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