3 * $Id: dsa-gen.c,v 1.6 2000/07/29 10:00:14 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 1.6 2000/07/29 10:00:14 mdw
34 * Rename `dsa_seed' to `dsa_gen' for consistency with other parameter-
35 * generation interfaces.
37 * Revision 1.5 2000/02/12 18:21:02 mdw
38 * Overhaul of key management (again).
40 * Revision 1.4 1999/12/22 15:52:44 mdw
41 * Reworking for new prime-search system.
43 * Revision 1.3 1999/12/10 23:18:38 mdw
44 * Change interface for suggested destinations.
46 * Revision 1.2 1999/11/20 22:23:48 mdw
47 * Allow event handler to abort the search process.
49 * Revision 1.1 1999/11/19 19:28:00 mdw
50 * Implementation of the Digital Signature Algorithm.
54 /*----- Header files ------------------------------------------------------*/
66 #include "primorial.h"
69 /*----- The DSA stepper ---------------------------------------------------*/
73 * Arguments: @pgen_event *ev@ = pointer to event block
74 * @dsa_stepctx *d@ = pointer to stepping context
76 * Returns: A @PGEN@ result code.
78 * Use: Steps the generator once, reads the result, and tests it.
81 static int next(pgen_event
*ev
, dsa_stepctx
*d
)
86 /* --- Load the new candidate --- */
88 m
= mprand(ev
->m
, d
->bits
, d
->r
, d
->or);
90 /* --- Force to be a multiple of @q@ --- */
94 mp_div(0, &r
, m
, d
->q
);
101 /* --- Do the trial division --- */
105 mp_gcd(&g
, 0, 0, m
, primorial
);
106 if (MP_CMP(g
, ==, MP_ONE
) || MP_CMP(g
, ==, m
))
113 /* --- Return the result --- */
118 /* --- @dsa_step@ --- */
120 int dsa_step(int rq
, pgen_event
*ev
, void *p
)
128 return (next(ev
, d
));
135 /*----- Glue code ---------------------------------------------------------*/
137 /* --- @dsa_gen@ --- *
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
148 * Returns: @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise.
150 * Use: Generates the DSA shared parameters from a given seed value.
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.
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.
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
)
174 /* --- Initialize the stepping context --- */
176 s
.r
= dsarand_create(k
, sz
);
179 /* --- Find @q@ --- */
182 s
.r
->ops
->misc(s
.r
, DSARAND_PASSES
, 2);
184 if ((dp
->q
= pgen("q", MP_NEW
, MP_NEW
, event
, ectx
, steps
, dsa_step
, &s
,
185 rabin_iters(ql
), pgen_test
, &r
)) == 0)
188 /* --- Find @p@ --- */
190 s
.q
= mp_lsl(MP_NEW
, dp
->q
, 1);
191 s
.r
->ops
->misc(s
.r
, DSARAND_PASSES
, 1);
193 if ((dp
->p
= pgen("p", MP_NEW
, MP_NEW
, event
, ectx
, 4096, dsa_step
, &s
,
194 rabin_iters(pl
), pgen_test
, &r
)) == 0)
198 /* --- Find @g@ --- *
200 * The division returns remainder 1. This doesn't matter.
203 mpmont_create(&p
.mm
, dp
->p
);
204 qc
= MP_NEW
; mp_div(&qc
, 0, dp
->p
, dp
->q
);
208 if ((dp
->g
= pgen("g", MP_NEW
, MP_NEW
, event
, ectx
, 0, prim_step
, &i
,
209 1, prim_test
, &p
)) == 0)
215 mpmont_destroy(&p
.mm
);
216 s
.r
->ops
->destroy(s
.r
);
219 /* --- Tidy up when things go wrong --- */
223 mpmont_destroy(&p
.mm
);
228 s
.r
->ops
->destroy(s
.r
);
232 /*----- Test rig ----------------------------------------------------------*/
236 static int verify(dstr
*v
)
238 mp
*q
= *(mp
**)v
[2].buf
;
239 mp
*p
= *(mp
**)v
[3].buf
;
240 mp
*g
= *(mp
**)v
[4].buf
;
242 unsigned l
= *(unsigned *)v
[1].buf
;
246 rc
= dsa_gen(&dp
, 160, l
, 1, v
[0].buf
, v
[0].len
, pgen_evspin
, 0);
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);
253 fputs("\n p = ", stderr
); mp_writefile(p
, stderr
, 16);
254 fputs("\n g = ", stderr
); mp_writefile(g
, stderr
, 16);
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);
264 mp_drop(q
); mp_drop(p
); mp_drop(g
);
266 mp_drop(dp
.q
); mp_drop(dp
.p
); mp_drop(dp
.g
);
268 assert(mparena_count(MPARENA_GLOBAL
) == 1); /* Primorial! */
272 static test_chunk tests
[] = {
274 { &type_hex
, &type_int
, &type_mp
, &type_mp
, &type_mp
, 0 } },
278 int main(int argc
, char *argv
[])
281 test_run(argc
, argv
, tests
, SRCDIR
"/tests/dsa");
287 /*----- That's all, folks -------------------------------------------------*/