
272 | ||
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)); | |
277 | if (!rc != !erc) { | |
278 | ok = 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"); | |
288 | } | |
289 | mp_drop(s.s); G_DESTROY(c.g, c.p); G_DESTROYGROUP(c.g); | |
290 | GH_DESTROY(h); | |
291 | assert(mparena_count(MPARENA_GLOBAL) == 0); | |
292 | return (ok); | |
293 | } | |
294 | ||
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 } }, | |
300 | { 0 } | |
301 | }; | |
302 | ||
303 | int main(int argc, char *argv[]) | |
304 | { | |
305 | sub_init(); | |
0f00dc4c | 306 | test_run(argc, argv, tests, SRCDIR "/t/gkcdsa"); |
e9026a0a | 307 | return (0); |
308 | } | |
309 | ||
310 | #endif | |
311 | ||
312 | /*----- That's all, folks -------------------------------------------------*/ |