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 if (!BN_from_montgomery(rr,r,mont,ctx)) 305 goto err; 306 ret=1; 307 err: 308 if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont); 309 BN_CTX_end(ctx); 310 bn_check_top(rr); 311 return(ret); 312 } 313