155714Skris/* crypto/bn/bn_word.c */ 255714Skris/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 355714Skris * All rights reserved. 455714Skris * 555714Skris * This package is an SSL implementation written 655714Skris * by Eric Young (eay@cryptsoft.com). 755714Skris * The implementation was written so as to conform with Netscapes SSL. 8296341Sdelphij * 955714Skris * This library is free for commercial and non-commercial use as long as 1055714Skris * the following conditions are aheared to. The following conditions 1155714Skris * apply to all code found in this distribution, be it the RC4, RSA, 1255714Skris * lhash, DES, etc., code; not just the SSL code. The SSL documentation 1355714Skris * included with this distribution is covered by the same copyright terms 1455714Skris * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15296341Sdelphij * 1655714Skris * Copyright remains Eric Young's, and as such any Copyright notices in 1755714Skris * the code are not to be removed. 1855714Skris * If this package is used in a product, Eric Young should be given attribution 1955714Skris * as the author of the parts of the library used. 2055714Skris * This can be in the form of a textual message at program startup or 2155714Skris * in documentation (online or textual) provided with the package. 22296341Sdelphij * 2355714Skris * Redistribution and use in source and binary forms, with or without 2455714Skris * modification, are permitted provided that the following conditions 2555714Skris * are met: 2655714Skris * 1. Redistributions of source code must retain the copyright 2755714Skris * notice, this list of conditions and the following disclaimer. 2855714Skris * 2. Redistributions in binary form must reproduce the above copyright 2955714Skris * notice, this list of conditions and the following disclaimer in the 3055714Skris * documentation and/or other materials provided with the distribution. 3155714Skris * 3. All advertising materials mentioning features or use of this software 3255714Skris * must display the following acknowledgement: 3355714Skris * "This product includes cryptographic software written by 3455714Skris * Eric Young (eay@cryptsoft.com)" 3555714Skris * The word 'cryptographic' can be left out if the rouines from the library 3655714Skris * being used are not cryptographic related :-). 37296341Sdelphij * 4. If you include any Windows specific code (or a derivative thereof) from 3855714Skris * the apps directory (application code) you must include an acknowledgement: 3955714Skris * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40296341Sdelphij * 4155714Skris * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 4255714Skris * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 4355714Skris * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 4455714Skris * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 4555714Skris * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 4655714Skris * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 4755714Skris * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 4855714Skris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 4955714Skris * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 5055714Skris * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 5155714Skris * SUCH DAMAGE. 52296341Sdelphij * 5355714Skris * The licence and distribution terms for any publically available version or 5455714Skris * derivative of this code cannot be changed. i.e. this code cannot simply be 5555714Skris * copied and put under another distribution licence 5655714Skris * [including the GNU Public Licence.] 5755714Skris */ 5855714Skris 5955714Skris#include <stdio.h> 6055714Skris#include "cryptlib.h" 6155714Skris#include "bn_lcl.h" 6255714Skris 6359191SkrisBN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w) 64296341Sdelphij{ 6555714Skris#ifndef BN_LLONG 66296341Sdelphij BN_ULONG ret = 0; 6755714Skris#else 68296341Sdelphij BN_ULLONG ret = 0; 6955714Skris#endif 70296341Sdelphij int i; 7155714Skris 72296341Sdelphij if (w == 0) 73296341Sdelphij return (BN_ULONG)-1; 74160814Ssimon 75296341Sdelphij bn_check_top(a); 76296341Sdelphij w &= BN_MASK2; 77296341Sdelphij for (i = a->top - 1; i >= 0; i--) { 7855714Skris#ifndef BN_LLONG 79296341Sdelphij ret = ((ret << BN_BITS4) | ((a->d[i] >> BN_BITS4) & BN_MASK2l)) % w; 80296341Sdelphij ret = ((ret << BN_BITS4) | (a->d[i] & BN_MASK2l)) % w; 8155714Skris#else 82296341Sdelphij ret = (BN_ULLONG) (((ret << (BN_ULLONG) BN_BITS2) | a->d[i]) % 83296341Sdelphij (BN_ULLONG) w); 8455714Skris#endif 85296341Sdelphij } 86296341Sdelphij return ((BN_ULONG)ret); 87296341Sdelphij} 8855714Skris 8955714SkrisBN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w) 90296341Sdelphij{ 91296341Sdelphij BN_ULONG ret = 0; 92296341Sdelphij int i, j; 9355714Skris 94296341Sdelphij bn_check_top(a); 95296341Sdelphij w &= BN_MASK2; 96160814Ssimon 97296341Sdelphij if (!w) 98296341Sdelphij /* actually this an error (division by zero) */ 99296341Sdelphij return (BN_ULONG)-1; 100296341Sdelphij if (a->top == 0) 101296341Sdelphij return 0; 102160814Ssimon 103296341Sdelphij /* normalize input (so bn_div_words doesn't complain) */ 104296341Sdelphij j = BN_BITS2 - BN_num_bits_word(w); 105296341Sdelphij w <<= j; 106296341Sdelphij if (!BN_lshift(a, a, j)) 107296341Sdelphij return (BN_ULONG)-1; 108160814Ssimon 109296341Sdelphij for (i = a->top - 1; i >= 0; i--) { 110296341Sdelphij BN_ULONG l, d; 11155714Skris 112296341Sdelphij l = a->d[i]; 113296341Sdelphij d = bn_div_words(ret, l, w); 114296341Sdelphij ret = (l - ((d * w) & BN_MASK2)) & BN_MASK2; 115296341Sdelphij a->d[i] = d; 116296341Sdelphij } 117296341Sdelphij if ((a->top > 0) && (a->d[a->top - 1] == 0)) 118296341Sdelphij a->top--; 119296341Sdelphij ret >>= j; 120296341Sdelphij bn_check_top(a); 121296341Sdelphij return (ret); 122296341Sdelphij} 123296341Sdelphij 12455714Skrisint BN_add_word(BIGNUM *a, BN_ULONG w) 125296341Sdelphij{ 126296341Sdelphij BN_ULONG l; 127296341Sdelphij int i; 12855714Skris 129296341Sdelphij bn_check_top(a); 130296341Sdelphij w &= BN_MASK2; 131160814Ssimon 132296341Sdelphij /* degenerate case: w is zero */ 133296341Sdelphij if (!w) 134296341Sdelphij return 1; 135296341Sdelphij /* degenerate case: a is zero */ 136296341Sdelphij if (BN_is_zero(a)) 137296341Sdelphij return BN_set_word(a, w); 138296341Sdelphij /* handle 'a' when negative */ 139296341Sdelphij if (a->neg) { 140296341Sdelphij a->neg = 0; 141296341Sdelphij i = BN_sub_word(a, w); 142296341Sdelphij if (!BN_is_zero(a)) 143296341Sdelphij a->neg = !(a->neg); 144296341Sdelphij return (i); 145296341Sdelphij } 146296341Sdelphij for (i = 0; w != 0 && i < a->top; i++) { 147296341Sdelphij a->d[i] = l = (a->d[i] + w) & BN_MASK2; 148296341Sdelphij w = (w > l) ? 1 : 0; 149296341Sdelphij } 150296341Sdelphij if (w && i == a->top) { 151296341Sdelphij if (bn_wexpand(a, a->top + 1) == NULL) 152296341Sdelphij return 0; 153296341Sdelphij a->top++; 154296341Sdelphij a->d[i] = w; 155296341Sdelphij } 156296341Sdelphij bn_check_top(a); 157296341Sdelphij return (1); 158296341Sdelphij} 15955714Skris 16055714Skrisint BN_sub_word(BIGNUM *a, BN_ULONG w) 161296341Sdelphij{ 162296341Sdelphij int i; 16355714Skris 164296341Sdelphij bn_check_top(a); 165296341Sdelphij w &= BN_MASK2; 166160814Ssimon 167296341Sdelphij /* degenerate case: w is zero */ 168296341Sdelphij if (!w) 169296341Sdelphij return 1; 170296341Sdelphij /* degenerate case: a is zero */ 171296341Sdelphij if (BN_is_zero(a)) { 172296341Sdelphij i = BN_set_word(a, w); 173296341Sdelphij if (i != 0) 174296341Sdelphij BN_set_negative(a, 1); 175296341Sdelphij return i; 176296341Sdelphij } 177296341Sdelphij /* handle 'a' when negative */ 178296341Sdelphij if (a->neg) { 179296341Sdelphij a->neg = 0; 180296341Sdelphij i = BN_add_word(a, w); 181296341Sdelphij a->neg = 1; 182296341Sdelphij return (i); 183296341Sdelphij } 18455714Skris 185296341Sdelphij if ((a->top == 1) && (a->d[0] < w)) { 186296341Sdelphij a->d[0] = w - a->d[0]; 187296341Sdelphij a->neg = 1; 188296341Sdelphij return (1); 189296341Sdelphij } 190296341Sdelphij i = 0; 191296341Sdelphij for (;;) { 192296341Sdelphij if (a->d[i] >= w) { 193296341Sdelphij a->d[i] -= w; 194296341Sdelphij break; 195296341Sdelphij } else { 196296341Sdelphij a->d[i] = (a->d[i] - w) & BN_MASK2; 197296341Sdelphij i++; 198296341Sdelphij w = 1; 199296341Sdelphij } 200296341Sdelphij } 201296341Sdelphij if ((a->d[i] == 0) && (i == (a->top - 1))) 202296341Sdelphij a->top--; 203296341Sdelphij bn_check_top(a); 204296341Sdelphij return (1); 205296341Sdelphij} 20655714Skris 20755714Skrisint BN_mul_word(BIGNUM *a, BN_ULONG w) 208296341Sdelphij{ 209296341Sdelphij BN_ULONG ll; 21055714Skris 211296341Sdelphij bn_check_top(a); 212296341Sdelphij w &= BN_MASK2; 213296341Sdelphij if (a->top) { 214296341Sdelphij if (w == 0) 215296341Sdelphij BN_zero(a); 216296341Sdelphij else { 217296341Sdelphij ll = bn_mul_words(a->d, a->d, a->top, w); 218296341Sdelphij if (ll) { 219296341Sdelphij if (bn_wexpand(a, a->top + 1) == NULL) 220296341Sdelphij return (0); 221296341Sdelphij a->d[a->top++] = ll; 222296341Sdelphij } 223296341Sdelphij } 224296341Sdelphij } 225296341Sdelphij bn_check_top(a); 226296341Sdelphij return (1); 227296341Sdelphij} 228