lib/libcrypto/bn/bn_x931p.c

   1 /* $OpenBSD: bn_x931p.c,v 1.10 2017/01/25 06:15:44 beck Exp $ */
   2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
   3  * project 2005.
   4  */
   5 /* ====================================================================
   6  * Copyright (c) 2005 The OpenSSL Project.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  *
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in
  17  *    the documentation and/or other materials provided with the
  18  *    distribution.
  19  *
  20  * 3. All advertising materials mentioning features or use of this
  21  *    software must display the following acknowledgment:
  22  *    "This product includes software developed by the OpenSSL Project
  23  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  24  *
  25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  26  *    endorse or promote products derived from this software without
  27  *    prior written permission. For written permission, please contact
  28  *    licensing@OpenSSL.org.
  29  *
  30  * 5. Products derived from this software may not be called "OpenSSL"
  31  *    nor may "OpenSSL" appear in their names without prior written
  32  *    permission of the OpenSSL Project.
  33  *
  34  * 6. Redistributions of any form whatsoever must retain the following
  35  *    acknowledgment:
  36  *    "This product includes software developed by the OpenSSL Project
  37  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  38  *
  39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  50  * OF THE POSSIBILITY OF SUCH DAMAGE.
  51  * ====================================================================
  52  *
  53  * This product includes cryptographic software written by Eric Young
  54  * (eay@cryptsoft.com).  This product includes software written by Tim
  55  * Hudson (tjh@cryptsoft.com).
  56  *
  57  */
  58
  59 #include <stdio.h>
  60 #include <openssl/bn.h>
  61
  62 #include "bn_lcl.h"
  63
  64 /* X9.31 routines for prime derivation */
  65
  66 /* X9.31 prime derivation. This is used to generate the primes pi
  67  * (p1, p2, q1, q2) from a parameter Xpi by checking successive odd
  68  * integers.
  69  */
  70
  71 static int
  72 bn_x931_derive_pi(BIGNUM *pi, const BIGNUM *Xpi, BN_CTX *ctx, BN_GENCB *cb)
  73 {
  74         int i = 0;
  75
  76         if (!BN_copy(pi, Xpi))
  77                 return 0;
  78         if (!BN_is_odd(pi) && !BN_add_word(pi, 1))
  79                 return 0;
  80         for (;;) {
  81                 i++;
  82                 BN_GENCB_call(cb, 0, i);
  83                 /* NB 27 MR is specificed in X9.31 */
  84                 if (BN_is_prime_fasttest_ex(pi, 27, ctx, 1, cb))
  85                         break;
  86                 if (!BN_add_word(pi, 2))
  87                         return 0;
  88         }
  89         BN_GENCB_call(cb, 2, i);
  90         return 1;
  91 }
  92
  93 /* This is the main X9.31 prime derivation function. From parameters
  94  * Xp1, Xp2 and Xp derive the prime p. If the parameters p1 or p2 are
  95  * not NULL they will be returned too: this is needed for testing.
  96  */
  97
  98 int
  99 BN_X931_derive_prime_ex(BIGNUM *p, BIGNUM *p1, BIGNUM *p2, const BIGNUM *Xp,
 100     const BIGNUM *Xp1, const BIGNUM *Xp2, const BIGNUM *e, BN_CTX *ctx,
 101     BN_GENCB *cb)
 102 {
 103         int ret = 0;
 104
 105         BIGNUM *t, *p1p2, *pm1;
 106
 107         /* Only even e supported */
 108         if (!BN_is_odd(e))
 109                 return 0;
 110
 111         BN_CTX_start(ctx);
 112         if (p1 == NULL) {
 113                 if ((p1 = BN_CTX_get(ctx)) == NULL)
 114                         goto err;
 115         }
 116         if (p2 == NULL) {
 117                 if ((p2 = BN_CTX_get(ctx)) == NULL)
 118                         goto err;
 119         }
 120
 121         if ((t = BN_CTX_get(ctx)) == NULL)
 122                 goto err;
 123         if ((p1p2 = BN_CTX_get(ctx)) == NULL)
 124                 goto err;
 125         if ((pm1 = BN_CTX_get(ctx)) == NULL)
 126                 goto err;
 127
 128         if (!bn_x931_derive_pi(p1, Xp1, ctx, cb))
 129                 goto err;
 130
 131         if (!bn_x931_derive_pi(p2, Xp2, ctx, cb))
 132                 goto err;
 133
 134         if (!BN_mul(p1p2, p1, p2, ctx))
 135                 goto err;
 136
 137         /* First set p to value of Rp */
 138
 139         if (!BN_mod_inverse_ct(p, p2, p1, ctx))
 140                 goto err;
 141
 142         if (!BN_mul(p, p, p2, ctx))
 143                 goto err;
 144
 145         if (!BN_mod_inverse_ct(t, p1, p2, ctx))
 146                 goto err;
 147
 148         if (!BN_mul(t, t, p1, ctx))
 149                 goto err;
 150
 151         if (!BN_sub(p, p, t))
 152                 goto err;
 153
 154         if (p->neg && !BN_add(p, p, p1p2))
 155                 goto err;
 156
 157         /* p now equals Rp */
 158
 159         if (!BN_mod_sub(p, p, Xp, p1p2, ctx))
 160                 goto err;
 161
 162         if (!BN_add(p, p, Xp))
 163                 goto err;
 164
 165         /* p now equals Yp0 */
 166
 167         for (;;) {
 168                 int i = 1;
 169                 BN_GENCB_call(cb, 0, i++);
 170                 if (!BN_copy(pm1, p))
 171                         goto err;
 172                 if (!BN_sub_word(pm1, 1))
 173                         goto err;
 174                 if (!BN_gcd_ct(t, pm1, e, ctx))
 175                         goto err;
 176                 if (BN_is_one(t)
 177                 /* X9.31 specifies 8 MR and 1 Lucas test or any prime test
 178                  * offering similar or better guarantees 50 MR is considerably
 179                  * better.
 180                  */
 181                     && BN_is_prime_fasttest_ex(p, 50, ctx, 1, cb))
 182                         break;
 183                 if (!BN_add(p, p, p1p2))
 184                         goto err;
 185         }
 186
 187         BN_GENCB_call(cb, 3, 0);
 188
 189         ret = 1;
 190
 191 err:
 192
 193         BN_CTX_end(ctx);
 194
 195         return ret;
 196 }
 197
 198 /* Generate pair of paramters Xp, Xq for X9.31 prime generation.
 199  * Note: nbits paramter is sum of number of bits in both.
 200  */
 201
 202 int
 203 BN_X931_generate_Xpq(BIGNUM *Xp, BIGNUM *Xq, int nbits, BN_CTX *ctx)
 204 {
 205         BIGNUM *t;
 206         int i;
 207         int ret = 0;
 208
 209         /* Number of bits for each prime is of the form
 210          * 512+128s for s = 0, 1, ...
 211          */
 212         if ((nbits < 1024) || (nbits & 0xff))
 213                 return 0;
 214         nbits >>= 1;
 215         /* The random value Xp must be between sqrt(2) * 2^(nbits-1) and
 216          * 2^nbits - 1. By setting the top two bits we ensure that the lower
 217          * bound is exceeded.
 218          */
 219         if (!BN_rand(Xp, nbits, 1, 0))
 220                 return 0;
 221
 222         BN_CTX_start(ctx);
 223         if ((t = BN_CTX_get(ctx)) == NULL)
 224                 goto err;
 225
 226         for (i = 0; i < 1000; i++) {
 227                 if (!BN_rand(Xq, nbits, 1, 0))
 228                         goto err;
 229                 /* Check that |Xp - Xq| > 2^(nbits - 100) */
 230                 BN_sub(t, Xp, Xq);
 231                 if (BN_num_bits(t) > (nbits - 100))
 232                         break;
 233         }
 234
 235         if (i < 1000)
 236                 ret = 1;
 237
 238 err:
 239         BN_CTX_end(ctx);
 240
 241         return ret;
 242 }
 243
 244 /* Generate primes using X9.31 algorithm. Of the values p, p1, p2, Xp1
 245  * and Xp2 only 'p' needs to be non-NULL. If any of the others are not NULL
 246  * the relevant parameter will be stored in it.
 247  *
 248  * Due to the fact that |Xp - Xq| > 2^(nbits - 100) must be satisfied Xp and Xq
 249  * are generated using the previous function and supplied as input.
 250  */
 251
 252 int
 253 BN_X931_generate_prime_ex(BIGNUM *p, BIGNUM *p1, BIGNUM *p2, BIGNUM *Xp1,
 254     BIGNUM *Xp2, const BIGNUM *Xp, const BIGNUM *e, BN_CTX *ctx, BN_GENCB *cb)
 255 {
 256         int ret = 0;
 257
 258         BN_CTX_start(ctx);
 259         if (Xp1 == NULL) {
 260                 if ((Xp1 = BN_CTX_get(ctx)) == NULL)
 261                         goto error;
 262         }
 263         if (Xp2 == NULL) {
 264                 if ((Xp2 = BN_CTX_get(ctx)) == NULL)
 265                         goto error;
 266         }
 267
 268         if (!BN_rand(Xp1, 101, 0, 0))
 269                 goto error;
 270         if (!BN_rand(Xp2, 101, 0, 0))
 271                 goto error;
 272         if (!BN_X931_derive_prime_ex(p, p1, p2, Xp, Xp1, Xp2, e, ctx, cb))
 273                 goto error;
 274
 275         ret = 1;
 276
 277 error:
 278         BN_CTX_end(ctx);
 279
 280         return ret;
 281 }