AppleCSP/open_ssl/bn/bn_mont.c

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 /* crypto/bn/bn_mont.c */
  20 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  21  * All rights reserved.
  22  *
  23  * This package is an SSL implementation written
  24  * by Eric Young (eay@cryptsoft.com).
  25  * The implementation was written so as to conform with Netscapes SSL.
  26  *
  27  * This library is free for commercial and non-commercial use as long as
  28  * the following conditions are aheared to.  The following conditions
  29  * apply to all code found in this distribution, be it the RC4, RSA,
  30  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  31  * included with this distribution is covered by the same copyright terms
  32  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  33  *
  34  * Copyright remains Eric Young's, and as such any Copyright notices in
  35  * the code are not to be removed.
  36  * If this package is used in a product, Eric Young should be given attribution
  37  * as the author of the parts of the library used.
  38  * This can be in the form of a textual message at program startup or
  39  * in documentation (online or textual) provided with the package.
  40  *
  41  * Redistribution and use in source and binary forms, with or without
  42  * modification, are permitted provided that the following conditions
  43  * are met:
  44  * 1. Redistributions of source code must retain the copyright
  45  *    notice, this list of conditions and the following disclaimer.
  46  * 2. Redistributions in binary form must reproduce the above copyright
  47  *    notice, this list of conditions and the following disclaimer in the
  48  *    documentation and/or other materials provided with the distribution.
  49  * 3. All advertising materials mentioning features or use of this software
  50  *    must display the following acknowledgement:
  51  *    "This product includes cryptographic software written by
  52  *     Eric Young (eay@cryptsoft.com)"
  53  *    The word 'cryptographic' can be left out if the rouines from the library
  54  *    being used are not cryptographic related :-).
  55  * 4. If you include any Windows specific code (or a derivative thereof) from
  56  *    the apps directory (application code) you must include an acknowledgement:
  57  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  58  *
  59  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  60  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  61  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  62  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  63  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  64  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  65  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  66  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  67  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  68  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  69  * SUCH DAMAGE.
  70  *
  71  * The licence and distribution terms for any publically available version or
  72  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  73  * copied and put under another distribution licence
  74  * [including the GNU Public Licence.]
  75  */
  76
  77 /*
  78  * Details about Montgomery multiplication algorithms can be found at
  79  * http://security.ece.orst.edu/publications.html, e.g.
  80  * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and
  81  * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
  82  */
  83
  84 #include <stdio.h>
  85 #include "cryptlib.h"
  86 #include "bn_lcl.h"
  87
  88 #define MONT_WORD /* use the faster word-based algorithm */
  89
  90 int BN_mod_mul_montgomery(BIGNUM *r, BIGNUM *a, BIGNUM *b,
  91                           BN_MONT_CTX *mont, BN_CTX *ctx)
  92         {
  93         BIGNUM *tmp,*tmp2;
  94         int ret=0;
  95
  96         BN_CTX_start(ctx);
  97         tmp = BN_CTX_get(ctx);
  98         tmp2 = BN_CTX_get(ctx);
  99         if (tmp == NULL || tmp2 == NULL) goto err;
 100
 101         bn_check_top(tmp);
 102         bn_check_top(tmp2);
 103
 104         if (a == b)
 105                 {
 106 #if 0
 107                 bn_wexpand(tmp,a->top*2);
 108                 bn_wexpand(tmp2,a->top*4);
 109                 bn_sqr_recursive(tmp->d,a->d,a->top,tmp2->d);
 110                 tmp->top=a->top*2;
 111                 if (tmp->d[tmp->top-1] == 0)
 112                         tmp->top--;
 113 #else
 114                 if (!BN_sqr(tmp,a,ctx)) goto err;
 115 #endif
 116                 }
 117         else
 118                 {
 119                 if (!BN_mul(tmp,a,b,ctx)) goto err;
 120                 }
 121         /* reduce from aRR to aR */
 122         if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
 123         ret=1;
 124 err:
 125         BN_CTX_end(ctx);
 126         return(ret);
 127         }
 128
 129 int BN_from_montgomery(BIGNUM *ret, BIGNUM *a, BN_MONT_CTX *mont,
 130              BN_CTX *ctx)
 131         {
 132         int retn=0;
 133
 134 #ifdef MONT_WORD
 135         BIGNUM *n,*r;
 136         BN_ULONG *ap,*np,*rp,n0,v,*nrp;
 137         int al,nl,max,i,x,ri;
 138
 139         BN_CTX_start(ctx);
 140         if ((r = BN_CTX_get(ctx)) == NULL) goto err;
 141
 142         if (!BN_copy(r,a)) goto err;
 143         n= &(mont->N);
 144
 145         ap=a->d;
 146         /* mont->ri is the size of mont->N in bits (rounded up
 147            to the word size) */
 148         al=ri=mont->ri/BN_BITS2;
 149
 150         nl=n->top;
 151         if ((al == 0) || (nl == 0)) { r->top=0; return(1); }
 152
 153         max=(nl+al+1); /* allow for overflow (no?) XXX */
 154         if (bn_wexpand(r,max) == NULL) goto err;
 155         if (bn_wexpand(ret,max) == NULL) goto err;
 156
 157         r->neg=a->neg^n->neg;
 158         np=n->d;
 159         rp=r->d;
 160         nrp= &(r->d[nl]);
 161
 162         /* clear the top words of T */
 163 #if 1
 164         for (i=r->top; i<max; i++) /* memset? XXX */
 165                 r->d[i]=0;
 166 #else
 167         memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG));
 168 #endif
 169
 170         r->top=max;
 171         n0=mont->n0;
 172
 173 #ifdef BN_COUNT
 174         printf("word BN_from_montgomery %d * %d\n",nl,nl);
 175 #endif
 176         for (i=0; i<nl; i++)
 177                 {
 178                 v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
 179                 nrp++;
 180                 rp++;
 181                 if (((nrp[-1]+=v)&BN_MASK2) >= v)
 182                         continue;
 183                 else
 184                         {
 185                         if (((++nrp[0])&BN_MASK2) != 0) continue;
 186                         if (((++nrp[1])&BN_MASK2) != 0) continue;
 187                         for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
 188                         }
 189                 }
 190         bn_fix_top(r);
 191
 192         /* mont->ri will be a multiple of the word size */
 193 #if 0
 194         BN_rshift(ret,r,mont->ri);
 195 #else
 196         x=ri;
 197         rp=ret->d;
 198         ap= &(r->d[x]);
 199         if (r->top < x)
 200                 al=0;
 201         else
 202                 al=r->top-x;
 203         ret->top=al;
 204         al-=4;
 205         for (i=0; i<al; i+=4)
 206                 {
 207                 BN_ULONG t1,t2,t3,t4;
 208
 209                 t1=ap[i+0];
 210                 t2=ap[i+1];
 211                 t3=ap[i+2];
 212                 t4=ap[i+3];
 213                 rp[i+0]=t1;
 214                 rp[i+1]=t2;
 215                 rp[i+2]=t3;
 216                 rp[i+3]=t4;
 217                 }
 218         al+=4;
 219         for (; i<al; i++)
 220                 rp[i]=ap[i];
 221 #endif
 222 #else /* !MONT_WORD */
 223         BIGNUM *t1,*t2;
 224
 225         BN_CTX_start(ctx);
 226         t1 = BN_CTX_get(ctx);
 227         t2 = BN_CTX_get(ctx);
 228         if (t1 == NULL || t2 == NULL) goto err;
 229
 230         if (!BN_copy(t1,a)) goto err;
 231         BN_mask_bits(t1,mont->ri);
 232
 233         if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err;
 234         BN_mask_bits(t2,mont->ri);
 235
 236         if (!BN_mul(t1,t2,&mont->N,ctx)) goto err;
 237         if (!BN_add(t2,a,t1)) goto err;
 238         BN_rshift(ret,t2,mont->ri);
 239 #endif /* MONT_WORD */
 240
 241         if (BN_ucmp(ret, &(mont->N)) >= 0)
 242                 {
 243                 BN_usub(ret,ret,&(mont->N));
 244                 }
 245         retn=1;
 246  err:
 247         BN_CTX_end(ctx);
 248         return(retn);
 249         }
 250
 251 BN_MONT_CTX *BN_MONT_CTX_new(void)
 252         {
 253         BN_MONT_CTX *ret;
 254
 255         if ((ret=(BN_MONT_CTX *)Malloc(sizeof(BN_MONT_CTX))) == NULL)
 256                 return(NULL);
 257
 258         BN_MONT_CTX_init(ret);
 259         ret->flags=BN_FLG_MALLOCED;
 260         return(ret);
 261         }
 262
 263 void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
 264         {
 265         ctx->ri=0;
 266         BN_init(&(ctx->RR));
 267         BN_init(&(ctx->N));
 268         BN_init(&(ctx->Ni));
 269         ctx->flags=0;
 270         }
 271
 272 void BN_MONT_CTX_free(BN_MONT_CTX *mont)
 273         {
 274         if(mont == NULL)
 275             return;
 276
 277         BN_free(&(mont->RR));
 278         BN_free(&(mont->N));
 279         BN_free(&(mont->Ni));
 280         if (mont->flags & BN_FLG_MALLOCED)
 281                 Free(mont);
 282         }
 283
 284 int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
 285         {
 286         BIGNUM Ri,*R;
 287
 288         BN_init(&Ri);
 289         R= &(mont->RR);                                 /* grab RR as a temp */
 290         BN_copy(&(mont->N),mod);                        /* Set N */
 291
 292 #ifdef MONT_WORD
 293                 {
 294                 BIGNUM tmod;
 295                 BN_ULONG buf[2];
 296
 297                 mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
 298                 BN_zero(R);
 299                 BN_set_bit(R,BN_BITS2);                 /* R */
 300
 301                 buf[0]=mod->d[0]; /* tmod = N mod word size */
 302                 buf[1]=0;
 303                 tmod.d=buf;
 304                 tmod.top=1;
 305                 tmod.max=2;
 306                 tmod.neg=mod->neg;
 307                                                         /* Ri = R^-1 mod N*/
 308                 if ((BN_mod_inverse(&Ri,R,&tmod,ctx)) == NULL)
 309                         goto err;
 310                 BN_lshift(&Ri,&Ri,BN_BITS2);            /* R*Ri */
 311                 if (!BN_is_zero(&Ri))
 312                         BN_sub_word(&Ri,1);
 313                 else /* if N mod word size == 1 */
 314                         BN_set_word(&Ri,BN_MASK2);  /* Ri-- (mod word size) */
 315                 BN_div(&Ri,NULL,&Ri,&tmod,ctx); /* Ni = (R*Ri-1)/N,
 316                                                  * keep only least significant word: */
 317                 mont->n0=Ri.d[0];
 318                 BN_free(&Ri);
 319                 }
 320 #else /* !MONT_WORD */
 321                 { /* bignum version */
 322                 mont->ri=BN_num_bits(mod);
 323                 BN_zero(R);
 324                 BN_set_bit(R,mont->ri);                 /* R = 2^ri */
 325                                                         /* Ri = R^-1 mod N*/
 326                 if ((BN_mod_inverse(&Ri,R,mod,ctx)) == NULL)
 327                         goto err;
 328                 BN_lshift(&Ri,&Ri,mont->ri);            /* R*Ri */
 329                 BN_sub_word(&Ri,1);
 330                                                         /* Ni = (R*Ri-1) / N */
 331                 BN_div(&(mont->Ni),NULL,&Ri,mod,ctx);
 332                 BN_free(&Ri);
 333                 }
 334 #endif
 335
 336         /* setup RR for conversions */
 337         BN_zero(&(mont->RR));
 338         BN_set_bit(&(mont->RR),mont->ri*2);
 339         BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx);
 340
 341         return(1);
 342 err:
 343         return(0);
 344         }
 345
 346 BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from)
 347         {
 348         if (to == from) return(to);
 349
 350         BN_copy(&(to->RR),&(from->RR));
 351         BN_copy(&(to->N),&(from->N));
 352         BN_copy(&(to->Ni),&(from->Ni));
 353         to->ri=from->ri;
 354         to->n0=from->n0;
 355         return(to);
 356         }
 357