Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 1 | /* crypto/bn/bn_mont.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) 1998-2006 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 | /* |
| 113 | * Details about Montgomery multiplication algorithms can be found at |
| 114 | * http://security.ece.orst.edu/publications.html, e.g. |
| 115 | * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and |
| 116 | * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf |
| 117 | */ |
| 118 | |
| 119 | #include <stdio.h> |
| 120 | #include "cryptlib.h" |
| 121 | #include "bn_lcl.h" |
| 122 | |
| 123 | #define MONT_WORD /* use the faster word-based algorithm */ |
| 124 | |
| 125 | #ifdef MONT_WORD |
| 126 | static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont); |
| 127 | #endif |
| 128 | |
| 129 | int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, |
| 130 | BN_MONT_CTX *mont, BN_CTX *ctx) |
| 131 | { |
| 132 | BIGNUM *tmp; |
| 133 | int ret=0; |
| 134 | #if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD) |
| 135 | int num = mont->N.top; |
| 136 | |
| 137 | if (num>1 && a->top==num && b->top==num) |
| 138 | { |
| 139 | if (bn_wexpand(r,num) == NULL) return(0); |
| 140 | if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,mont->n0,num)) |
| 141 | { |
| 142 | r->neg = a->neg^b->neg; |
| 143 | r->top = num; |
| 144 | bn_correct_top(r); |
| 145 | return(1); |
| 146 | } |
| 147 | } |
| 148 | #endif |
| 149 | |
| 150 | BN_CTX_start(ctx); |
| 151 | tmp = BN_CTX_get(ctx); |
| 152 | if (tmp == NULL) goto err; |
| 153 | |
| 154 | bn_check_top(tmp); |
| 155 | if (a == b) |
| 156 | { |
| 157 | if (!BN_sqr(tmp,a,ctx)) goto err; |
| 158 | } |
| 159 | else |
| 160 | { |
| 161 | if (!BN_mul(tmp,a,b,ctx)) goto err; |
| 162 | } |
| 163 | /* reduce from aRR to aR */ |
| 164 | #ifdef MONT_WORD |
| 165 | if (!BN_from_montgomery_word(r,tmp,mont)) goto err; |
| 166 | #else |
| 167 | if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err; |
| 168 | #endif |
| 169 | bn_check_top(r); |
| 170 | ret=1; |
| 171 | err: |
| 172 | BN_CTX_end(ctx); |
| 173 | return(ret); |
| 174 | } |
| 175 | |
| 176 | #ifdef MONT_WORD |
| 177 | static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont) |
| 178 | { |
| 179 | BIGNUM *n; |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 180 | BN_ULONG *ap,*np,*rp,n0,v,*nrp; |
| 181 | int al,nl,max,i,x,ri; |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 182 | |
| 183 | n= &(mont->N); |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 184 | /* mont->ri is the size of mont->N in bits (rounded up |
| 185 | to the word size) */ |
| 186 | al=ri=mont->ri/BN_BITS2; |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 187 | |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 188 | nl=n->top; |
| 189 | if ((al == 0) || (nl == 0)) { ret->top=0; return(1); } |
| 190 | |
| 191 | max=(nl+al+1); /* allow for overflow (no?) XXX */ |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 192 | if (bn_wexpand(r,max) == NULL) return(0); |
| 193 | |
| 194 | r->neg^=n->neg; |
| 195 | np=n->d; |
| 196 | rp=r->d; |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 197 | nrp= &(r->d[nl]); |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 198 | |
| 199 | /* clear the top words of T */ |
| 200 | #if 1 |
| 201 | for (i=r->top; i<max; i++) /* memset? XXX */ |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 202 | r->d[i]=0; |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 203 | #else |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 204 | memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 205 | #endif |
| 206 | |
| 207 | r->top=max; |
| 208 | n0=mont->n0[0]; |
| 209 | |
| 210 | #ifdef BN_COUNT |
| 211 | fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl); |
| 212 | #endif |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 213 | for (i=0; i<nl; i++) |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 214 | { |
| 215 | #ifdef __TANDEM |
| 216 | { |
| 217 | long long t1; |
| 218 | long long t2; |
| 219 | long long t3; |
| 220 | t1 = rp[0] * (n0 & 0177777); |
| 221 | t2 = 037777600000l; |
| 222 | t2 = n0 & t2; |
| 223 | t3 = rp[0] & 0177777; |
| 224 | t2 = (t3 * t2) & BN_MASK2; |
| 225 | t1 = t1 + t2; |
| 226 | v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1); |
| 227 | } |
| 228 | #else |
| 229 | v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2); |
| 230 | #endif |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 231 | nrp++; |
| 232 | rp++; |
| 233 | if (((nrp[-1]+=v)&BN_MASK2) >= v) |
| 234 | continue; |
| 235 | else |
| 236 | { |
| 237 | if (((++nrp[0])&BN_MASK2) != 0) continue; |
| 238 | if (((++nrp[1])&BN_MASK2) != 0) continue; |
| 239 | for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ; |
| 240 | } |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 241 | } |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 242 | bn_correct_top(r); |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 243 | |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 244 | /* mont->ri will be a multiple of the word size and below code |
| 245 | * is kind of BN_rshift(ret,r,mont->ri) equivalent */ |
| 246 | if (r->top <= ri) |
| 247 | { |
| 248 | ret->top=0; |
| 249 | return(1); |
| 250 | } |
| 251 | al=r->top-ri; |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 252 | |
| 253 | #define BRANCH_FREE 1 |
| 254 | #if BRANCH_FREE |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 255 | if (bn_wexpand(ret,ri) == NULL) return(0); |
| 256 | x=0-(((al-ri)>>(sizeof(al)*8-1))&1); |
| 257 | ret->top=x=(ri&~x)|(al&x); /* min(ri,al) */ |
| 258 | ret->neg=r->neg; |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 259 | |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 260 | rp=ret->d; |
| 261 | ap=&(r->d[ri]); |
| 262 | |
| 263 | { |
| 264 | size_t m1,m2; |
| 265 | |
| 266 | v=bn_sub_words(rp,ap,np,ri); |
| 267 | /* this ----------------^^ works even in al<ri case |
| 268 | * thanks to zealous zeroing of top of the vector in the |
| 269 | * beginning. */ |
| 270 | |
| 271 | /* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */ |
| 272 | /* in other words if subtraction result is real, then |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 273 | * trick unconditional memcpy below to perform in-place |
| 274 | * "refresh" instead of actual copy. */ |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 275 | m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1); /* al<ri */ |
| 276 | m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1); /* al>ri */ |
| 277 | m1|=m2; /* (al!=ri) */ |
| 278 | m1|=(0-(size_t)v); /* (al!=ri || v) */ |
| 279 | m1&=~m2; /* (al!=ri || v) && !al>ri */ |
| 280 | nrp=(BN_ULONG *)(((PTR_SIZE_INT)rp&~m1)|((PTR_SIZE_INT)ap&m1)); |
| 281 | } |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 282 | |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 283 | /* 'i<ri' is chosen to eliminate dependency on input data, even |
| 284 | * though it results in redundant copy in al<ri case. */ |
| 285 | for (i=0,ri-=4; i<ri; i+=4) |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 286 | { |
| 287 | BN_ULONG t1,t2,t3,t4; |
| 288 | |
| 289 | t1=nrp[i+0]; |
| 290 | t2=nrp[i+1]; |
| 291 | t3=nrp[i+2]; ap[i+0]=0; |
| 292 | t4=nrp[i+3]; ap[i+1]=0; |
| 293 | rp[i+0]=t1; ap[i+2]=0; |
| 294 | rp[i+1]=t2; ap[i+3]=0; |
| 295 | rp[i+2]=t3; |
| 296 | rp[i+3]=t4; |
| 297 | } |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 298 | for (ri+=4; i<ri; i++) |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 299 | rp[i]=nrp[i], ap[i]=0; |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 300 | bn_correct_top(r); |
| 301 | bn_correct_top(ret); |
Alexandre Savard | 7541067 | 2012-08-08 09:50:01 -0400 | [diff] [blame] | 302 | #else |
| 303 | if (bn_wexpand(ret,al) == NULL) return(0); |
| 304 | ret->top=al; |
| 305 | ret->neg=r->neg; |
| 306 | |
| 307 | rp=ret->d; |
| 308 | ap=&(r->d[ri]); |
| 309 | al-=4; |
| 310 | for (i=0; i<al; i+=4) |
| 311 | { |
| 312 | BN_ULONG t1,t2,t3,t4; |
| 313 | |
| 314 | t1=ap[i+0]; |
| 315 | t2=ap[i+1]; |
| 316 | t3=ap[i+2]; |
| 317 | t4=ap[i+3]; |
| 318 | rp[i+0]=t1; |
| 319 | rp[i+1]=t2; |
| 320 | rp[i+2]=t3; |
| 321 | rp[i+3]=t4; |
| 322 | } |
| 323 | al+=4; |
| 324 | for (; i<al; i++) |
| 325 | rp[i]=ap[i]; |
| 326 | |
| 327 | if (BN_ucmp(ret, &(mont->N)) >= 0) |
| 328 | { |
| 329 | if (!BN_usub(ret,ret,&(mont->N))) return(0); |
| 330 | } |
| 331 | #endif |
Alexandre Savard | 1b09e31 | 2012-08-07 20:33:29 -0400 | [diff] [blame] | 332 | bn_check_top(ret); |
| 333 | |
| 334 | return(1); |
| 335 | } |
| 336 | #endif /* MONT_WORD */ |
| 337 | |
| 338 | int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont, |
| 339 | BN_CTX *ctx) |
| 340 | { |
| 341 | int retn=0; |
| 342 | #ifdef MONT_WORD |
| 343 | BIGNUM *t; |
| 344 | |
| 345 | BN_CTX_start(ctx); |
| 346 | if ((t = BN_CTX_get(ctx)) && BN_copy(t,a)) |
| 347 | retn = BN_from_montgomery_word(ret,t,mont); |
| 348 | BN_CTX_end(ctx); |
| 349 | #else /* !MONT_WORD */ |
| 350 | BIGNUM *t1,*t2; |
| 351 | |
| 352 | BN_CTX_start(ctx); |
| 353 | t1 = BN_CTX_get(ctx); |
| 354 | t2 = BN_CTX_get(ctx); |
| 355 | if (t1 == NULL || t2 == NULL) goto err; |
| 356 | |
| 357 | if (!BN_copy(t1,a)) goto err; |
| 358 | BN_mask_bits(t1,mont->ri); |
| 359 | |
| 360 | if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err; |
| 361 | BN_mask_bits(t2,mont->ri); |
| 362 | |
| 363 | if (!BN_mul(t1,t2,&mont->N,ctx)) goto err; |
| 364 | if (!BN_add(t2,a,t1)) goto err; |
| 365 | if (!BN_rshift(ret,t2,mont->ri)) goto err; |
| 366 | |
| 367 | if (BN_ucmp(ret, &(mont->N)) >= 0) |
| 368 | { |
| 369 | if (!BN_usub(ret,ret,&(mont->N))) goto err; |
| 370 | } |
| 371 | retn=1; |
| 372 | bn_check_top(ret); |
| 373 | err: |
| 374 | BN_CTX_end(ctx); |
| 375 | #endif /* MONT_WORD */ |
| 376 | return(retn); |
| 377 | } |
| 378 | |
| 379 | BN_MONT_CTX *BN_MONT_CTX_new(void) |
| 380 | { |
| 381 | BN_MONT_CTX *ret; |
| 382 | |
| 383 | if ((ret=(BN_MONT_CTX *)OPENSSL_malloc(sizeof(BN_MONT_CTX))) == NULL) |
| 384 | return(NULL); |
| 385 | |
| 386 | BN_MONT_CTX_init(ret); |
| 387 | ret->flags=BN_FLG_MALLOCED; |
| 388 | return(ret); |
| 389 | } |
| 390 | |
| 391 | void BN_MONT_CTX_init(BN_MONT_CTX *ctx) |
| 392 | { |
| 393 | ctx->ri=0; |
| 394 | BN_init(&(ctx->RR)); |
| 395 | BN_init(&(ctx->N)); |
| 396 | BN_init(&(ctx->Ni)); |
| 397 | ctx->n0[0] = ctx->n0[1] = 0; |
| 398 | ctx->flags=0; |
| 399 | } |
| 400 | |
| 401 | void BN_MONT_CTX_free(BN_MONT_CTX *mont) |
| 402 | { |
| 403 | if(mont == NULL) |
| 404 | return; |
| 405 | |
| 406 | BN_free(&(mont->RR)); |
| 407 | BN_free(&(mont->N)); |
| 408 | BN_free(&(mont->Ni)); |
| 409 | if (mont->flags & BN_FLG_MALLOCED) |
| 410 | OPENSSL_free(mont); |
| 411 | } |
| 412 | |
| 413 | int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx) |
| 414 | { |
| 415 | int ret = 0; |
| 416 | BIGNUM *Ri,*R; |
| 417 | |
| 418 | BN_CTX_start(ctx); |
| 419 | if((Ri = BN_CTX_get(ctx)) == NULL) goto err; |
| 420 | R= &(mont->RR); /* grab RR as a temp */ |
| 421 | if (!BN_copy(&(mont->N),mod)) goto err; /* Set N */ |
| 422 | mont->N.neg = 0; |
| 423 | |
| 424 | #ifdef MONT_WORD |
| 425 | { |
| 426 | BIGNUM tmod; |
| 427 | BN_ULONG buf[2]; |
| 428 | |
| 429 | BN_init(&tmod); |
| 430 | tmod.d=buf; |
| 431 | tmod.dmax=2; |
| 432 | tmod.neg=0; |
| 433 | |
| 434 | mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2; |
| 435 | |
| 436 | #if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32) |
| 437 | /* Only certain BN_BITS2<=32 platforms actually make use of |
| 438 | * n0[1], and we could use the #else case (with a shorter R |
| 439 | * value) for the others. However, currently only the assembler |
| 440 | * files do know which is which. */ |
| 441 | |
| 442 | BN_zero(R); |
| 443 | if (!(BN_set_bit(R,2*BN_BITS2))) goto err; |
| 444 | |
| 445 | tmod.top=0; |
| 446 | if ((buf[0] = mod->d[0])) tmod.top=1; |
| 447 | if ((buf[1] = mod->top>1 ? mod->d[1] : 0)) tmod.top=2; |
| 448 | |
| 449 | if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL) |
| 450 | goto err; |
| 451 | if (!BN_lshift(Ri,Ri,2*BN_BITS2)) goto err; /* R*Ri */ |
| 452 | if (!BN_is_zero(Ri)) |
| 453 | { |
| 454 | if (!BN_sub_word(Ri,1)) goto err; |
| 455 | } |
| 456 | else /* if N mod word size == 1 */ |
| 457 | { |
| 458 | if (bn_expand(Ri,(int)sizeof(BN_ULONG)*2) == NULL) |
| 459 | goto err; |
| 460 | /* Ri-- (mod double word size) */ |
| 461 | Ri->neg=0; |
| 462 | Ri->d[0]=BN_MASK2; |
| 463 | Ri->d[1]=BN_MASK2; |
| 464 | Ri->top=2; |
| 465 | } |
| 466 | if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err; |
| 467 | /* Ni = (R*Ri-1)/N, |
| 468 | * keep only couple of least significant words: */ |
| 469 | mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0; |
| 470 | mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0; |
| 471 | #else |
| 472 | BN_zero(R); |
| 473 | if (!(BN_set_bit(R,BN_BITS2))) goto err; /* R */ |
| 474 | |
| 475 | buf[0]=mod->d[0]; /* tmod = N mod word size */ |
| 476 | buf[1]=0; |
| 477 | tmod.top = buf[0] != 0 ? 1 : 0; |
| 478 | /* Ri = R^-1 mod N*/ |
| 479 | if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL) |
| 480 | goto err; |
| 481 | if (!BN_lshift(Ri,Ri,BN_BITS2)) goto err; /* R*Ri */ |
| 482 | if (!BN_is_zero(Ri)) |
| 483 | { |
| 484 | if (!BN_sub_word(Ri,1)) goto err; |
| 485 | } |
| 486 | else /* if N mod word size == 1 */ |
| 487 | { |
| 488 | if (!BN_set_word(Ri,BN_MASK2)) goto err; /* Ri-- (mod word size) */ |
| 489 | } |
| 490 | if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err; |
| 491 | /* Ni = (R*Ri-1)/N, |
| 492 | * keep only least significant word: */ |
| 493 | mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0; |
| 494 | mont->n0[1] = 0; |
| 495 | #endif |
| 496 | } |
| 497 | #else /* !MONT_WORD */ |
| 498 | { /* bignum version */ |
| 499 | mont->ri=BN_num_bits(&mont->N); |
| 500 | BN_zero(R); |
| 501 | if (!BN_set_bit(R,mont->ri)) goto err; /* R = 2^ri */ |
| 502 | /* Ri = R^-1 mod N*/ |
| 503 | if ((BN_mod_inverse(Ri,R,&mont->N,ctx)) == NULL) |
| 504 | goto err; |
| 505 | if (!BN_lshift(Ri,Ri,mont->ri)) goto err; /* R*Ri */ |
| 506 | if (!BN_sub_word(Ri,1)) goto err; |
| 507 | /* Ni = (R*Ri-1) / N */ |
| 508 | if (!BN_div(&(mont->Ni),NULL,Ri,&mont->N,ctx)) goto err; |
| 509 | } |
| 510 | #endif |
| 511 | |
| 512 | /* setup RR for conversions */ |
| 513 | BN_zero(&(mont->RR)); |
| 514 | if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err; |
| 515 | if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err; |
| 516 | |
| 517 | ret = 1; |
| 518 | err: |
| 519 | BN_CTX_end(ctx); |
| 520 | return ret; |
| 521 | } |
| 522 | |
| 523 | BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from) |
| 524 | { |
| 525 | if (to == from) return(to); |
| 526 | |
| 527 | if (!BN_copy(&(to->RR),&(from->RR))) return NULL; |
| 528 | if (!BN_copy(&(to->N),&(from->N))) return NULL; |
| 529 | if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL; |
| 530 | to->ri=from->ri; |
| 531 | to->n0[0]=from->n0[0]; |
| 532 | to->n0[1]=from->n0[1]; |
| 533 | return(to); |
| 534 | } |
| 535 | |
| 536 | BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, int lock, |
| 537 | const BIGNUM *mod, BN_CTX *ctx) |
| 538 | { |
| 539 | int got_write_lock = 0; |
| 540 | BN_MONT_CTX *ret; |
| 541 | |
| 542 | CRYPTO_r_lock(lock); |
| 543 | if (!*pmont) |
| 544 | { |
| 545 | CRYPTO_r_unlock(lock); |
| 546 | CRYPTO_w_lock(lock); |
| 547 | got_write_lock = 1; |
| 548 | |
| 549 | if (!*pmont) |
| 550 | { |
| 551 | ret = BN_MONT_CTX_new(); |
| 552 | if (ret && !BN_MONT_CTX_set(ret, mod, ctx)) |
| 553 | BN_MONT_CTX_free(ret); |
| 554 | else |
| 555 | *pmont = ret; |
| 556 | } |
| 557 | } |
| 558 | |
| 559 | ret = *pmont; |
| 560 | |
| 561 | if (got_write_lock) |
| 562 | CRYPTO_w_unlock(lock); |
| 563 | else |
| 564 | CRYPTO_r_unlock(lock); |
| 565 | |
| 566 | return ret; |
| 567 | } |