git.distorted.org.uk Git - u/mdw/catacomb/blob - dsa-gen.c

   1 /* -*-c-*-
   2  *
   3  * $Id: dsa-gen.c,v 1.8 2000/10/08 12:12:47 mdw Exp $
   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 $
  33  * Revision 1.8  2000/10/08 12:12:47  mdw
  34  * Use @MP_EQ@ instead of @MP_CMP@.  Remove vestages of @primorial@.
  35  *
  36  * Revision 1.7  2000/08/15 21:45:05  mdw
  37  * Use the new trial division equipment in pfilt.  This gives a 10%
  38  * performance improvement in dsa-gen.t.
  39  *
  40  * Revision 1.6  2000/07/29 10:00:14  mdw
  41  * Rename `dsa_seed' to `dsa_gen' for consistency with other parameter-
  42  * generation interfaces.
  43  *
  44  * Revision 1.5  2000/02/12 18:21:02  mdw
  45  * Overhaul of key management (again).
  46  *
  47  * Revision 1.4  1999/12/22 15:52:44  mdw
  48  * Reworking for new prime-search system.
  49  *
  50  * Revision 1.3  1999/12/10 23:18:38  mdw
  51  * Change interface for suggested destinations.
  52  *
  53  * Revision 1.2  1999/11/20 22:23:48  mdw
  54  * Allow event handler to abort the search process.
  55  *
  56  * Revision 1.1  1999/11/19 19:28:00  mdw
  57  * Implementation of the Digital Signature Algorithm.
  58  *
  59  */
  60
  61 /*----- Header files ------------------------------------------------------*/
  62
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65
  66 #include "dsa.h"
  67 #include "dsarand.h"
  68 #include "fibrand.h"
  69 #include "mp.h"
  70 #include "mprand.h"
  71 #include "pgen.h"
  72 #include "prim.h"
  73 #include "sha.h"
  74
  75 /*----- The DSA stepper ---------------------------------------------------*/
  76
  77 /* --- @next@ --- *
  78  *
  79  * Arguments:   @pgen_event *ev@ = pointer to event block
  80  *              @dsa_stepctx *d@ = pointer to stepping context
  81  *
  82  * Returns:     A @PGEN@ result code.
  83  *
  84  * Use:         Steps the generator once, reads the result, and tests it.
  85  */
  86
  87 static int next(pgen_event *ev, dsa_stepctx *d)
  88 {
  89   mp *m;
  90   int rc;
  91
  92   /* --- Load the new candidate --- */
  93
  94   m = mprand(ev->m, d->bits, d->r, d->or);
  95
  96   /* --- Force to be a multiple of @q@ --- */
  97
  98   if (d->q) {
  99     mp *r = MP_NEW;
 100     mp_div(0, &r, m, d->q);
 101     m = mp_sub(m, m, r);
 102     mp_drop(r);
 103   }
 104   m->v[0] |= d->or;
 105   ev->m = m;
 106
 107   /* --- Do the trial division --- */
 108
 109   rc = pfilt_smallfactor(m);
 110
 111   /* --- Return the result --- */
 112
 113   return (rc);
 114 }
 115
 116 /* --- @dsa_step@ --- */
 117
 118 int dsa_step(int rq, pgen_event *ev, void *p)
 119 {
 120   dsa_stepctx *d = p;
 121
 122   switch (rq) {
 123     case PGEN_BEGIN:
 124     case PGEN_TRY:
 125       return (next(ev, d));
 126     case PGEN_DONE:
 127       return (PGEN_DONE);
 128   }
 129   return (PGEN_ABORT);
 130 }
 131
 132 /*----- Glue code ---------------------------------------------------------*/
 133
 134 /* --- @dsa_gen@ --- *
 135  *
 136  * Arguments:   @dsa_param *dp@ = where to store parameters
 137  *              @unsigned ql@ = length of @q@ in bits
 138  *              @unsigned pl@ = length of @p@ in bits
 139  *              @unsigned steps@ = number of steps to find @q@
 140  *              @const void *k@ = pointer to key material
 141  *              @size_t sz@ = size of key material
 142  *              @pgen_proc *event@ = event handler function
 143  *              @void *ectx@ = argument for event handler
 144  *
 145  * Returns:     @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise.
 146  *
 147  * Use:         Generates the DSA shared parameters from a given seed value.
 148  *
 149  *              The parameters are a prime %$q$%, relatively small, and a
 150  *              large prime %$p = kq + 1$% for some %$k$%, together with a
 151  *              generator %$g$% of the cyclic subgroup of order %$q$%.  These
 152  *              are actually the same as the Diffie-Hellman parameter set,
 153  *              but the generation algorithm is different.
 154  *
 155  *              The algorithm used is a compatible extension of the method
 156  *              described in the DSA standard, FIPS 186.  The standard
 157  *              requires that %$q$% be 160 bits in size (i.e., @ql == 160@)
 158  *              and that the length of %$p$% be %$L = 512 + 64l$% for some
 159  *              %$l$%.  Neither limitation applies to this implementation.
 160  */
 161
 162 int dsa_gen(dsa_param *dp, unsigned ql, unsigned pl, unsigned steps,
 163             const void *k, size_t sz, pgen_proc *event, void *ectx)
 164 {
 165   dsa_stepctx s;
 166   prim_ctx p;
 167   int i;
 168   rabin r;
 169   mp *qc;
 170
 171   /* --- Initialize the stepping context --- */
 172
 173   s.r = dsarand_create(k, sz);
 174   s.or = 1;
 175
 176   /* --- Find @q@ --- */
 177
 178   s.q = 0;
 179   s.r->ops->misc(s.r, DSARAND_PASSES, 2);
 180   s.bits = ql;
 181   if ((dp->q = pgen("q", MP_NEW, MP_NEW, event, ectx, steps, dsa_step, &s,
 182                     rabin_iters(ql), pgen_test, &r)) == 0)
 183     goto fail_q;
 184
 185   /* --- Find @p@ --- */
 186
 187   s.q = mp_lsl(MP_NEW, dp->q, 1);
 188   s.r->ops->misc(s.r, DSARAND_PASSES, 1);
 189   s.bits = pl;
 190   if ((dp->p = pgen("p", MP_NEW, MP_NEW, event, ectx, 4096, dsa_step, &s,
 191                     rabin_iters(pl), pgen_test, &r)) == 0)
 192     goto fail_p;
 193   mp_drop(s.q);
 194
 195   /* --- Find @g@ --- *
 196    *
 197    * The division returns remainder 1.  This doesn't matter.
 198    */
 199
 200   mpmont_create(&p.mm, dp->p);
 201   qc = MP_NEW; mp_div(&qc, 0, dp->p, dp->q);
 202   i = 0;
 203   p.exp = qc;
 204   p.n = 0;
 205   if ((dp->g = pgen("g", MP_NEW, MP_NEW, event, ectx, 0, prim_step, &i,
 206                     1, prim_test, &p)) == 0)
 207     goto fail_g;
 208
 209   /* --- Done --- */
 210
 211   mp_drop(qc);
 212   mpmont_destroy(&p.mm);
 213   s.r->ops->destroy(s.r);
 214   return (PGEN_DONE);
 215
 216   /* --- Tidy up when things go wrong --- */
 217
 218 fail_g:
 219   mp_drop(qc);
 220   mpmont_destroy(&p.mm);
 221 fail_p:
 222   mp_drop(dp->q);
 223   mp_drop(s.q);
 224 fail_q:
 225   s.r->ops->destroy(s.r);
 226   return (PGEN_ABORT);
 227 }
 228
 229 /*----- Test rig ----------------------------------------------------------*/
 230
 231 #ifdef TEST_RIG
 232
 233 static int verify(dstr *v)
 234 {
 235   mp *q = *(mp **)v[2].buf;
 236   mp *p = *(mp **)v[3].buf;
 237   mp *g = *(mp **)v[4].buf;
 238   dsa_param dp;
 239   unsigned l = *(unsigned *)v[1].buf;
 240   int ok = 1;
 241   int rc;
 242
 243   rc = dsa_gen(&dp, 160, l, 1, v[0].buf, v[0].len, pgen_evspin, 0);
 244   if (rc || !MP_EQ(q, dp.q) ||
 245       !MP_EQ(p, dp.p) || !MP_EQ(g, dp.g)) {
 246     fputs("\n*** gen failed", stderr);
 247     fputs("\nseed = ", stderr); type_hex.dump(&v[0], stderr);
 248     fprintf(stderr, "\nl = %u", l);
 249     fputs("\n   q = ", stderr); mp_writefile(q, stderr, 16);
 250     fputs("\n   p = ", stderr); mp_writefile(p, stderr, 16);
 251     fputs("\n   g = ", stderr); mp_writefile(g, stderr, 16);
 252     if (!rc) {
 253       fputs("\ndp.q = ", stderr); mp_writefile(dp.q, stderr, 16);
 254       fputs("\ndp.p = ", stderr); mp_writefile(dp.p, stderr, 16);
 255       fputs("\ndp.g = ", stderr); mp_writefile(dp.g, stderr, 16);
 256     }
 257     fputc('\n', stderr);
 258     ok = 0;
 259   }
 260
 261   mp_drop(q); mp_drop(p); mp_drop(g);
 262   if (!rc) {
 263     mp_drop(dp.q); mp_drop(dp.p); mp_drop(dp.g);
 264   }
 265   assert(mparena_count(MPARENA_GLOBAL) == 0);
 266   return (ok);
 267 }
 268
 269 static test_chunk tests[] = {
 270   { "gen", verify,
 271     { &type_hex, &type_int, &type_mp, &type_mp, &type_mp, 0 }  },
 272   { 0, 0, { 0 } }
 273 };
 274
 275 int main(int argc, char *argv[])
 276 {
 277   sub_init();
 278   test_run(argc, argv, tests, SRCDIR "/tests/dsa");
 279   return (0);
 280 }
 281
 282 #endif
 283
 284 /*----- That's all, folks -------------------------------------------------*/