Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 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 | } |