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. 8280304Sjkim * 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). 15280304Sjkim * 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. 22280304Sjkim * 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 :-). 37280304Sjkim * 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)" 40280304Sjkim * 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. 52280304Sjkim * 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) 64280304Sjkim{ 6555714Skris#ifndef BN_LLONG 66280304Sjkim BN_ULONG ret = 0; 6755714Skris#else 68280304Sjkim BN_ULLONG ret = 0; 6955714Skris#endif 70280304Sjkim int i; 7155714Skris 72280304Sjkim if (w == 0) 73280304Sjkim return (BN_ULONG)-1; 74160814Ssimon 75280304Sjkim bn_check_top(a); 76280304Sjkim w &= BN_MASK2; 77280304Sjkim for (i = a->top - 1; i >= 0; i--) { 7855714Skris#ifndef BN_LLONG 79280304Sjkim ret = ((ret << BN_BITS4) | ((a->d[i] >> BN_BITS4) & BN_MASK2l)) % w; 80280304Sjkim ret = ((ret << BN_BITS4) | (a->d[i] & BN_MASK2l)) % w; 8155714Skris#else 82280304Sjkim ret = (BN_ULLONG) (((ret << (BN_ULLONG) BN_BITS2) | a->d[i]) % 83280304Sjkim (BN_ULLONG) w); 8455714Skris#endif 85280304Sjkim } 86280304Sjkim return ((BN_ULONG)ret); 87280304Sjkim} 8855714Skris 8955714SkrisBN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w) 90280304Sjkim{ 91280304Sjkim BN_ULONG ret = 0; 92280304Sjkim int i, j; 9355714Skris 94280304Sjkim bn_check_top(a); 95280304Sjkim w &= BN_MASK2; 96160814Ssimon 97280304Sjkim if (!w) 98280304Sjkim /* actually this an error (division by zero) */ 99280304Sjkim return (BN_ULONG)-1; 100280304Sjkim if (a->top == 0) 101280304Sjkim return 0; 102160814Ssimon 103280304Sjkim /* normalize input (so bn_div_words doesn't complain) */ 104280304Sjkim j = BN_BITS2 - BN_num_bits_word(w); 105280304Sjkim w <<= j; 106280304Sjkim if (!BN_lshift(a, a, j)) 107280304Sjkim return (BN_ULONG)-1; 108160814Ssimon 109280304Sjkim for (i = a->top - 1; i >= 0; i--) { 110280304Sjkim BN_ULONG l, d; 11155714Skris 112280304Sjkim l = a->d[i]; 113280304Sjkim d = bn_div_words(ret, l, w); 114280304Sjkim ret = (l - ((d * w) & BN_MASK2)) & BN_MASK2; 115280304Sjkim a->d[i] = d; 116280304Sjkim } 117280304Sjkim if ((a->top > 0) && (a->d[a->top - 1] == 0)) 118280304Sjkim a->top--; 119280304Sjkim ret >>= j; 120280304Sjkim bn_check_top(a); 121280304Sjkim return (ret); 122280304Sjkim} 123280304Sjkim 12455714Skrisint BN_add_word(BIGNUM *a, BN_ULONG w) 125280304Sjkim{ 126280304Sjkim BN_ULONG l; 127280304Sjkim int i; 12855714Skris 129280304Sjkim bn_check_top(a); 130280304Sjkim w &= BN_MASK2; 131160814Ssimon 132280304Sjkim /* degenerate case: w is zero */ 133280304Sjkim if (!w) 134280304Sjkim return 1; 135280304Sjkim /* degenerate case: a is zero */ 136280304Sjkim if (BN_is_zero(a)) 137280304Sjkim return BN_set_word(a, w); 138280304Sjkim /* handle 'a' when negative */ 139280304Sjkim if (a->neg) { 140280304Sjkim a->neg = 0; 141280304Sjkim i = BN_sub_word(a, w); 142280304Sjkim if (!BN_is_zero(a)) 143280304Sjkim a->neg = !(a->neg); 144280304Sjkim return (i); 145280304Sjkim } 146280304Sjkim for (i = 0; w != 0 && i < a->top; i++) { 147280304Sjkim a->d[i] = l = (a->d[i] + w) & BN_MASK2; 148280304Sjkim w = (w > l) ? 1 : 0; 149280304Sjkim } 150280304Sjkim if (w && i == a->top) { 151280304Sjkim if (bn_wexpand(a, a->top + 1) == NULL) 152280304Sjkim return 0; 153280304Sjkim a->top++; 154280304Sjkim a->d[i] = w; 155280304Sjkim } 156280304Sjkim bn_check_top(a); 157280304Sjkim return (1); 158280304Sjkim} 15955714Skris 16055714Skrisint BN_sub_word(BIGNUM *a, BN_ULONG w) 161280304Sjkim{ 162280304Sjkim int i; 16355714Skris 164280304Sjkim bn_check_top(a); 165280304Sjkim w &= BN_MASK2; 166160814Ssimon 167280304Sjkim /* degenerate case: w is zero */ 168280304Sjkim if (!w) 169280304Sjkim return 1; 170280304Sjkim /* degenerate case: a is zero */ 171280304Sjkim if (BN_is_zero(a)) { 172280304Sjkim i = BN_set_word(a, w); 173280304Sjkim if (i != 0) 174280304Sjkim BN_set_negative(a, 1); 175280304Sjkim return i; 176280304Sjkim } 177280304Sjkim /* handle 'a' when negative */ 178280304Sjkim if (a->neg) { 179280304Sjkim a->neg = 0; 180280304Sjkim i = BN_add_word(a, w); 181280304Sjkim a->neg = 1; 182280304Sjkim return (i); 183280304Sjkim } 18455714Skris 185280304Sjkim if ((a->top == 1) && (a->d[0] < w)) { 186280304Sjkim a->d[0] = w - a->d[0]; 187280304Sjkim a->neg = 1; 188280304Sjkim return (1); 189280304Sjkim } 190280304Sjkim i = 0; 191280304Sjkim for (;;) { 192280304Sjkim if (a->d[i] >= w) { 193280304Sjkim a->d[i] -= w; 194280304Sjkim break; 195280304Sjkim } else { 196280304Sjkim a->d[i] = (a->d[i] - w) & BN_MASK2; 197280304Sjkim i++; 198280304Sjkim w = 1; 199280304Sjkim } 200280304Sjkim } 201280304Sjkim if ((a->d[i] == 0) && (i == (a->top - 1))) 202280304Sjkim a->top--; 203280304Sjkim bn_check_top(a); 204280304Sjkim return (1); 205280304Sjkim} 20655714Skris 20755714Skrisint BN_mul_word(BIGNUM *a, BN_ULONG w) 208280304Sjkim{ 209280304Sjkim BN_ULONG ll; 21055714Skris 211280304Sjkim bn_check_top(a); 212280304Sjkim w &= BN_MASK2; 213280304Sjkim if (a->top) { 214280304Sjkim if (w == 0) 215280304Sjkim BN_zero(a); 216280304Sjkim else { 217280304Sjkim ll = bn_mul_words(a->d, a->d, a->top, w); 218280304Sjkim if (ll) { 219280304Sjkim if (bn_wexpand(a, a->top + 1) == NULL) 220280304Sjkim return (0); 221280304Sjkim a->d[a->top++] = ll; 222280304Sjkim } 223280304Sjkim } 224280304Sjkim } 225280304Sjkim bn_check_top(a); 226280304Sjkim return (1); 227280304Sjkim} 228