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

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