crypto/openssl/crypto/bn/bn_exp2.c

   1 /* crypto/bn/bn_exp2.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58 /* ====================================================================
  59  * Copyright (c) 1998-2000 The OpenSSL Project.  All rights reserved.
  60  *
  61  * Redistribution and use in source and binary forms, with or without
  62  * modification, are permitted provided that the following conditions
  63  * are met:
  64  *
  65  * 1. Redistributions of source code must retain the above copyright
  66  *    notice, this list of conditions and the following disclaimer.
  67  *
  68  * 2. Redistributions in binary form must reproduce the above copyright
  69  *    notice, this list of conditions and the following disclaimer in
  70  *    the documentation and/or other materials provided with the
  71  *    distribution.
  72  *
  73  * 3. All advertising materials mentioning features or use of this
  74  *    software must display the following acknowledgment:
  75  *    "This product includes software developed by the OpenSSL Project
  76  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  77  *
  78  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  79  *    endorse or promote products derived from this software without
  80  *    prior written permission. For written permission, please contact
  81  *    openssl-core@openssl.org.
  82  *
  83  * 5. Products derived from this software may not be called "OpenSSL"
  84  *    nor may "OpenSSL" appear in their names without prior written
  85  *    permission of the OpenSSL Project.
  86  *
  87  * 6. Redistributions of any form whatsoever must retain the following
  88  *    acknowledgment:
  89  *    "This product includes software developed by the OpenSSL Project
  90  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  91  *
  92  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  93  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  94  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  95  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  96  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  97  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  98  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  99  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 100  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 101  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 102  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 103  * OF THE POSSIBILITY OF SUCH DAMAGE.
 104  * ====================================================================
 105  *
 106  * This product includes cryptographic software written by Eric Young
 107  * (eay@cryptsoft.com).  This product includes software written by Tim
 108  * Hudson (tjh@cryptsoft.com).
 109  *
 110  */
 111
 112 #include <stdio.h>
 113 #include "cryptlib.h"
 114 #include "bn_lcl.h"
 115
 116 #define TABLE_SIZE      32
 117
 118 int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
 119         const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
 120         BN_CTX *ctx, BN_MONT_CTX *in_mont)
 121         {
 122         int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;
 123         int r_is_one=1;
 124         BIGNUM *d,*r;
 125         const BIGNUM *a_mod_m;
 126         /* Tables of variables obtained from 'ctx' */
 127         BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
 128         BN_MONT_CTX *mont=NULL;
 129
 130         bn_check_top(a1);
 131         bn_check_top(p1);
 132         bn_check_top(a2);
 133         bn_check_top(p2);
 134         bn_check_top(m);
 135
 136         if (!(m->d[0] & 1))
 137                 {
 138                 BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
 139                 return(0);
 140                 }
 141         bits1=BN_num_bits(p1);
 142         bits2=BN_num_bits(p2);
 143         if ((bits1 == 0) && (bits2 == 0))
 144                 {
 145                 ret = BN_one(rr);
 146                 return ret;
 147                 }
 148
 149         bits=(bits1 > bits2)?bits1:bits2;
 150
 151         BN_CTX_start(ctx);
 152         d = BN_CTX_get(ctx);
 153         r = BN_CTX_get(ctx);
 154         val1[0] = BN_CTX_get(ctx);
 155         val2[0] = BN_CTX_get(ctx);
 156         if(!d || !r || !val1[0] || !val2[0]) goto err;
 157
 158         if (in_mont != NULL)
 159                 mont=in_mont;
 160         else
 161                 {
 162                 if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
 163                 if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
 164                 }
 165
 166         window1 = BN_window_bits_for_exponent_size(bits1);
 167         window2 = BN_window_bits_for_exponent_size(bits2);
 168
 169         /*
 170          * Build table for a1:   val1[i] := a1^(2*i + 1) mod m  for i = 0 .. 2^(window1-1)
 171          */
 172         if (a1->neg || BN_ucmp(a1,m) >= 0)
 173                 {
 174                 if (!BN_mod(val1[0],a1,m,ctx))
 175                         goto err;
 176                 a_mod_m = val1[0];
 177                 }
 178         else
 179                 a_mod_m = a1;
 180         if (BN_is_zero(a_mod_m))
 181                 {
 182                 BN_zero(rr);
 183                 ret = 1;
 184                 goto err;
 185                 }
 186
 187         if (!BN_to_montgomery(val1[0],a_mod_m,mont,ctx)) goto err;
 188         if (window1 > 1)
 189                 {
 190                 if (!BN_mod_mul_montgomery(d,val1[0],val1[0],mont,ctx)) goto err;
 191
 192                 j=1<<(window1-1);
 193                 for (i=1; i<j; i++)
 194                         {
 195                         if(((val1[i] = BN_CTX_get(ctx)) == NULL) ||
 196                                         !BN_mod_mul_montgomery(val1[i],val1[i-1],
 197                                                 d,mont,ctx))
 198                                 goto err;
 199                         }
 200                 }
 201
 202
 203         /*
 204          * Build table for a2:   val2[i] := a2^(2*i + 1) mod m  for i = 0 .. 2^(window2-1)
 205          */
 206         if (a2->neg || BN_ucmp(a2,m) >= 0)
 207                 {
 208                 if (!BN_mod(val2[0],a2,m,ctx))
 209                         goto err;
 210                 a_mod_m = val2[0];
 211                 }
 212         else
 213                 a_mod_m = a2;
 214         if (BN_is_zero(a_mod_m))
 215                 {
 216                 BN_zero(rr);
 217                 ret = 1;
 218                 goto err;
 219                 }
 220         if (!BN_to_montgomery(val2[0],a_mod_m,mont,ctx)) goto err;
 221         if (window2 > 1)
 222                 {
 223                 if (!BN_mod_mul_montgomery(d,val2[0],val2[0],mont,ctx)) goto err;
 224
 225                 j=1<<(window2-1);
 226                 for (i=1; i<j; i++)
 227                         {
 228                         if(((val2[i] = BN_CTX_get(ctx)) == NULL) ||
 229                                         !BN_mod_mul_montgomery(val2[i],val2[i-1],
 230                                                 d,mont,ctx))
 231                                 goto err;
 232                         }
 233                 }
 234
 235
 236         /* Now compute the power product, using independent windows. */
 237         r_is_one=1;
 238         wvalue1=0;  /* The 'value' of the first window */
 239         wvalue2=0;  /* The 'value' of the second window */
 240         wpos1=0;    /* If wvalue1 > 0, the bottom bit of the first window */
 241         wpos2=0;    /* If wvalue2 > 0, the bottom bit of the second window */
 242
 243         if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
 244         for (b=bits-1; b>=0; b--)
 245                 {
 246                 if (!r_is_one)
 247                         {
 248                         if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
 249                                 goto err;
 250                         }
 251
 252                 if (!wvalue1)
 253                         if (BN_is_bit_set(p1, b))
 254                                 {
 255                                 /* consider bits b-window1+1 .. b for this window */
 256                                 i = b-window1+1;
 257                                 while (!BN_is_bit_set(p1, i)) /* works for i<0 */
 258                                         i++;
 259                                 wpos1 = i;
 260                                 wvalue1 = 1;
 261                                 for (i = b-1; i >= wpos1; i--)
 262                                         {
 263                                         wvalue1 <<= 1;
 264                                         if (BN_is_bit_set(p1, i))
 265                                                 wvalue1++;
 266                                         }
 267                                 }
 268
 269                 if (!wvalue2)
 270                         if (BN_is_bit_set(p2, b))
 271                                 {
 272                                 /* consider bits b-window2+1 .. b for this window */
 273                                 i = b-window2+1;
 274                                 while (!BN_is_bit_set(p2, i))
 275                                         i++;
 276                                 wpos2 = i;
 277                                 wvalue2 = 1;
 278                                 for (i = b-1; i >= wpos2; i--)
 279                                         {
 280                                         wvalue2 <<= 1;
 281                                         if (BN_is_bit_set(p2, i))
 282                                                 wvalue2++;
 283                                         }
 284                                 }
 285
 286                 if (wvalue1 && b == wpos1)
 287                         {
 288                         /* wvalue1 is odd and < 2^window1 */
 289                         if (!BN_mod_mul_montgomery(r,r,val1[wvalue1>>1],mont,ctx))
 290                                 goto err;
 291                         wvalue1 = 0;
 292                         r_is_one = 0;
 293                         }
 294
 295                 if (wvalue2 && b == wpos2)
 296                         {
 297                         /* wvalue2 is odd and < 2^window2 */
 298                         if (!BN_mod_mul_montgomery(r,r,val2[wvalue2>>1],mont,ctx))
 299                                 goto err;
 300                         wvalue2 = 0;
 301                         r_is_one = 0;
 302                         }
 303                 }
 304         BN_from_montgomery(rr,r,mont,ctx);
 305         ret=1;
 306 err:
 307         if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
 308         BN_CTX_end(ctx);
 309         bn_check_top(rr);
 310         return(ret);
 311         }