1178479Sjb/* crypto/bn/bn_mont.c */ 2178479Sjb/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 3178479Sjb * All rights reserved. 4178479Sjb * 5210767Srpaulo * This package is an SSL implementation written 6210767Srpaulo * by Eric Young (eay@cryptsoft.com). 7178479Sjb * The implementation was written so as to conform with Netscapes SSL. 8178479Sjb * 9178479Sjb * This library is free for commercial and non-commercial use as long as 10178479Sjb * the following conditions are aheared to. The following conditions 11178479Sjb * apply to all code found in this distribution, be it the RC4, RSA, 12178479Sjb * lhash, DES, etc., code; not just the SSL code. The SSL documentation 13178479Sjb * included with this distribution is covered by the same copyright terms 14178479Sjb * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15178479Sjb * 16178479Sjb * Copyright remains Eric Young's, and as such any Copyright notices in 17178479Sjb * the code are not to be removed. 18178479Sjb * If this package is used in a product, Eric Young should be given attribution 19178479Sjb * as the author of the parts of the library used. 20178479Sjb * This can be in the form of a textual message at program startup or 21178479Sjb * in documentation (online or textual) provided with the package. 22210767Srpaulo * 23269245Smarkj * Redistribution and use in source and binary forms, with or without 24178479Sjb * modification, are permitted provided that the following conditions 25178479Sjb * are met: 26178479Sjb * 1. Redistributions of source code must retain the copyright 27178479Sjb * notice, this list of conditions and the following disclaimer. 28178479Sjb * 2. Redistributions in binary form must reproduce the above copyright 29178479Sjb * notice, this list of conditions and the following disclaimer in the 30178479Sjb * documentation and/or other materials provided with the distribution. 31178479Sjb * 3. All advertising materials mentioning features or use of this software 32178479Sjb * must display the following acknowledgement: 33178479Sjb * "This product includes cryptographic software written by 34178479Sjb * Eric Young (eay@cryptsoft.com)" 35178479Sjb * The word 'cryptographic' can be left out if the rouines from the library 36178479Sjb * being used are not cryptographic related :-). 37178479Sjb * 4. If you include any Windows specific code (or a derivative thereof) from 38211554Srpaulo * the apps directory (application code) you must include an acknowledgement: 39211554Srpaulo * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40178479Sjb * 41178479Sjb * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 42178479Sjb * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 43178479Sjb * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 44178479Sjb * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 45178479Sjb * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 46178479Sjb * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 47178479Sjb * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 48178479Sjb * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 49178479Sjb * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 50178479Sjb * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 51178479Sjb * SUCH DAMAGE. 52178479Sjb * 53178479Sjb * The licence and distribution terms for any publically available version or 54178479Sjb * derivative of this code cannot be changed. i.e. this code cannot simply be 55178479Sjb * copied and put under another distribution licence 56178479Sjb * [including the GNU Public Licence.] 57178479Sjb */ 58178572Sjb/* ==================================================================== 59211554Srpaulo * Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved. 60178479Sjb * 61211554Srpaulo * Redistribution and use in source and binary forms, with or without 62178479Sjb * modification, are permitted provided that the following conditions 63178479Sjb * are met: 64178479Sjb * 65211554Srpaulo * 1. Redistributions of source code must retain the above copyright 66178479Sjb * notice, this list of conditions and the following disclaimer. 67211554Srpaulo * 68212462Srpaulo * 2. Redistributions in binary form must reproduce the above copyright 69178479Sjb * notice, this list of conditions and the following disclaimer in 70178479Sjb * the documentation and/or other materials provided with the 71178479Sjb * distribution. 72178479Sjb * 73178479Sjb * 3. All advertising materials mentioning features or use of this 74178479Sjb * software must display the following acknowledgment: 75210767Srpaulo * "This product includes software developed by the OpenSSL Project 76178479Sjb * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 77178479Sjb * 78178479Sjb * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 79178479Sjb * endorse or promote products derived from this software without 80178479Sjb * prior written permission. For written permission, please contact 81178479Sjb * openssl-core@openssl.org. 82178479Sjb * 83178479Sjb * 5. Products derived from this software may not be called "OpenSSL" 84178479Sjb * nor may "OpenSSL" appear in their names without prior written 85178479Sjb * permission of the OpenSSL Project. 86178479Sjb * 87178479Sjb * 6. Redistributions of any form whatsoever must retain the following 88178479Sjb * acknowledgment: 89178479Sjb * "This product includes software developed by the OpenSSL Project 90178479Sjb * for use in the OpenSSL Toolkit (http://www.openssl.org/)" 91178479Sjb * 92178479Sjb * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 93211554Srpaulo * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 94211554Srpaulo * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 95211554Srpaulo * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 96211554Srpaulo * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 97211554Srpaulo * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 98211554Srpaulo * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 99211554Srpaulo * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 100211554Srpaulo * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 101211554Srpaulo * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 102211554Srpaulo * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 103211554Srpaulo * OF THE POSSIBILITY OF SUCH DAMAGE. 104211554Srpaulo * ==================================================================== 105211554Srpaulo * 106228547Sdim * This product includes cryptographic software written by Eric Young 107211554Srpaulo * (eay@cryptsoft.com). This product includes software written by Tim 108211554Srpaulo * Hudson (tjh@cryptsoft.com). 109211554Srpaulo * 110211554Srpaulo */ 111211554Srpaulo 112211554Srpaulo/* 113211554Srpaulo * Details about Montgomery multiplication algorithms can be found at 114211554Srpaulo * http://security.ece.orst.edu/publications.html, e.g. 115211554Srpaulo * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and 116211554Srpaulo * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf 117211554Srpaulo */ 118211554Srpaulo 119211554Srpaulo#include <stdio.h> 120211554Srpaulo#include "cryptlib.h" 121211554Srpaulo#include "bn_lcl.h" 122211554Srpaulo 123178572Sjb#define MONT_WORD /* use the faster word-based algorithm */ 124178479Sjb 125178572Sjb#ifdef MONT_WORD 126178572Sjbstatic int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont); 127178572Sjb#endif 128178572Sjb 129178479Sjbint BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, 130178479Sjb BN_MONT_CTX *mont, BN_CTX *ctx) 131178479Sjb { 132211554Srpaulo BIGNUM *tmp; 133178479Sjb int ret=0; 134211554Srpaulo#if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD) 135211554Srpaulo int num = mont->N.top; 136211554Srpaulo 137178479Sjb if (num>1 && a->top==num && b->top==num) 138178479Sjb { 139178479Sjb if (bn_wexpand(r,num) == NULL) return(0); 140178479Sjb if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,mont->n0,num)) 141178479Sjb { 142178479Sjb r->neg = a->neg^b->neg; 143211554Srpaulo r->top = num; 144178572Sjb bn_correct_top(r); 145178479Sjb return(1); 146178572Sjb } 147178572Sjb } 148269245Smarkj#endif 149269245Smarkj 150211554Srpaulo BN_CTX_start(ctx); 151178572Sjb tmp = BN_CTX_get(ctx); 152178479Sjb if (tmp == NULL) goto err; 153178479Sjb 154211554Srpaulo bn_check_top(tmp); 155211554Srpaulo if (a == b) 156211554Srpaulo { 157269245Smarkj if (!BN_sqr(tmp,a,ctx)) goto err; 158269245Smarkj } 159211554Srpaulo else 160211554Srpaulo { 161211554Srpaulo if (!BN_mul(tmp,a,b,ctx)) goto err; 162269245Smarkj } 163211554Srpaulo /* reduce from aRR to aR */ 164211554Srpaulo#ifdef MONT_WORD 165269245Smarkj if (!BN_from_montgomery_word(r,tmp,mont)) goto err; 166211554Srpaulo#else 167178479Sjb if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err; 168178479Sjb#endif 169178479Sjb bn_check_top(r); 170178479Sjb ret=1; 171210767Srpauloerr: 172210767Srpaulo BN_CTX_end(ctx); 173210767Srpaulo return(ret); 174178479Sjb } 175178479Sjb 176178479Sjb#ifdef MONT_WORD 177178479Sjbstatic int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont) 178178479Sjb { 179178572Sjb BIGNUM *n; 180178479Sjb BN_ULONG *ap,*np,*rp,n0,v,carry; 181178479Sjb int nl,max,i; 182178479Sjb 183178479Sjb n= &(mont->N); 184178572Sjb nl=n->top; 185178479Sjb if (nl == 0) { ret->top=0; return(1); } 186211554Srpaulo 187178479Sjb max=(2*nl); /* carry is stored separately */ 188178479Sjb if (bn_wexpand(r,max) == NULL) return(0); 189178479Sjb 190178479Sjb r->neg^=n->neg; 191211554Srpaulo np=n->d; 192211554Srpaulo rp=r->d; 193211554Srpaulo 194211554Srpaulo /* clear the top words of T */ 195211554Srpaulo#if 1 196211554Srpaulo for (i=r->top; i<max; i++) /* memset? XXX */ 197211554Srpaulo rp[i]=0; 198211554Srpaulo#else 199211554Srpaulo memset(&(rp[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); 200211554Srpaulo#endif 201211554Srpaulo 202211554Srpaulo r->top=max; 203211554Srpaulo n0=mont->n0[0]; 204211554Srpaulo 205211554Srpaulo#ifdef BN_COUNT 206211554Srpaulo fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl); 207211554Srpaulo#endif 208211554Srpaulo for (carry=0, i=0; i<nl; i++, rp++) 209211554Srpaulo { 210211554Srpaulo#ifdef __TANDEM 211211554Srpaulo { 212211554Srpaulo long long t1; 213211554Srpaulo long long t2; 214211554Srpaulo long long t3; 215269245Smarkj t1 = rp[0] * (n0 & 0177777); 216269245Smarkj t2 = 037777600000l; 217211554Srpaulo t2 = n0 & t2; 218211554Srpaulo t3 = rp[0] & 0177777; 219211554Srpaulo t2 = (t3 * t2) & BN_MASK2; 220211554Srpaulo t1 = t1 + t2; 221211554Srpaulo v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1); 222211554Srpaulo } 223211554Srpaulo#else 224211554Srpaulo v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2); 225211554Srpaulo#endif 226269245Smarkj v = (v+carry+rp[nl])&BN_MASK2; 227269245Smarkj carry |= (v != rp[nl]); 228269245Smarkj carry &= (v <= rp[nl]); 229269245Smarkj rp[nl]=v; 230211554Srpaulo } 231178479Sjb 232178479Sjb if (bn_wexpand(ret,nl) == NULL) return(0); 233178479Sjb ret->top=nl; 234178479Sjb ret->neg=r->neg; 235178479Sjb 236178479Sjb rp=ret->d; 237178479Sjb ap=&(r->d[nl]); 238178479Sjb 239178479Sjb#define BRANCH_FREE 1 240178479Sjb#if BRANCH_FREE 241178479Sjb { 242178479Sjb BN_ULONG *nrp; 243178572Sjb size_t m; 244178479Sjb 245178479Sjb v=bn_sub_words(rp,ap,np,nl)-carry; 246178479Sjb /* if subtraction result is real, then 247178479Sjb * trick unconditional memcpy below to perform in-place 248178479Sjb * "refresh" instead of actual copy. */ 249178479Sjb m=(0-(size_t)v); 250178479Sjb nrp=(BN_ULONG *)(((PTR_SIZE_INT)rp&~m)|((PTR_SIZE_INT)ap&m)); 251178479Sjb 252178479Sjb for (i=0,nl-=4; i<nl; i+=4) 253178479Sjb { 254178572Sjb BN_ULONG t1,t2,t3,t4; 255178479Sjb 256178572Sjb t1=nrp[i+0]; 257178572Sjb t2=nrp[i+1]; 258211554Srpaulo t3=nrp[i+2]; ap[i+0]=0; 259178479Sjb t4=nrp[i+3]; ap[i+1]=0; 260178479Sjb rp[i+0]=t1; ap[i+2]=0; 261178479Sjb rp[i+1]=t2; ap[i+3]=0; 262178479Sjb rp[i+2]=t3; 263178479Sjb rp[i+3]=t4; 264178479Sjb } 265178479Sjb for (nl+=4; i<nl; i++) 266178572Sjb rp[i]=nrp[i], ap[i]=0; 267178479Sjb } 268178572Sjb#else 269178572Sjb if (bn_sub_words (rp,ap,np,nl)-carry) 270178479Sjb memcpy(rp,ap,nl*sizeof(BN_ULONG)); 271178479Sjb#endif 272211554Srpaulo bn_correct_top(r); 273211554Srpaulo bn_correct_top(ret); 274211554Srpaulo bn_check_top(ret); 275178479Sjb 276211554Srpaulo return(1); 277211554Srpaulo } 278211554Srpaulo#endif /* MONT_WORD */ 279211554Srpaulo 280211554Srpauloint BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont, 281211554Srpaulo BN_CTX *ctx) 282211554Srpaulo { 283211554Srpaulo int retn=0; 284211554Srpaulo#ifdef MONT_WORD 285211554Srpaulo BIGNUM *t; 286211554Srpaulo 287211554Srpaulo BN_CTX_start(ctx); 288211554Srpaulo if ((t = BN_CTX_get(ctx)) && BN_copy(t,a)) 289211554Srpaulo retn = BN_from_montgomery_word(ret,t,mont); 290211554Srpaulo BN_CTX_end(ctx); 291211554Srpaulo#else /* !MONT_WORD */ 292211554Srpaulo BIGNUM *t1,*t2; 293211554Srpaulo 294211554Srpaulo BN_CTX_start(ctx); 295211554Srpaulo t1 = BN_CTX_get(ctx); 296211554Srpaulo t2 = BN_CTX_get(ctx); 297211554Srpaulo if (t1 == NULL || t2 == NULL) goto err; 298211554Srpaulo 299211554Srpaulo if (!BN_copy(t1,a)) goto err; 300211554Srpaulo BN_mask_bits(t1,mont->ri); 301269245Smarkj 302211554Srpaulo if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err; 303211554Srpaulo BN_mask_bits(t2,mont->ri); 304269245Smarkj 305269245Smarkj if (!BN_mul(t1,t2,&mont->N,ctx)) goto err; 306269245Smarkj if (!BN_add(t2,a,t1)) goto err; 307269245Smarkj if (!BN_rshift(ret,t2,mont->ri)) goto err; 308269245Smarkj 309269245Smarkj if (BN_ucmp(ret, &(mont->N)) >= 0) 310269245Smarkj { 311269245Smarkj if (!BN_usub(ret,ret,&(mont->N))) goto err; 312269245Smarkj } 313269245Smarkj retn=1; 314211554Srpaulo bn_check_top(ret); 315269245Smarkj err: 316269245Smarkj BN_CTX_end(ctx); 317269245Smarkj#endif /* MONT_WORD */ 318269245Smarkj return(retn); 319269245Smarkj } 320269245Smarkj 321269245SmarkjBN_MONT_CTX *BN_MONT_CTX_new(void) 322269245Smarkj { 323269245Smarkj BN_MONT_CTX *ret; 324269245Smarkj 325269245Smarkj if ((ret=(BN_MONT_CTX *)OPENSSL_malloc(sizeof(BN_MONT_CTX))) == NULL) 326269245Smarkj return(NULL); 327269245Smarkj 328269245Smarkj BN_MONT_CTX_init(ret); 329269245Smarkj ret->flags=BN_FLG_MALLOCED; 330269245Smarkj return(ret); 331269245Smarkj } 332269245Smarkj 333269245Smarkjvoid BN_MONT_CTX_init(BN_MONT_CTX *ctx) 334269245Smarkj { 335269245Smarkj ctx->ri=0; 336269245Smarkj BN_init(&(ctx->RR)); 337269245Smarkj BN_init(&(ctx->N)); 338269245Smarkj BN_init(&(ctx->Ni)); 339269245Smarkj ctx->n0[0] = ctx->n0[1] = 0; 340269245Smarkj ctx->flags=0; 341269245Smarkj } 342269245Smarkj 343269245Smarkjvoid BN_MONT_CTX_free(BN_MONT_CTX *mont) 344211554Srpaulo { 345211554Srpaulo if(mont == NULL) 346178479Sjb return; 347178479Sjb 348211554Srpaulo BN_free(&(mont->RR)); 349178479Sjb BN_free(&(mont->N)); 350211554Srpaulo BN_free(&(mont->Ni)); 351211554Srpaulo if (mont->flags & BN_FLG_MALLOCED) 352211554Srpaulo OPENSSL_free(mont); 353211554Srpaulo } 354178479Sjb 355178479Sjbint BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx) 356269245Smarkj { 357211554Srpaulo int ret = 0; 358269245Smarkj BIGNUM *Ri,*R; 359269245Smarkj 360269245Smarkj BN_CTX_start(ctx); 361269245Smarkj if((Ri = BN_CTX_get(ctx)) == NULL) goto err; 362211554Srpaulo R= &(mont->RR); /* grab RR as a temp */ 363211554Srpaulo if (!BN_copy(&(mont->N),mod)) goto err; /* Set N */ 364211554Srpaulo mont->N.neg = 0; 365178479Sjb 366178479Sjb#ifdef MONT_WORD 367178572Sjb { 368178479Sjb BIGNUM tmod; 369178572Sjb BN_ULONG buf[2]; 370178572Sjb 371178572Sjb BN_init(&tmod); 372178572Sjb tmod.d=buf; 373178479Sjb tmod.dmax=2; 374178479Sjb tmod.neg=0; 375178479Sjb 376178479Sjb mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2; 377178479Sjb 378178572Sjb#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32) 379178572Sjb /* Only certain BN_BITS2<=32 platforms actually make use of 380178479Sjb * n0[1], and we could use the #else case (with a shorter R 381178479Sjb * value) for the others. However, currently only the assembler 382178479Sjb * files do know which is which. */ 383211554Srpaulo 384178479Sjb BN_zero(R); 385178479Sjb if (!(BN_set_bit(R,2*BN_BITS2))) goto err; 386178479Sjb 387178479Sjb tmod.top=0; 388178479Sjb if ((buf[0] = mod->d[0])) tmod.top=1; 389178479Sjb if ((buf[1] = mod->top>1 ? mod->d[1] : 0)) tmod.top=2; 390 391 if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL) 392 goto err; 393 if (!BN_lshift(Ri,Ri,2*BN_BITS2)) goto err; /* R*Ri */ 394 if (!BN_is_zero(Ri)) 395 { 396 if (!BN_sub_word(Ri,1)) goto err; 397 } 398 else /* if N mod word size == 1 */ 399 { 400 if (bn_expand(Ri,(int)sizeof(BN_ULONG)*2) == NULL) 401 goto err; 402 /* Ri-- (mod double word size) */ 403 Ri->neg=0; 404 Ri->d[0]=BN_MASK2; 405 Ri->d[1]=BN_MASK2; 406 Ri->top=2; 407 } 408 if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err; 409 /* Ni = (R*Ri-1)/N, 410 * keep only couple of least significant words: */ 411 mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0; 412 mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0; 413#else 414 BN_zero(R); 415 if (!(BN_set_bit(R,BN_BITS2))) goto err; /* R */ 416 417 buf[0]=mod->d[0]; /* tmod = N mod word size */ 418 buf[1]=0; 419 tmod.top = buf[0] != 0 ? 1 : 0; 420 /* Ri = R^-1 mod N*/ 421 if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL) 422 goto err; 423 if (!BN_lshift(Ri,Ri,BN_BITS2)) goto err; /* R*Ri */ 424 if (!BN_is_zero(Ri)) 425 { 426 if (!BN_sub_word(Ri,1)) goto err; 427 } 428 else /* if N mod word size == 1 */ 429 { 430 if (!BN_set_word(Ri,BN_MASK2)) goto err; /* Ri-- (mod word size) */ 431 } 432 if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err; 433 /* Ni = (R*Ri-1)/N, 434 * keep only least significant word: */ 435 mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0; 436 mont->n0[1] = 0; 437#endif 438 } 439#else /* !MONT_WORD */ 440 { /* bignum version */ 441 mont->ri=BN_num_bits(&mont->N); 442 BN_zero(R); 443 if (!BN_set_bit(R,mont->ri)) goto err; /* R = 2^ri */ 444 /* Ri = R^-1 mod N*/ 445 if ((BN_mod_inverse(Ri,R,&mont->N,ctx)) == NULL) 446 goto err; 447 if (!BN_lshift(Ri,Ri,mont->ri)) goto err; /* R*Ri */ 448 if (!BN_sub_word(Ri,1)) goto err; 449 /* Ni = (R*Ri-1) / N */ 450 if (!BN_div(&(mont->Ni),NULL,Ri,&mont->N,ctx)) goto err; 451 } 452#endif 453 454 /* setup RR for conversions */ 455 BN_zero(&(mont->RR)); 456 if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err; 457 if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err; 458 459 ret = 1; 460err: 461 BN_CTX_end(ctx); 462 return ret; 463 } 464 465BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from) 466 { 467 if (to == from) return(to); 468 469 if (!BN_copy(&(to->RR),&(from->RR))) return NULL; 470 if (!BN_copy(&(to->N),&(from->N))) return NULL; 471 if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL; 472 to->ri=from->ri; 473 to->n0[0]=from->n0[0]; 474 to->n0[1]=from->n0[1]; 475 return(to); 476 } 477 478BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, int lock, 479 const BIGNUM *mod, BN_CTX *ctx) 480 { 481 BN_MONT_CTX *ret; 482 483 CRYPTO_r_lock(lock); 484 ret = *pmont; 485 CRYPTO_r_unlock(lock); 486 if (ret) 487 return ret; 488 489 /* We don't want to serialise globally while doing our lazy-init math in 490 * BN_MONT_CTX_set. That punishes threads that are doing independent 491 * things. Instead, punish the case where more than one thread tries to 492 * lazy-init the same 'pmont', by having each do the lazy-init math work 493 * independently and only use the one from the thread that wins the race 494 * (the losers throw away the work they've done). */ 495 ret = BN_MONT_CTX_new(); 496 if (!ret) 497 return NULL; 498 if (!BN_MONT_CTX_set(ret, mod, ctx)) 499 { 500 BN_MONT_CTX_free(ret); 501 return NULL; 502 } 503 504 /* The locked compare-and-set, after the local work is done. */ 505 CRYPTO_w_lock(lock); 506 if (*pmont) 507 { 508 BN_MONT_CTX_free(ret); 509 ret = *pmont; 510 } 511 else 512 *pmont = ret; 513 CRYPTO_w_unlock(lock); 514 return ret; 515 } 516