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

   1 /* -*-c-*-
   2  *
   3  * $Id: dsa-gen.c,v 1.9 2001/02/03 16:09:29 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 1.9  2001/02/03 16:09:29  mdw
  34  * Allow the caller to fetch the parameter generation seed and counter.
  35  *
  36  * Revision 1.8  2000/10/08 12:12:47  mdw
  37  * Use @MP_EQ@ instead of @MP_CMP@.  Remove vestages of @primorial@.
  38  *
  39  * Revision 1.7  2000/08/15 21:45:05  mdw
  40  * Use the new trial division equipment in pfilt.  This gives a 10%
  41  * performance improvement in dsa-gen.t.
  42  *
  43  * Revision 1.6  2000/07/29 10:00:14  mdw
  44  * Rename `dsa_seed' to `dsa_gen' for consistency with other parameter-
  45  * generation interfaces.
  46  *
  47  * Revision 1.5  2000/02/12 18:21:02  mdw
  48  * Overhaul of key management (again).
  49  *
  50  * Revision 1.4  1999/12/22 15:52:44  mdw
  51  * Reworking for new prime-search system.
  52  *
  53  * Revision 1.3  1999/12/10 23:18:38  mdw
  54  * Change interface for suggested destinations.
  55  *
  56  * Revision 1.2  1999/11/20 22:23:48  mdw
  57  * Allow event handler to abort the search process.
  58  *
  59  * Revision 1.1  1999/11/19 19:28:00  mdw
  60  * Implementation of the Digital Signature Algorithm.
  61  *
  62  */
  63
  64 /*----- Header files ------------------------------------------------------*/
  65
  66 #include <stdio.h>
  67 #include <stdlib.h>
  68
  69 #include "dsa.h"
  70 #include "dsarand.h"
  71 #include "fibrand.h"
  72 #include "mp.h"
  73 #include "mprand.h"
  74 #include "pgen.h"
  75 #include "prim.h"
  76 #include "sha.h"
  77
  78 /*----- The DSA stepper ---------------------------------------------------*/
  79
  80 /* --- @next@ --- *
  81  *
  82  * Arguments:   @pgen_event *ev@ = pointer to event block
  83  *              @dsa_stepctx *d@ = pointer to stepping context
  84  *
  85  * Returns:     A @PGEN@ result code.
  86  *
  87  * Use:         Steps the generator once, reads the result, and tests it.
  88  */
  89
  90 static int next(pgen_event *ev, dsa_stepctx *d)
  91 {
  92   mp *m;
  93   int rc;
  94
  95   /* --- Load the new candidate --- */
  96
  97   if (d->seedbuf)
  98     d->r->ops->misc(d->r, DSARAND_GETSEED, d->seedbuf);
  99   m = mprand(ev->m, d->bits, d->r, 0);
 100
 101   /* --- Force to be a multiple of @q@ --- */
 102
 103   if (d->q) {
 104     mp *r = MP_NEW;
 105     mp_div(0, &r, m, d->q);
 106     m = mp_sub(m, m, r);
 107     mp_drop(r);
 108   }
 109   m->v[0] |= d->or;
 110   ev->m = m;
 111
 112   /* --- Do the trial division --- */
 113
 114   rc = pfilt_smallfactor(m);
 115   d->count++;
 116
 117   /* --- Return the result --- */
 118
 119   return (rc);
 120 }
 121
 122 /* --- @dsa_step@ --- */
 123
 124 int dsa_step(int rq, pgen_event *ev, void *p)
 125 {
 126   dsa_stepctx *d = p;
 127
 128   switch (rq) {
 129     case PGEN_BEGIN:
 130     case PGEN_TRY:
 131       return (next(ev, d));
 132     case PGEN_DONE:
 133       return (PGEN_DONE);
 134   }
 135   return (PGEN_ABORT);
 136 }
 137
 138 /*----- Glue code ---------------------------------------------------------*/
 139
 140 /* --- @dsa_gen@ --- *
 141  *
 142  * Arguments:   @dsa_param *dp@ = where to store parameters
 143  *              @unsigned ql@ = length of @q@ in bits
 144  *              @unsigned pl@ = length of @p@ in bits
 145  *              @unsigned steps@ = number of steps to find @q@
 146  *              @const void *k@ = pointer to key material
 147  *              @size_t sz@ = size of key material
 148  *              @dsa_seed *ds@ = optional pointer for output seed information
 149  *              @pgen_proc *event@ = event handler function
 150  *              @void *ectx@ = argument for event handler
 151  *
 152  * Returns:     @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise.
 153  *
 154  * Use:         Generates the DSA shared parameters from a given seed value.
 155  *
 156  *              The parameters are a prime %$q$%, relatively small, and a
 157  *              large prime %$p = kq + 1$% for some %$k$%, together with a
 158  *              generator %$g$% of the cyclic subgroup of order %$q$%.  These
 159  *              are actually the same as the Diffie-Hellman parameter set,
 160  *              but the generation algorithm is different.
 161  *
 162  *              The algorithm used is a compatible extension of the method
 163  *              described in the DSA standard, FIPS 186.  The standard
 164  *              requires that %$q$% be 160 bits in size (i.e., @ql == 160@)
 165  *              and that the length of %$p$% be %$L = 512 + 64l$% for some
 166  *              %$l$%.  Neither limitation applies to this implementation.
 167  */
 168
 169 int dsa_gen(dsa_param *dp, unsigned ql, unsigned pl, unsigned steps,
 170             const void *k, size_t sz, dsa_seed *ds,
 171             pgen_proc *event, void *ectx)
 172 {
 173   dsa_stepctx s;
 174   prim_ctx p;
 175   int i;
 176   rabin r;
 177   mp *qc;
 178
 179   /* --- Initialize the stepping context --- */
 180
 181   s.r = dsarand_create(k, sz);
 182
 183   /* --- Find @q@ --- */
 184
 185   s.q = 0;
 186   s.r->ops->misc(s.r, DSARAND_PASSES, 2);
 187   s.bits = ql;
 188   s.count = 0;
 189   s.or = 1;
 190   if (!ds)
 191     s.seedbuf = 0;
 192   else {
 193     ds->sz = sz;
 194     ds->p = s.seedbuf = xmalloc(sz);
 195   }
 196   if ((dp->q = pgen("q", MP_NEW, MP_NEW, event, ectx, steps, dsa_step, &s,
 197                     rabin_iters(ql), pgen_test, &r)) == 0)
 198     goto fail_q;
 199
 200   /* --- Find @p@ --- */
 201
 202   s.count = ~0;
 203   s.q = mp_lsl(MP_NEW, dp->q, 1);
 204   s.r->ops->misc(s.r, DSARAND_PASSES, 1);
 205   s.bits = pl;
 206   s.seedbuf = 0;
 207   if ((dp->p = pgen("p", MP_NEW, MP_NEW, event, ectx, 4096, dsa_step, &s,
 208                     rabin_iters(pl), pgen_test, &r)) == 0)
 209     goto fail_p;
 210   mp_drop(s.q);
 211   if (ds)
 212     ds->count = s.count;
 213
 214   /* --- Find @g@ --- *
 215    *
 216    * The division returns remainder 1.  This doesn't matter.
 217    */
 218
 219   mpmont_create(&p.mm, dp->p);
 220   qc = MP_NEW; mp_div(&qc, 0, dp->p, dp->q);
 221   i = 0;
 222   p.exp = qc;
 223   p.n = 0;
 224   if ((dp->g = pgen("g", MP_NEW, MP_NEW, event, ectx, 0, prim_step, &i,
 225                     1, prim_test, &p)) == 0)
 226     goto fail_g;
 227
 228   /* --- Done --- */
 229
 230   mp_drop(qc);
 231   mpmont_destroy(&p.mm);
 232   s.r->ops->destroy(s.r);
 233   return (PGEN_DONE);
 234
 235   /* --- Tidy up when things go wrong --- */
 236
 237 fail_g:
 238   mp_drop(qc);
 239   mpmont_destroy(&p.mm);
 240 fail_p:
 241   mp_drop(dp->q);
 242   mp_drop(s.q);
 243 fail_q:
 244   s.r->ops->destroy(s.r);
 245   if (ds)
 246     xfree(ds->p);
 247   return (PGEN_ABORT);
 248 }
 249
 250 /*----- Test rig ----------------------------------------------------------*/
 251
 252 #ifdef TEST_RIG
 253
 254 static int verify(dstr *v)
 255 {
 256   mp *q = *(mp **)v[4].buf;
 257   mp *p = *(mp **)v[5].buf;
 258   mp *g = *(mp **)v[6].buf;
 259   dsa_param dp;
 260   dsa_seed ds;
 261   unsigned long l = *(unsigned long *)v[1].buf;
 262   unsigned long n = *(unsigned long *)v[3].buf;
 263   int ok = 1;
 264   int rc;
 265   keycheck kc;
 266   keycheck_reportctx kcr;
 267
 268   rc = dsa_gen(&dp, 160, l, 16, v[0].buf, v[0].len, &ds, pgen_evspin, 0);
 269   if (rc || ds.count != n || ds.sz != v[2].len ||
 270       memcmp(ds.p, v[2].buf, v[2].len) != 0 ||
 271       !MP_EQ(q, dp.q) || !MP_EQ(p, dp.p) || !MP_EQ(g, dp.g)) {
 272     fputs("\n*** gen failed", stderr);
 273     fputs("\nseed_in = ", stderr); type_hex.dump(&v[0], stderr);
 274     fprintf(stderr, "\nl = %lu", l);
 275     fputs("\nseed_out = ", stderr); type_hex.dump(&v[2], stderr);
 276     fprintf(stderr, "\ncount = %lu", n);
 277     fputs("\n   q = ", stderr); mp_writefile(q, stderr, 16);
 278     fputs("\n   p = ", stderr); mp_writefile(p, stderr, 16);
 279     fputs("\n   g = ", stderr); mp_writefile(g, stderr, 16);
 280     if (!rc) {
 281       dstr d;
 282       d.buf = ds.p; d.len = ds.sz;
 283       fputs("\nds.seed = ", stderr); type_hex.dump(&d, stderr);
 284       fprintf(stderr, "\nds.count = %u", ds.count);
 285       fputs("\ndp.q = ", stderr); mp_writefile(dp.q, stderr, 16);
 286       fputs("\ndp.p = ", stderr); mp_writefile(dp.p, stderr, 16);
 287       fputs("\ndp.g = ", stderr); mp_writefile(dp.g, stderr, 16);
 288     }
 289     fputc('\n', stderr);
 290     ok = 0;
 291   }
 292
 293   kcr.fp = stderr;
 294   kcr.sev = KCSEV_ERR;
 295   keycheck_init(&kc, keycheck_stdreport, &kcr);
 296   if (!rc)
 297     dsa_checkparam(&kc, &dp, &ds);
 298   if (!keycheck_allclear(&kc, KCSEV_ERR)) {
 299     fputs("\n*** gen failed check", stderr);
 300     fputs("\nseed_in = ", stderr); type_hex.dump(&v[0], stderr);
 301     fprintf(stderr, "\nl = %lu", l);
 302     fputs("\nseed_out = ", stderr); type_hex.dump(&v[2], stderr);
 303     fprintf(stderr, "\ncount = %lu", n);
 304     fputs("\n   q = ", stderr); mp_writefile(q, stderr, 16);
 305     fputs("\n   p = ", stderr); mp_writefile(p, stderr, 16);
 306     fputs("\n   g = ", stderr); mp_writefile(g, stderr, 16);
 307     fputc('\n', stderr);
 308     ok = 0;
 309   }
 310
 311   mp_drop(q); mp_drop(p); mp_drop(g);
 312   if (!rc) {
 313     mp_drop(dp.q); mp_drop(dp.p); mp_drop(dp.g); xfree(ds.p);
 314   }
 315   assert(mparena_count(MPARENA_GLOBAL) == 0);
 316   return (ok);
 317 }
 318
 319 static test_chunk tests[] = {
 320   { "gen", verify,
 321     { &type_hex, &type_ulong, &type_hex, &type_ulong,
 322       &type_mp, &type_mp, &type_mp, 0 }  },
 323   { 0, 0, { 0 } }
 324 };
 325
 326 int main(int argc, char *argv[])
 327 {
 328   sub_init();
 329   test_run(argc, argv, tests, SRCDIR "/tests/dsa");
 330   return (0);
 331 }
 332
 333 #endif
 334
 335 /*----- That's all, folks -------------------------------------------------*/