bn_exp2.c revision 68651
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 118int BN_mod_exp2_mont(BIGNUM *rr, BIGNUM *a1, BIGNUM *p1, BIGNUM *a2, 119 BIGNUM *p2, BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont) 120 { 121 int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2; 122 int r_is_one=1,ts1=0,ts2=0; 123 BIGNUM *d,*r; 124 BIGNUM *a_mod_m; 125 BIGNUM val1[TABLE_SIZE], val2[TABLE_SIZE]; 126 BN_MONT_CTX *mont=NULL; 127 128 bn_check_top(a1); 129 bn_check_top(p1); 130 bn_check_top(a2); 131 bn_check_top(p2); 132 bn_check_top(m); 133 134 if (!(m->d[0] & 1)) 135 { 136 BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS); 137 return(0); 138 } 139 bits1=BN_num_bits(p1); 140 bits2=BN_num_bits(p2); 141 if ((bits1 == 0) && (bits2 == 0)) 142 { 143 BN_one(rr); 144 return(1); 145 } 146 bits=(bits1 > bits2)?bits1:bits2; 147 148 BN_CTX_start(ctx); 149 d = BN_CTX_get(ctx); 150 r = BN_CTX_get(ctx); 151 if (d == NULL || r == NULL) goto err; 152 153 if (in_mont != NULL) 154 mont=in_mont; 155 else 156 { 157 if ((mont=BN_MONT_CTX_new()) == NULL) goto err; 158 if (!BN_MONT_CTX_set(mont,m,ctx)) goto err; 159 } 160 161 window1 = BN_window_bits_for_exponent_size(bits1); 162 window2 = BN_window_bits_for_exponent_size(bits2); 163 164 /* 165 * Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1) 166 */ 167 BN_init(&val1[0]); 168 ts1=1; 169 if (BN_ucmp(a1,m) >= 0) 170 { 171 if (!BN_mod(&(val1[0]),a1,m,ctx)) 172 goto err; 173 a_mod_m = &(val1[0]); 174 } 175 else 176 a_mod_m = a1; 177 if (!BN_to_montgomery(&(val1[0]),a_mod_m,mont,ctx)) goto err; 178 if (window1 > 1) 179 { 180 if (!BN_mod_mul_montgomery(d,&(val1[0]),&(val1[0]),mont,ctx)) goto err; 181 182 j=1<<(window1-1); 183 for (i=1; i<j; i++) 184 { 185 BN_init(&(val1[i])); 186 if (!BN_mod_mul_montgomery(&(val1[i]),&(val1[i-1]),d,mont,ctx)) 187 goto err; 188 } 189 ts1=i; 190 } 191 192 193 /* 194 * Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1) 195 */ 196 BN_init(&val2[0]); 197 ts2=1; 198 if (BN_ucmp(a2,m) >= 0) 199 { 200 if (!BN_mod(&(val2[0]),a2,m,ctx)) 201 goto err; 202 a_mod_m = &(val2[0]); 203 } 204 else 205 a_mod_m = a2; 206 if (!BN_to_montgomery(&(val2[0]),a_mod_m,mont,ctx)) goto err; 207 if (window2 > 1) 208 { 209 if (!BN_mod_mul_montgomery(d,&(val2[0]),&(val2[0]),mont,ctx)) goto err; 210 211 j=1<<(window2-1); 212 for (i=1; i<j; i++) 213 { 214 BN_init(&(val2[i])); 215 if (!BN_mod_mul_montgomery(&(val2[i]),&(val2[i-1]),d,mont,ctx)) 216 goto err; 217 } 218 ts2=i; 219 } 220 221 222 /* Now compute the power product, using independent windows. */ 223 r_is_one=1; 224 wvalue1=0; /* The 'value' of the first window */ 225 wvalue2=0; /* The 'value' of the second window */ 226 wpos1=0; /* If wvalue1 > 0, the bottom bit of the first window */ 227 wpos2=0; /* If wvalue2 > 0, the bottom bit of the second window */ 228 229 if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err; 230 for (b=bits-1; b>=0; b--) 231 { 232 if (!r_is_one) 233 { 234 if (!BN_mod_mul_montgomery(r,r,r,mont,ctx)) 235 goto err; 236 } 237 238 if (!wvalue1) 239 if (BN_is_bit_set(p1, b)) 240 { 241 /* consider bits b-window1+1 .. b for this window */ 242 i = b-window1+1; 243 while (!BN_is_bit_set(p1, i)) /* works for i<0 */ 244 i++; 245 wpos1 = i; 246 wvalue1 = 1; 247 for (i = b-1; i >= wpos1; i--) 248 { 249 wvalue1 <<= 1; 250 if (BN_is_bit_set(p1, i)) 251 wvalue1++; 252 } 253 } 254 255 if (!wvalue2) 256 if (BN_is_bit_set(p2, b)) 257 { 258 /* consider bits b-window2+1 .. b for this window */ 259 i = b-window2+1; 260 while (!BN_is_bit_set(p2, i)) 261 i++; 262 wpos2 = i; 263 wvalue2 = 1; 264 for (i = b-1; i >= wpos2; i--) 265 { 266 wvalue2 <<= 1; 267 if (BN_is_bit_set(p2, i)) 268 wvalue2++; 269 } 270 } 271 272 if (wvalue1 && b == wpos1) 273 { 274 /* wvalue1 is odd and < 2^window1 */ 275 if (!BN_mod_mul_montgomery(r,r,&(val1[wvalue1>>1]),mont,ctx)) 276 goto err; 277 wvalue1 = 0; 278 r_is_one = 0; 279 } 280 281 if (wvalue2 && b == wpos2) 282 { 283 /* wvalue2 is odd and < 2^window2 */ 284 if (!BN_mod_mul_montgomery(r,r,&(val2[wvalue2>>1]),mont,ctx)) 285 goto err; 286 wvalue2 = 0; 287 r_is_one = 0; 288 } 289 } 290 BN_from_montgomery(rr,r,mont,ctx); 291 ret=1; 292err: 293 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont); 294 BN_CTX_end(ctx); 295 for (i=0; i<ts1; i++) 296 BN_clear_free(&(val1[i])); 297 for (i=0; i<ts2; i++) 298 BN_clear_free(&(val2[i])); 299 return(ret); 300 } 301