| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: dsa-gen.c,v 1.6 2000/07/29 10:00:14 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 1.6 2000/07/29 10:00:14 mdw |
| 34 | * Rename `dsa_seed' to `dsa_gen' for consistency with other parameter- |
| 35 | * generation interfaces. |
| 36 | * |
| 37 | * Revision 1.5 2000/02/12 18:21:02 mdw |
| 38 | * Overhaul of key management (again). |
| 39 | * |
| 40 | * Revision 1.4 1999/12/22 15:52:44 mdw |
| 41 | * Reworking for new prime-search system. |
| 42 | * |
| 43 | * Revision 1.3 1999/12/10 23:18:38 mdw |
| 44 | * Change interface for suggested destinations. |
| 45 | * |
| 46 | * Revision 1.2 1999/11/20 22:23:48 mdw |
| 47 | * Allow event handler to abort the search process. |
| 48 | * |
| 49 | * Revision 1.1 1999/11/19 19:28:00 mdw |
| 50 | * Implementation of the Digital Signature Algorithm. |
| 51 | * |
| 52 | */ |
| 53 | |
| 54 | /*----- Header files ------------------------------------------------------*/ |
| 55 | |
| 56 | #include <stdio.h> |
| 57 | #include <stdlib.h> |
| 58 | |
| 59 | #include "dsa.h" |
| 60 | #include "dsarand.h" |
| 61 | #include "fibrand.h" |
| 62 | #include "mp.h" |
| 63 | #include "mprand.h" |
| 64 | #include "pgen.h" |
| 65 | #include "prim.h" |
| 66 | #include "primorial.h" |
| 67 | #include "sha.h" |
| 68 | |
| 69 | /*----- The DSA stepper ---------------------------------------------------*/ |
| 70 | |
| 71 | /* --- @next@ --- * |
| 72 | * |
| 73 | * Arguments: @pgen_event *ev@ = pointer to event block |
| 74 | * @dsa_stepctx *d@ = pointer to stepping context |
| 75 | * |
| 76 | * Returns: A @PGEN@ result code. |
| 77 | * |
| 78 | * Use: Steps the generator once, reads the result, and tests it. |
| 79 | */ |
| 80 | |
| 81 | static int next(pgen_event *ev, dsa_stepctx *d) |
| 82 | { |
| 83 | mp *m; |
| 84 | int rc; |
| 85 | |
| 86 | /* --- Load the new candidate --- */ |
| 87 | |
| 88 | m = mprand(ev->m, d->bits, d->r, d->or); |
| 89 | |
| 90 | /* --- Force to be a multiple of @q@ --- */ |
| 91 | |
| 92 | if (d->q) { |
| 93 | mp *r = MP_NEW; |
| 94 | mp_div(0, &r, m, d->q); |
| 95 | m = mp_sub(m, m, r); |
| 96 | mp_drop(r); |
| 97 | } |
| 98 | m->v[0] |= d->or; |
| 99 | ev->m = m; |
| 100 | |
| 101 | /* --- Do the trial division --- */ |
| 102 | |
| 103 | { |
| 104 | mp *g = MP_NEW; |
| 105 | mp_gcd(&g, 0, 0, m, primorial); |
| 106 | if (MP_CMP(g, ==, MP_ONE) || MP_CMP(g, ==, m)) |
| 107 | rc = PGEN_TRY; |
| 108 | else |
| 109 | rc = PGEN_FAIL; |
| 110 | mp_drop(g); |
| 111 | } |
| 112 | |
| 113 | /* --- Return the result --- */ |
| 114 | |
| 115 | return (rc); |
| 116 | } |
| 117 | |
| 118 | /* --- @dsa_step@ --- */ |
| 119 | |
| 120 | int dsa_step(int rq, pgen_event *ev, void *p) |
| 121 | { |
| 122 | dsa_stepctx *d = p; |
| 123 | |
| 124 | switch (rq) { |
| 125 | case PGEN_BEGIN: |
| 126 | primorial_setup(); |
| 127 | case PGEN_TRY: |
| 128 | return (next(ev, d)); |
| 129 | case PGEN_DONE: |
| 130 | return (PGEN_DONE); |
| 131 | } |
| 132 | return (PGEN_ABORT); |
| 133 | } |
| 134 | |
| 135 | /*----- Glue code ---------------------------------------------------------*/ |
| 136 | |
| 137 | /* --- @dsa_gen@ --- * |
| 138 | * |
| 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 |
| 147 | * |
| 148 | * Returns: @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise. |
| 149 | * |
| 150 | * Use: Generates the DSA shared parameters from a given seed value. |
| 151 | * |
| 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. |
| 157 | * |
| 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. |
| 163 | */ |
| 164 | |
| 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) |
| 167 | { |
| 168 | dsa_stepctx s; |
| 169 | prim_ctx p; |
| 170 | int i; |
| 171 | rabin r; |
| 172 | mp *qc; |
| 173 | |
| 174 | /* --- Initialize the stepping context --- */ |
| 175 | |
| 176 | s.r = dsarand_create(k, sz); |
| 177 | s.or = 1; |
| 178 | |
| 179 | /* --- Find @q@ --- */ |
| 180 | |
| 181 | s.q = 0; |
| 182 | s.r->ops->misc(s.r, DSARAND_PASSES, 2); |
| 183 | s.bits = ql; |
| 184 | if ((dp->q = pgen("q", MP_NEW, MP_NEW, event, ectx, steps, dsa_step, &s, |
| 185 | rabin_iters(ql), pgen_test, &r)) == 0) |
| 186 | goto fail_q; |
| 187 | |
| 188 | /* --- Find @p@ --- */ |
| 189 | |
| 190 | s.q = mp_lsl(MP_NEW, dp->q, 1); |
| 191 | s.r->ops->misc(s.r, DSARAND_PASSES, 1); |
| 192 | s.bits = pl; |
| 193 | if ((dp->p = pgen("p", MP_NEW, MP_NEW, event, ectx, 4096, dsa_step, &s, |
| 194 | rabin_iters(pl), pgen_test, &r)) == 0) |
| 195 | goto fail_p; |
| 196 | mp_drop(s.q); |
| 197 | |
| 198 | /* --- Find @g@ --- * |
| 199 | * |
| 200 | * The division returns remainder 1. This doesn't matter. |
| 201 | */ |
| 202 | |
| 203 | mpmont_create(&p.mm, dp->p); |
| 204 | qc = MP_NEW; mp_div(&qc, 0, dp->p, dp->q); |
| 205 | i = 0; |
| 206 | p.exp = qc; |
| 207 | p.n = 0; |
| 208 | if ((dp->g = pgen("g", MP_NEW, MP_NEW, event, ectx, 0, prim_step, &i, |
| 209 | 1, prim_test, &p)) == 0) |
| 210 | goto fail_g; |
| 211 | |
| 212 | /* --- Done --- */ |
| 213 | |
| 214 | mp_drop(qc); |
| 215 | mpmont_destroy(&p.mm); |
| 216 | s.r->ops->destroy(s.r); |
| 217 | return (PGEN_DONE); |
| 218 | |
| 219 | /* --- Tidy up when things go wrong --- */ |
| 220 | |
| 221 | fail_g: |
| 222 | mp_drop(qc); |
| 223 | mpmont_destroy(&p.mm); |
| 224 | fail_p: |
| 225 | mp_drop(dp->q); |
| 226 | mp_drop(s.q); |
| 227 | fail_q: |
| 228 | s.r->ops->destroy(s.r); |
| 229 | return (PGEN_ABORT); |
| 230 | } |
| 231 | |
| 232 | /*----- Test rig ----------------------------------------------------------*/ |
| 233 | |
| 234 | #ifdef TEST_RIG |
| 235 | |
| 236 | static int verify(dstr *v) |
| 237 | { |
| 238 | mp *q = *(mp **)v[2].buf; |
| 239 | mp *p = *(mp **)v[3].buf; |
| 240 | mp *g = *(mp **)v[4].buf; |
| 241 | dsa_param dp; |
| 242 | unsigned l = *(unsigned *)v[1].buf; |
| 243 | int ok = 1; |
| 244 | int rc; |
| 245 | |
| 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); |
| 255 | if (!rc) { |
| 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); |
| 259 | } |
| 260 | fputc('\n', stderr); |
| 261 | ok = 0; |
| 262 | } |
| 263 | |
| 264 | mp_drop(q); mp_drop(p); mp_drop(g); |
| 265 | if (!rc) { |
| 266 | mp_drop(dp.q); mp_drop(dp.p); mp_drop(dp.g); |
| 267 | } |
| 268 | assert(mparena_count(MPARENA_GLOBAL) == 1); /* Primorial! */ |
| 269 | return (ok); |
| 270 | } |
| 271 | |
| 272 | static test_chunk tests[] = { |
| 273 | { "gen", verify, |
| 274 | { &type_hex, &type_int, &type_mp, &type_mp, &type_mp, 0 } }, |
| 275 | { 0, 0, { 0 } } |
| 276 | }; |
| 277 | |
| 278 | int main(int argc, char *argv[]) |
| 279 | { |
| 280 | sub_init(); |
| 281 | test_run(argc, argv, tests, SRCDIR "/tests/dsa"); |
| 282 | return (0); |
| 283 | } |
| 284 | |
| 285 | #endif |
| 286 | |
| 287 | /*----- That's all, folks -------------------------------------------------*/ |