3 * $Id: dsa-gen.c,v 1.5 2000/02/12 18:21:02 mdw Exp $
5 * Generate DSA shared parameters
7 * (c) 1999 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 /*----- Revision history --------------------------------------------------*
33 * Revision 1.5 2000/02/12 18:21:02 mdw
34 * Overhaul of key management (again).
36 * Revision 1.4 1999/12/22 15:52:44 mdw
37 * Reworking for new prime-search system.
39 * Revision 1.3 1999/12/10 23:18:38 mdw
40 * Change interface for suggested destinations.
42 * Revision 1.2 1999/11/20 22:23:48 mdw
43 * Allow event handler to abort the search process.
45 * Revision 1.1 1999/11/19 19:28:00 mdw
46 * Implementation of the Digital Signature Algorithm.
50 /*----- Header files ------------------------------------------------------*/
62 #include "primorial.h"
65 /*----- The DSA stepper ---------------------------------------------------*/
69 * Arguments: @pgen_event *ev@ = pointer to event block
70 * @dsa_stepctx *d@ = pointer to stepping context
72 * Returns: A @PGEN@ result code.
74 * Use: Steps the generator once, reads the result, and tests it.
77 static int next(pgen_event *ev, dsa_stepctx *d)
82 /* --- Load the new candidate --- */
84 m = mprand(ev->m, d->bits, d->r, d->or);
86 /* --- Force to be a multiple of @q@ --- */
90 mp_div(0, &r, m, d->q);
97 /* --- Do the trial division --- */
101 mp_gcd(&g, 0, 0, m, primorial);
102 if (MP_CMP(g, ==, MP_ONE) || MP_CMP(g, ==, m))
109 /* --- Return the result --- */
114 /* --- @dsa_step@ --- */
116 int dsa_step(int rq, pgen_event *ev, void *p)
124 return (next(ev, d));
131 /*----- Glue code ---------------------------------------------------------*/
133 /* --- @dsa_seed@ --- *
135 * Arguments: @dsa_param *dp@ = where to store parameters
136 * @unsigned ql@ = length of @q@ in bits
137 * @unsigned pl@ = length of @p@ in bits
138 * @unsigned steps@ = number of steps to find @q@
139 * @const void *k@ = pointer to key material
140 * @size_t sz@ = size of key material
141 * @pgen_proc *event@ = event handler function
142 * @void *ectx@ = argument for event handler
144 * Returns: @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise.
146 * Use: Generates the DSA shared parameters from a given seed value.
148 * The parameters are a prime %$q$%, relatively small, and a
149 * large prime %$p = kq + 1$% for some %$k$%, together with a
150 * generator %$g$% of the cyclic subgroup of order %$q$%. These
151 * are actually the same as the Diffie-Hellman parameter set,
152 * but the generation algorithm is different.
154 * The algorithm used is a compatible extension of the method
155 * described in the DSA standard, FIPS 186. The standard
156 * requires that %$q$% be 160 bits in size (i.e., @ql == 160@)
157 * and that the length of %$p$% be %$L = 512 + 64l$% for some
158 * %$l$%. Neither limitation applies to this implementation.
161 int dsa_seed(dsa_param *dp, unsigned ql, unsigned pl, unsigned steps,
162 const void *k, size_t sz, pgen_proc *event, void *ectx)
170 /* --- Initialize the stepping context --- */
172 s.r = dsarand_create(k, sz);
175 /* --- Find @q@ --- */
178 s.r->ops->misc(s.r, DSARAND_PASSES, 2);
180 if ((dp->q = pgen("q", MP_NEW, MP_NEW, event, ectx, steps, dsa_step, &s,
181 rabin_iters(ql), pgen_test, &r)) == 0)
184 /* --- Find @p@ --- */
186 s.q = mp_lsl(MP_NEW, dp->q, 1);
187 s.r->ops->misc(s.r, DSARAND_PASSES, 1);
189 if ((dp->p = pgen("p", MP_NEW, MP_NEW, event, ectx, 4096, dsa_step, &s,
190 rabin_iters(pl), pgen_test, &r)) == 0)
194 /* --- Find @g@ --- *
196 * The division returns remainder 1. This doesn't matter.
199 mpmont_create(&p.mm, dp->p);
200 qc = MP_NEW; mp_div(&qc, 0, dp->p, dp->q);
204 if ((dp->g = pgen("g", MP_NEW, MP_NEW, event, ectx, 0, prim_step, &i,
205 1, prim_test, &p)) == 0)
211 mpmont_destroy(&p.mm);
212 s.r->ops->destroy(s.r);
215 /* --- Tidy up when things go wrong --- */
219 mpmont_destroy(&p.mm);
224 s.r->ops->destroy(s.r);
228 /*----- Test rig ----------------------------------------------------------*/
232 static int verify(dstr *v)
234 mp *q = *(mp **)v[2].buf;
235 mp *p = *(mp **)v[3].buf;
236 mp *g = *(mp **)v[4].buf;
238 unsigned l = *(unsigned *)v[1].buf;
242 rc = dsa_seed(&dp, 160, l, 1, v[0].buf, v[0].len, pgen_evspin, 0);
243 if (rc || MP_CMP(q, !=, dp.q) ||
244 MP_CMP(p, !=, dp.p) || MP_CMP(g, !=, dp.g)) {
245 fputs("\n*** gen failed", stderr);
246 fputs("\nseed = ", stderr); type_hex.dump(&v[0], stderr);
247 fprintf(stderr, "\nl = %u", l);
248 fputs("\n q = ", stderr); mp_writefile(q, stderr, 16);
249 fputs("\n p = ", stderr); mp_writefile(p, stderr, 16);
250 fputs("\n g = ", stderr); mp_writefile(g, stderr, 16);
252 fputs("\ndp.q = ", stderr); mp_writefile(dp.q, stderr, 16);
253 fputs("\ndp.p = ", stderr); mp_writefile(dp.p, stderr, 16);
254 fputs("\ndp.g = ", stderr); mp_writefile(dp.g, stderr, 16);
260 mp_drop(q); mp_drop(p); mp_drop(g);
262 mp_drop(dp.q); mp_drop(dp.p); mp_drop(dp.g);
264 assert(mparena_count(MPARENA_GLOBAL) == 1); /* Primorial! */
268 static test_chunk tests[] = {
270 { &type_hex, &type_int, &type_mp, &type_mp, &type_mp, 0 } },
274 int main(int argc, char *argv[])
277 test_run(argc, argv, tests, SRCDIR "/tests/dsa");
283 /*----- That's all, folks -------------------------------------------------*/