cscrypt/bn_shift.c

   1 #include "bn.h"
   2
   3 #ifndef WITH_LIBCRYPTO
   4 //FIXME Not checked on threadsafety yet; after checking please remove this line
   5 /* crypto/bn/bn_shift.c */
   6 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   7  * All rights reserved.
   8  *
   9  * This package is an SSL implementation written
  10  * by Eric Young (eay@cryptsoft.com).
  11  * The implementation was written so as to conform with Netscapes SSL.
  12  *
  13  * This library is free for commercial and non-commercial use as long as
  14  * the following conditions are aheared to.  The following conditions
  15  * apply to all code found in this distribution, be it the RC4, RSA,
  16  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  17  * included with this distribution is covered by the same copyright terms
  18  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  19  *
  20  * Copyright remains Eric Young's, and as such any Copyright notices in
  21  * the code are not to be removed.
  22  * If this package is used in a product, Eric Young should be given attribution
  23  * as the author of the parts of the library used.
  24  * This can be in the form of a textual message at program startup or
  25  * in documentation (online or textual) provided with the package.
  26  *
  27  * Redistribution and use in source and binary forms, with or without
  28  * modification, are permitted provided that the following conditions
  29  * are met:
  30  * 1. Redistributions of source code must retain the copyright
  31  *    notice, this list of conditions and the following disclaimer.
  32  * 2. Redistributions in binary form must reproduce the above copyright
  33  *    notice, this list of conditions and the following disclaimer in the
  34  *    documentation and/or other materials provided with the distribution.
  35  * 3. All advertising materials mentioning features or use of this software
  36  *    must display the following acknowledgement:
  37  *    "This product includes cryptographic software written by
  38  *     Eric Young (eay@cryptsoft.com)"
  39  *    The word 'cryptographic' can be left out if the rouines from the library
  40  *    being used are not cryptographic related :-).
  41  * 4. If you include any Windows specific code (or a derivative thereof) from
  42  *    the apps directory (application code) you must include an acknowledgement:
  43  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  *
  57  * The license and distribution terms for any publically available version or
  58  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  59  * copied and put under another distribution license
  60  * [including the GNU Public License.]
  61  */
  62
  63 #include <stdio.h>
  64 #include <string.h>
  65 #include "bn_lcl.h"
  66 #include "openssl_mods.h"
  67
  68 int BN_lshift1(BIGNUM *r, BIGNUM *a)
  69 {
  70         register BN_ULONG *ap, *rp, t, c;
  71         int i;
  72
  73         if(r != a)
  74         {
  75                 r->neg = a->neg;
  76                 if(bn_wexpand(r, a->top + 1) == NULL) { return (0); }
  77                 r->top = a->top;
  78         }
  79         else
  80         {
  81                 if(bn_wexpand(r, a->top + 1) == NULL) { return (0); }
  82         }
  83         ap = a->d;
  84         rp = r->d;
  85         c = 0;
  86         for(i = 0; i < a->top; i++)
  87         {
  88                 t = *(ap++);
  89                 *(rp++) = ((t << 1) | c)&BN_MASK2;
  90                 c = (t & BN_TBIT) ? 1 : 0;
  91         }
  92         if(c)
  93         {
  94                 *rp = 1;
  95                 r->top++;
  96         }
  97         return (1);
  98 }
  99
 100 int BN_rshift1(BIGNUM *r, BIGNUM *a)
 101 {
 102         BN_ULONG *ap, *rp, t, c;
 103         int i;
 104
 105         if(BN_is_zero(a))
 106         {
 107                 BN_zero(r);
 108                 return (1);
 109         }
 110         if(a != r)
 111         {
 112                 if(bn_wexpand(r, a->top) == NULL) { return (0); }
 113                 r->top = a->top;
 114                 r->neg = a->neg;
 115         }
 116         ap = a->d;
 117         rp = r->d;
 118         c = 0;
 119         for(i = a->top - 1; i >= 0; i--)
 120         {
 121                 t = ap[i];
 122                 rp[i] = ((t >> 1)&BN_MASK2) | c;
 123                 c = (t & 1) ? BN_TBIT : 0;
 124         }
 125         bn_fix_top(r);
 126         return (1);
 127 }
 128
 129 int BN_lshift(BIGNUM *r, const BIGNUM *a, int n)
 130 {
 131         int i, nw, lb, rb;
 132         BN_ULONG *t, *f;
 133         BN_ULONG l;
 134
 135         r->neg = a->neg;
 136         if(bn_wexpand(r, a->top + (n / BN_BITS2) + 1) == NULL) { return (0); }
 137         nw = n / BN_BITS2;
 138         lb = n % BN_BITS2;
 139         rb = BN_BITS2 - lb;
 140         f = a->d;
 141         t = r->d;
 142         t[a->top + nw] = 0;
 143         if(lb == 0)
 144                 for(i = a->top - 1; i >= 0; i--)
 145                         { t[nw + i] = f[i]; }
 146         else
 147                 for(i = a->top - 1; i >= 0; i--)
 148                 {
 149                         l = f[i];
 150                         t[nw + i + 1] |= (l >> rb)&BN_MASK2;
 151                         t[nw + i] = (l << lb)&BN_MASK2;
 152                 }
 153         memset(t, 0, nw * sizeof(t[0]));
 154         /*  for (i=0; i<nw; i++)
 155                 t[i]=0;*/
 156         r->top = a->top + nw + 1;
 157         bn_fix_top(r);
 158         return (1);
 159 }
 160
 161 int BN_rshift(BIGNUM *r, BIGNUM *a, int n)
 162 {
 163         int i, j, nw, lb, rb;
 164         BN_ULONG *t, *f;
 165         BN_ULONG l, tmp;
 166
 167         nw = n / BN_BITS2;
 168         rb = n % BN_BITS2;
 169         lb = BN_BITS2 - rb;
 170         if(nw > a->top || a->top == 0)
 171         {
 172                 BN_zero(r);
 173                 return (1);
 174         }
 175         if(r != a)
 176         {
 177                 r->neg = a->neg;
 178                 if(bn_wexpand(r, a->top - nw + 1) == NULL) { return (0); }
 179         }
 180         else
 181         {
 182                 if(n == 0)
 183                         { return 1; } /* or the copying loop will go berserk */
 184         }
 185
 186         f = &(a->d[nw]);
 187         t = r->d;
 188         j = a->top - nw;
 189         r->top = j;
 190
 191         if(rb == 0)
 192         {
 193                 for(i = j + 1; i > 0; i--)
 194                         { *(t++) = *(f++); }
 195         }
 196         else
 197         {
 198                 l = *(f++);
 199                 for(i = 1; i < j; i++)
 200                 {
 201                         tmp = (l >> rb)&BN_MASK2;
 202                         l = *(f++);
 203                         *(t++) = (tmp | (l << lb))&BN_MASK2;
 204                 }
 205                 *(t++) = (l >> rb)&BN_MASK2;
 206         }
 207         *t = 0;
 208         bn_fix_top(r);
 209         return (1);
 210 }
 211 #endif