1/* crypto/bn/bn_word.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#include <stdio.h> 60#include "cryptlib.h" 61#include "bn_lcl.h" 62 63BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w) 64 { 65#ifndef BN_LLONG 66 BN_ULONG ret=0; 67#else 68 BN_ULLONG ret=0; 69#endif 70 int i; 71 72 if (w == 0) 73 return (BN_ULONG)-1; 74 75 bn_check_top(a); 76 w&=BN_MASK2; 77 for (i=a->top-1; i>=0; i--) 78 { 79#ifndef BN_LLONG 80 ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%w; 81 ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%w; 82#else 83 ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])% 84 (BN_ULLONG)w); 85#endif 86 } 87 return((BN_ULONG)ret); 88 } 89 90BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w) 91 { 92 BN_ULONG ret = 0; 93 int i, j; 94 95 bn_check_top(a); 96 w &= BN_MASK2; 97 98 if (!w) 99 /* actually this an error (division by zero) */ 100 return (BN_ULONG)-1; 101 if (a->top == 0) 102 return 0; 103 104 /* normalize input (so bn_div_words doesn't complain) */ 105 j = BN_BITS2 - BN_num_bits_word(w); 106 w <<= j; 107 if (!BN_lshift(a, a, j)) 108 return (BN_ULONG)-1; 109 110 for (i=a->top-1; i>=0; i--) 111 { 112 BN_ULONG l,d; 113 114 l=a->d[i]; 115 d=bn_div_words(ret,l,w); 116 ret=(l-((d*w)&BN_MASK2))&BN_MASK2; 117 a->d[i]=d; 118 } 119 if ((a->top > 0) && (a->d[a->top-1] == 0)) 120 a->top--; 121 ret >>= j; 122 bn_check_top(a); 123 return(ret); 124 } 125 126int BN_add_word(BIGNUM *a, BN_ULONG w) 127 { 128 BN_ULONG l; 129 int i; 130 131 bn_check_top(a); 132 w &= BN_MASK2; 133 134 /* degenerate case: w is zero */ 135 if (!w) return 1; 136 /* degenerate case: a is zero */ 137 if(BN_is_zero(a)) return BN_set_word(a, w); 138 /* handle 'a' when negative */ 139 if (a->neg) 140 { 141 a->neg=0; 142 i=BN_sub_word(a,w); 143 if (!BN_is_zero(a)) 144 a->neg=!(a->neg); 145 return(i); 146 } 147 for (i=0;w!=0 && i<a->top;i++) 148 { 149 a->d[i] = l = (a->d[i]+w)&BN_MASK2; 150 w = (w>l)?1:0; 151 } 152 if (w && i==a->top) 153 { 154 if (bn_wexpand(a,a->top+1) == NULL) return 0; 155 a->top++; 156 a->d[i]=w; 157 } 158 bn_check_top(a); 159 return(1); 160 } 161 162int BN_sub_word(BIGNUM *a, BN_ULONG w) 163 { 164 int i; 165 166 bn_check_top(a); 167 w &= BN_MASK2; 168 169 /* degenerate case: w is zero */ 170 if (!w) return 1; 171 /* degenerate case: a is zero */ 172 if(BN_is_zero(a)) 173 { 174 i = BN_set_word(a,w); 175 if (i != 0) 176 BN_set_negative(a, 1); 177 return i; 178 } 179 /* handle 'a' when negative */ 180 if (a->neg) 181 { 182 a->neg=0; 183 i=BN_add_word(a,w); 184 a->neg=1; 185 return(i); 186 } 187 188 if ((a->top == 1) && (a->d[0] < w)) 189 { 190 a->d[0]=w-a->d[0]; 191 a->neg=1; 192 return(1); 193 } 194 i=0; 195 for (;;) 196 { 197 if (a->d[i] >= w) 198 { 199 a->d[i]-=w; 200 break; 201 } 202 else 203 { 204 a->d[i]=(a->d[i]-w)&BN_MASK2; 205 i++; 206 w=1; 207 } 208 } 209 if ((a->d[i] == 0) && (i == (a->top-1))) 210 a->top--; 211 bn_check_top(a); 212 return(1); 213 } 214 215int BN_mul_word(BIGNUM *a, BN_ULONG w) 216 { 217 BN_ULONG ll; 218 219 bn_check_top(a); 220 w&=BN_MASK2; 221 if (a->top) 222 { 223 if (w == 0) 224 BN_zero(a); 225 else 226 { 227 ll=bn_mul_words(a->d,a->d,a->top,w); 228 if (ll) 229 { 230 if (bn_wexpand(a,a->top+1) == NULL) return(0); 231 a->d[a->top++]=ll; 232 } 233 } 234 } 235 bn_check_top(a); 236 return(1); 237 } 238 239