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1 | /* -*-c-*- |
2 | * |
2b31b269 |
3 | * $Id: dsa-gen.c,v 1.6 2000/07/29 10:00:14 mdw Exp $ |
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4 | * |
5 | * Generate DSA shared parameters |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
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. |
18 | * |
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. |
23 | * |
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, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: dsa-gen.c,v $ |
2b31b269 |
33 | * Revision 1.6 2000/07/29 10:00:14 mdw |
34 | * Rename `dsa_seed' to `dsa_gen' for consistency with other parameter- |
35 | * generation interfaces. |
36 | * |
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37 | * Revision 1.5 2000/02/12 18:21:02 mdw |
38 | * Overhaul of key management (again). |
39 | * |
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40 | * Revision 1.4 1999/12/22 15:52:44 mdw |
41 | * Reworking for new prime-search system. |
42 | * |
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43 | * Revision 1.3 1999/12/10 23:18:38 mdw |
44 | * Change interface for suggested destinations. |
45 | * |
987bb691 |
46 | * Revision 1.2 1999/11/20 22:23:48 mdw |
47 | * Allow event handler to abort the search process. |
48 | * |
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49 | * Revision 1.1 1999/11/19 19:28:00 mdw |
50 | * Implementation of the Digital Signature Algorithm. |
51 | * |
52 | */ |
53 | |
54 | /*----- Header files ------------------------------------------------------*/ |
55 | |
56 | #include <stdio.h> |
57 | #include <stdlib.h> |
58 | |
59 | #include "dsa.h" |
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60 | #include "dsarand.h" |
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61 | #include "fibrand.h" |
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62 | #include "mp.h" |
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63 | #include "mprand.h" |
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64 | #include "pgen.h" |
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65 | #include "prim.h" |
66 | #include "primorial.h" |
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67 | #include "sha.h" |
68 | |
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69 | /*----- The DSA stepper ---------------------------------------------------*/ |
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70 | |
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71 | /* --- @next@ --- * |
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72 | * |
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73 | * Arguments: @pgen_event *ev@ = pointer to event block |
74 | * @dsa_stepctx *d@ = pointer to stepping context |
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75 | * |
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76 | * Returns: A @PGEN@ result code. |
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77 | * |
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78 | * Use: Steps the generator once, reads the result, and tests it. |
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79 | */ |
80 | |
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81 | static int next(pgen_event *ev, dsa_stepctx *d) |
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82 | { |
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83 | mp *m; |
84 | int rc; |
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85 | |
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86 | /* --- Load the new candidate --- */ |
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87 | |
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88 | m = mprand(ev->m, d->bits, d->r, d->or); |
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89 | |
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90 | /* --- Force to be a multiple of @q@ --- */ |
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91 | |
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92 | if (d->q) { |
93 | mp *r = MP_NEW; |
94 | mp_div(0, &r, m, d->q); |
95 | m = mp_sub(m, m, r); |
96 | mp_drop(r); |
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97 | } |
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98 | m->v[0] |= d->or; |
99 | ev->m = m; |
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100 | |
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101 | /* --- Do the trial division --- */ |
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102 | |
103 | { |
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104 | mp *g = MP_NEW; |
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105 | mp_gcd(&g, 0, 0, m, primorial); |
106 | if (MP_CMP(g, ==, MP_ONE) || MP_CMP(g, ==, m)) |
107 | rc = PGEN_TRY; |
108 | else |
109 | rc = PGEN_FAIL; |
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110 | mp_drop(g); |
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111 | } |
112 | |
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113 | /* --- Return the result --- */ |
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114 | |
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115 | return (rc); |
116 | } |
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117 | |
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118 | /* --- @dsa_step@ --- */ |
119 | |
120 | int dsa_step(int rq, pgen_event *ev, void *p) |
121 | { |
122 | dsa_stepctx *d = p; |
123 | |
124 | switch (rq) { |
125 | case PGEN_BEGIN: |
126 | primorial_setup(); |
127 | case PGEN_TRY: |
128 | return (next(ev, d)); |
129 | case PGEN_DONE: |
130 | return (PGEN_DONE); |
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131 | } |
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132 | return (PGEN_ABORT); |
133 | } |
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134 | |
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135 | /*----- Glue code ---------------------------------------------------------*/ |
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136 | |
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137 | /* --- @dsa_gen@ --- * |
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138 | * |
139 | * Arguments: @dsa_param *dp@ = where to store parameters |
140 | * @unsigned ql@ = length of @q@ in bits |
141 | * @unsigned pl@ = length of @p@ in bits |
142 | * @unsigned steps@ = number of steps to find @q@ |
143 | * @const void *k@ = pointer to key material |
144 | * @size_t sz@ = size of key material |
145 | * @pgen_proc *event@ = event handler function |
146 | * @void *ectx@ = argument for event handler |
147 | * |
148 | * Returns: @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise. |
149 | * |
150 | * Use: Generates the DSA shared parameters from a given seed value. |
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151 | * |
152 | * The parameters are a prime %$q$%, relatively small, and a |
153 | * large prime %$p = kq + 1$% for some %$k$%, together with a |
154 | * generator %$g$% of the cyclic subgroup of order %$q$%. These |
155 | * are actually the same as the Diffie-Hellman parameter set, |
156 | * but the generation algorithm is different. |
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157 | * |
158 | * The algorithm used is a compatible extension of the method |
159 | * described in the DSA standard, FIPS 186. The standard |
160 | * requires that %$q$% be 160 bits in size (i.e., @ql == 160@) |
161 | * and that the length of %$p$% be %$L = 512 + 64l$% for some |
162 | * %$l$%. Neither limitation applies to this implementation. |
163 | */ |
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164 | |
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165 | int dsa_gen(dsa_param *dp, unsigned ql, unsigned pl, unsigned steps, |
166 | const void *k, size_t sz, pgen_proc *event, void *ectx) |
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167 | { |
168 | dsa_stepctx s; |
169 | prim_ctx p; |
170 | int i; |
171 | rabin r; |
172 | mp *qc; |
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173 | |
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174 | /* --- Initialize the stepping context --- */ |
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175 | |
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176 | s.r = dsarand_create(k, sz); |
177 | s.or = 1; |
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178 | |
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179 | /* --- Find @q@ --- */ |
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180 | |
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181 | s.q = 0; |
182 | s.r->ops->misc(s.r, DSARAND_PASSES, 2); |
183 | s.bits = ql; |
184 | if ((dp->q = pgen("q", MP_NEW, MP_NEW, event, ectx, steps, dsa_step, &s, |
185 | rabin_iters(ql), pgen_test, &r)) == 0) |
186 | goto fail_q; |
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187 | |
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188 | /* --- Find @p@ --- */ |
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189 | |
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190 | s.q = mp_lsl(MP_NEW, dp->q, 1); |
191 | s.r->ops->misc(s.r, DSARAND_PASSES, 1); |
192 | s.bits = pl; |
193 | if ((dp->p = pgen("p", MP_NEW, MP_NEW, event, ectx, 4096, dsa_step, &s, |
194 | rabin_iters(pl), pgen_test, &r)) == 0) |
195 | goto fail_p; |
196 | mp_drop(s.q); |
197 | |
198 | /* --- Find @g@ --- * |
199 | * |
200 | * The division returns remainder 1. This doesn't matter. |
201 | */ |
202 | |
203 | mpmont_create(&p.mm, dp->p); |
204 | qc = MP_NEW; mp_div(&qc, 0, dp->p, dp->q); |
205 | i = 0; |
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206 | p.exp = qc; |
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207 | p.n = 0; |
208 | if ((dp->g = pgen("g", MP_NEW, MP_NEW, event, ectx, 0, prim_step, &i, |
209 | 1, prim_test, &p)) == 0) |
210 | goto fail_g; |
211 | |
212 | /* --- Done --- */ |
213 | |
214 | mp_drop(qc); |
215 | mpmont_destroy(&p.mm); |
216 | s.r->ops->destroy(s.r); |
217 | return (PGEN_DONE); |
218 | |
219 | /* --- Tidy up when things go wrong --- */ |
220 | |
221 | fail_g: |
222 | mp_drop(qc); |
223 | mpmont_destroy(&p.mm); |
224 | fail_p: |
225 | mp_drop(dp->q); |
226 | mp_drop(s.q); |
227 | fail_q: |
228 | s.r->ops->destroy(s.r); |
229 | return (PGEN_ABORT); |
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230 | } |
231 | |
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232 | /*----- Test rig ----------------------------------------------------------*/ |
233 | |
234 | #ifdef TEST_RIG |
235 | |
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236 | static int verify(dstr *v) |
237 | { |
238 | mp *q = *(mp **)v[2].buf; |
239 | mp *p = *(mp **)v[3].buf; |
240 | mp *g = *(mp **)v[4].buf; |
241 | dsa_param dp; |
242 | unsigned l = *(unsigned *)v[1].buf; |
243 | int ok = 1; |
244 | int rc; |
245 | |
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246 | rc = dsa_gen(&dp, 160, l, 1, v[0].buf, v[0].len, pgen_evspin, 0); |
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247 | if (rc || MP_CMP(q, !=, dp.q) || |
248 | MP_CMP(p, !=, dp.p) || MP_CMP(g, !=, dp.g)) { |
249 | fputs("\n*** gen failed", stderr); |
250 | fputs("\nseed = ", stderr); type_hex.dump(&v[0], stderr); |
251 | fprintf(stderr, "\nl = %u", l); |
252 | fputs("\n q = ", stderr); mp_writefile(q, stderr, 16); |
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253 | fputs("\n p = ", stderr); mp_writefile(p, stderr, 16); |
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254 | fputs("\n g = ", stderr); mp_writefile(g, stderr, 16); |
255 | if (!rc) { |
256 | fputs("\ndp.q = ", stderr); mp_writefile(dp.q, stderr, 16); |
257 | fputs("\ndp.p = ", stderr); mp_writefile(dp.p, stderr, 16); |
258 | fputs("\ndp.g = ", stderr); mp_writefile(dp.g, stderr, 16); |
259 | } |
260 | fputc('\n', stderr); |
261 | ok = 0; |
262 | } |
263 | |
264 | mp_drop(q); mp_drop(p); mp_drop(g); |
265 | if (!rc) { |
266 | mp_drop(dp.q); mp_drop(dp.p); mp_drop(dp.g); |
267 | } |
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268 | assert(mparena_count(MPARENA_GLOBAL) == 1); /* Primorial! */ |
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269 | return (ok); |
270 | } |
271 | |
272 | static test_chunk tests[] = { |
273 | { "gen", verify, |
274 | { &type_hex, &type_int, &type_mp, &type_mp, &type_mp, 0 } }, |
275 | { 0, 0, { 0 } } |
276 | }; |
277 | |
278 | int main(int argc, char *argv[]) |
279 | { |
280 | sub_init(); |
281 | test_run(argc, argv, tests, SRCDIR "/tests/dsa"); |
282 | return (0); |
283 | } |
284 | |
285 | #endif |
286 | |
287 | /*----- That's all, folks -------------------------------------------------*/ |