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

   1 /* -*-c-*-
   2  *
   3  * Generate DSA shared parameters
   4  *
   5  * (c) 1999 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Catacomb.
  11  *
  12  * Catacomb is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * Catacomb is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with Catacomb; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 /*----- Header files ------------------------------------------------------*/
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32
  33 #include "dsa.h"
  34 #include "dsarand.h"
  35 #include "fibrand.h"
  36 #include "mp.h"
  37 #include "mprand.h"
  38 #include "pgen.h"
  39 #include "prim.h"
  40 #include "sha.h"
  41
  42 /*----- The DSA stepper ---------------------------------------------------*/
  43
  44 /* --- @next@ --- *
  45  *
  46  * Arguments:   @pgen_event *ev@ = pointer to event block
  47  *              @dsa_stepctx *d@ = pointer to stepping context
  48  *
  49  * Returns:     A @PGEN@ result code.
  50  *
  51  * Use:         Steps the generator once, reads the result, and tests it.
  52  */
  53
  54 static int next(pgen_event *ev, dsa_stepctx *d)
  55 {
  56   mp *m;
  57   int rc;
  58
  59   /* --- Load the new candidate --- */
  60
  61   if (d->seedbuf)
  62     d->r->ops->misc(d->r, DSARAND_GETSEED, d->seedbuf);
  63   m = mprand(ev->m, d->bits, d->r, 0);
  64
  65   /* --- Force to be a multiple of @q@ --- */
  66
  67   if (d->q) {
  68     mp *r = MP_NEW;
  69     mp_div(0, &r, m, d->q);
  70     m = mp_sub(m, m, r);
  71     mp_drop(r);
  72   }
  73   m->v[0] |= d->or;
  74   ev->m = m;
  75
  76   /* --- Do the trial division --- */
  77
  78   rc = pfilt_smallfactor(m);
  79   d->count++;
  80
  81   /* --- Return the result --- */
  82
  83   return (rc);
  84 }
  85
  86 /* --- @dsa_step@ --- */
  87
  88 int dsa_step(int rq, pgen_event *ev, void *p)
  89 {
  90   dsa_stepctx *d = p;
  91
  92   switch (rq) {
  93     case PGEN_BEGIN:
  94     case PGEN_TRY:
  95       return (next(ev, d));
  96     case PGEN_DONE:
  97       return (PGEN_DONE);
  98   }
  99   return (PGEN_ABORT);
 100 }
 101
 102 /*----- Glue code ---------------------------------------------------------*/
 103
 104 /* --- @dsa_gen@ --- *
 105  *
 106  * Arguments:   @dsa_param *dp@ = where to store parameters
 107  *              @unsigned ql@ = length of @q@ in bits
 108  *              @unsigned pl@ = length of @p@ in bits
 109  *              @unsigned steps@ = number of steps to find @q@
 110  *              @const void *k@ = pointer to key material
 111  *              @size_t sz@ = size of key material
 112  *              @dsa_seed *ds@ = optional pointer for output seed information
 113  *              @pgen_proc *event@ = event handler function
 114  *              @void *ectx@ = argument for event handler
 115  *
 116  * Returns:     @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise.
 117  *
 118  * Use:         Generates the DSA shared parameters from a given seed value.
 119  *
 120  *              The parameters are a prime %$q$%, relatively small, and a
 121  *              large prime %$p = kq + 1$% for some %$k$%, together with a
 122  *              generator %$g$% of the cyclic subgroup of order %$q$%.  These
 123  *              are actually the same as the Diffie-Hellman parameter set,
 124  *              but the generation algorithm is different.
 125  *
 126  *              The algorithm used is a compatible extension of the method
 127  *              described in the DSA standard, FIPS 186.  The standard
 128  *              requires that %$q$% be 160 bits in size (i.e., @ql == 160@)
 129  *              and that the length of %$p$% be %$L = 512 + 64l$% for some
 130  *              %$l$%.  Neither limitation applies to this implementation.
 131  */
 132
 133 int dsa_gen(dsa_param *dp, unsigned ql, unsigned pl, unsigned steps,
 134             const void *k, size_t sz, dsa_seed *ds,
 135             pgen_proc *event, void *ectx)
 136 {
 137   dsa_stepctx s;
 138   prim_ctx p;
 139   int i;
 140   rabin r;
 141   mp *qc;
 142
 143   /* --- Initialize the stepping context --- */
 144
 145   s.r = dsarand_create(k, sz);
 146
 147   /* --- Find @q@ --- */
 148
 149   s.q = 0;
 150   s.r->ops->misc(s.r, DSARAND_PASSES, 2);
 151   s.bits = ql;
 152   s.count = 0;
 153   s.or = 1;
 154   if (!ds)
 155     s.seedbuf = 0;
 156   else {
 157     ds->sz = sz;
 158     ds->p = s.seedbuf = xmalloc(sz);
 159   }
 160   if ((dp->q = pgen("q", MP_NEW, MP_NEW, event, ectx, steps, dsa_step, &s,
 161                     rabin_iters(ql), pgen_test, &r)) == 0)
 162     goto fail_q;
 163
 164   /* --- Find @p@ --- */
 165
 166   s.count = ~0;
 167   s.q = mp_lsl(MP_NEW, dp->q, 1);
 168   s.r->ops->misc(s.r, DSARAND_PASSES, 1);
 169   s.bits = pl;
 170   s.seedbuf = 0;
 171   if ((dp->p = pgen("p", MP_NEW, MP_NEW, event, ectx, 4096, dsa_step, &s,
 172                     rabin_iters(pl), pgen_test, &r)) == 0)
 173     goto fail_p;
 174   mp_drop(s.q);
 175   if (ds)
 176     ds->count = s.count;
 177
 178   /* --- Find @g@ --- *
 179    *
 180    * The division returns remainder 1.  This doesn't matter.
 181    */
 182
 183   mpmont_create(&p.mm, dp->p);
 184   qc = MP_NEW; mp_div(&qc, 0, dp->p, dp->q);
 185   i = 0;
 186   p.exp = qc;
 187   p.n = 0;
 188   if ((dp->g = pgen("g", MP_NEW, MP_NEW, event, ectx, 0, prim_step, &i,
 189                     1, prim_test, &p)) == 0)
 190     goto fail_g;
 191
 192   /* --- Done --- */
 193
 194   mp_drop(qc);
 195   mpmont_destroy(&p.mm);
 196   s.r->ops->destroy(s.r);
 197   return (PGEN_DONE);
 198
 199   /* --- Tidy up when things go wrong --- */
 200
 201 fail_g:
 202   mp_drop(qc);
 203   mpmont_destroy(&p.mm);
 204 fail_p:
 205   mp_drop(dp->q);
 206   mp_drop(s.q);
 207 fail_q:
 208   s.r->ops->destroy(s.r);
 209   if (ds)
 210     xfree(ds->p);
 211   return (PGEN_ABORT);
 212 }
 213
 214 /*----- Test rig ----------------------------------------------------------*/
 215
 216 #ifdef TEST_RIG
 217
 218 static int verify(dstr *v)
 219 {
 220   mp *q = *(mp **)v[4].buf;
 221   mp *p = *(mp **)v[5].buf;
 222   mp *g = *(mp **)v[6].buf;
 223   dsa_param dp;
 224   dsa_seed ds;
 225   unsigned long l = *(unsigned long *)v[1].buf;
 226   unsigned long n = *(unsigned long *)v[3].buf;
 227   int ok = 1;
 228   int rc;
 229   keycheck kc;
 230   keycheck_reportctx kcr;
 231
 232   rc = dsa_gen(&dp, 160, l, 16, v[0].buf, v[0].len, &ds, pgen_evspin, 0);
 233   if (rc || ds.count != n || ds.sz != v[2].len ||
 234       memcmp(ds.p, v[2].buf, v[2].len) != 0 ||
 235       !MP_EQ(q, dp.q) || !MP_EQ(p, dp.p) || !MP_EQ(g, dp.g)) {
 236     fputs("\n*** gen failed", stderr);
 237     fputs("\nseed_in = ", stderr); type_hex.dump(&v[0], stderr);
 238     fprintf(stderr, "\nl = %lu", l);
 239     fputs("\nseed_out = ", stderr); type_hex.dump(&v[2], stderr);
 240     fprintf(stderr, "\ncount = %lu", n);
 241     fputs("\n   q = ", stderr); mp_writefile(q, stderr, 16);
 242     fputs("\n   p = ", stderr); mp_writefile(p, stderr, 16);
 243     fputs("\n   g = ", stderr); mp_writefile(g, stderr, 16);
 244     if (!rc) {
 245       dstr d;
 246       d.buf = ds.p; d.len = ds.sz;
 247       fputs("\nds.seed = ", stderr); type_hex.dump(&d, stderr);
 248       fprintf(stderr, "\nds.count = %u", ds.count);
 249       fputs("\ndp.q = ", stderr); mp_writefile(dp.q, stderr, 16);
 250       fputs("\ndp.p = ", stderr); mp_writefile(dp.p, stderr, 16);
 251       fputs("\ndp.g = ", stderr); mp_writefile(dp.g, stderr, 16);
 252     }
 253     fputc('\n', stderr);
 254     ok = 0;
 255   }
 256
 257   kcr.fp = stderr;
 258   kcr.sev = KCSEV_ERR;
 259   keycheck_init(&kc, keycheck_stdreport, &kcr);
 260   if (!rc)
 261     dsa_checkparam(&kc, &dp, &ds);
 262   if (!keycheck_allclear(&kc, KCSEV_ERR)) {
 263     fputs("\n*** gen failed check", stderr);
 264     fputs("\nseed_in = ", stderr); type_hex.dump(&v[0], stderr);
 265     fprintf(stderr, "\nl = %lu", l);
 266     fputs("\nseed_out = ", stderr); type_hex.dump(&v[2], stderr);
 267     fprintf(stderr, "\ncount = %lu", n);
 268     fputs("\n   q = ", stderr); mp_writefile(q, stderr, 16);
 269     fputs("\n   p = ", stderr); mp_writefile(p, stderr, 16);
 270     fputs("\n   g = ", stderr); mp_writefile(g, stderr, 16);
 271     fputc('\n', stderr);
 272     ok = 0;
 273   }
 274
 275   mp_drop(q); mp_drop(p); mp_drop(g);
 276   if (!rc) {
 277     mp_drop(dp.q); mp_drop(dp.p); mp_drop(dp.g); xfree(ds.p);
 278   }
 279   assert(mparena_count(MPARENA_GLOBAL) == 0);
 280   return (ok);
 281 }
 282
 283 static test_chunk tests[] = {
 284   { "gen", verify,
 285     { &type_hex, &type_ulong, &type_hex, &type_ulong,
 286       &type_mp, &type_mp, &type_mp, 0 }  },
 287   { 0, 0, { 0 } }
 288 };
 289
 290 int main(int argc, char *argv[])
 291 {
 292   sub_init();
 293   test_run(argc, argv, tests, SRCDIR "/t/dsa");
 294   return (0);
 295 }
 296
 297 #endif
 298
 299 /*----- That's all, folks -------------------------------------------------*/