AppleCSP/open_ssl/bn/bn_recp.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_recp.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 #include <stdio.h>
  78 #include "cryptlib.h"
  79 #include "bn_lcl.h"
  80
  81 void BN_RECP_CTX_init(BN_RECP_CTX *recp)
  82         {
  83         BN_init(&(recp->N));
  84         BN_init(&(recp->Nr));
  85         recp->num_bits=0;
  86         recp->flags=0;
  87         }
  88
  89 BN_RECP_CTX *BN_RECP_CTX_new(void)
  90         {
  91         BN_RECP_CTX *ret;
  92
  93         if ((ret=(BN_RECP_CTX *)Malloc(sizeof(BN_RECP_CTX))) == NULL)
  94                 return(NULL);
  95
  96         BN_RECP_CTX_init(ret);
  97         ret->flags=BN_FLG_MALLOCED;
  98         return(ret);
  99         }
 100
 101 void BN_RECP_CTX_free(BN_RECP_CTX *recp)
 102         {
 103         if(recp == NULL)
 104             return;
 105
 106         BN_free(&(recp->N));
 107         BN_free(&(recp->Nr));
 108         if (recp->flags & BN_FLG_MALLOCED)
 109                 Free(recp);
 110         }
 111
 112 int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
 113         {
 114         BN_copy(&(recp->N),d);
 115         BN_zero(&(recp->Nr));
 116         recp->num_bits=BN_num_bits(d);
 117         recp->shift=0;
 118         return(1);
 119         }
 120
 121 int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp,
 122              BN_CTX *ctx)
 123         {
 124         int ret=0;
 125         BIGNUM *a;
 126
 127         BN_CTX_start(ctx);
 128         if ((a = BN_CTX_get(ctx)) == NULL) goto err;
 129         if (y != NULL)
 130                 {
 131                 if (x == y)
 132                         { if (!BN_sqr(a,x,ctx)) goto err; }
 133                 else
 134                         { if (!BN_mul(a,x,y,ctx)) goto err; }
 135                 }
 136         else
 137                 a=x; /* Just do the mod */
 138
 139         BN_div_recp(NULL,r,a,recp,ctx);
 140         ret=1;
 141 err:
 142         BN_CTX_end(ctx);
 143         return(ret);
 144         }
 145
 146 int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
 147              BN_CTX *ctx)
 148         {
 149         int i,j,ret=0;
 150         BIGNUM *a,*b,*d,*r;
 151
 152         BN_CTX_start(ctx);
 153         a=BN_CTX_get(ctx);
 154         b=BN_CTX_get(ctx);
 155         if (dv != NULL)
 156                 d=dv;
 157         else
 158                 d=BN_CTX_get(ctx);
 159         if (rem != NULL)
 160                 r=rem;
 161         else
 162                 r=BN_CTX_get(ctx);
 163         if (a == NULL || b == NULL || d == NULL || r == NULL) goto err;
 164
 165         if (BN_ucmp(m,&(recp->N)) < 0)
 166                 {
 167                 BN_zero(d);
 168                 BN_copy(r,m);
 169                 BN_CTX_end(ctx);
 170                 return(1);
 171                 }
 172
 173         /* We want the remainder
 174          * Given input of ABCDEF / ab
 175          * we need multiply ABCDEF by 3 digests of the reciprocal of ab
 176          *
 177          */
 178         i=BN_num_bits(m);
 179
 180         j=recp->num_bits<<1;
 181         if (j>i) i=j;
 182         j>>=1;
 183
 184         if (i != recp->shift)
 185                 recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
 186                         i,ctx);
 187
 188         if (!BN_rshift(a,m,j)) goto err;
 189         if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
 190         if (!BN_rshift(d,b,i-j)) goto err;
 191         d->neg=0;
 192         if (!BN_mul(b,&(recp->N),d,ctx)) goto err;
 193         if (!BN_usub(r,m,b)) goto err;
 194         r->neg=0;
 195
 196 #if 1
 197         j=0;
 198         while (BN_ucmp(r,&(recp->N)) >= 0)
 199                 {
 200                 if (j++ > 2)
 201                         {
 202                         BNerr(BN_F_BN_MOD_MUL_RECIPROCAL,BN_R_BAD_RECIPROCAL);
 203                         goto err;
 204                         }
 205                 if (!BN_usub(r,r,&(recp->N))) goto err;
 206                 if (!BN_add_word(d,1)) goto err;
 207                 }
 208 #endif
 209
 210         r->neg=BN_is_zero(r)?0:m->neg;
 211         d->neg=m->neg^recp->N.neg;
 212         ret=1;
 213 err:
 214         BN_CTX_end(ctx);
 215         return(ret);
 216         }
 217
 218 /* len is the expected size of the result
 219  * We actually calculate with an extra word of precision, so
 220  * we can do faster division if the remainder is not required.
 221  */
 222 int BN_reciprocal(BIGNUM *r, BIGNUM *m, int len, BN_CTX *ctx)
 223         {
 224         int ret= -1;
 225         BIGNUM t;
 226
 227         BN_init(&t);
 228
 229         BN_zero(&t);
 230         if (!BN_set_bit(&t,len)) goto err;
 231
 232         if (!BN_div(r,NULL,&t,m,ctx)) goto err;
 233         ret=len;
 234 err:
 235         BN_free(&t);
 236         return(ret);
 237         }
 238