1 /* ***** BEGIN LICENSE BLOCK ***** 2 * Version: MPL 1.1/GPL 2.0/LGPL 2.1 3 * 4 * The contents of this file are subject to the Mozilla Public License Version 5 * 1.1 (the "License"); you may not use this file except in compliance with 6 * the License. You may obtain a copy of the License at 7 * http://www.mozilla.org/MPL/ 8 * 9 * Software distributed under the License is distributed on an "AS IS" basis, 10 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License 11 * for the specific language governing rights and limitations under the 12 * License. 13 * 14 * The Original Code is the Netscape security libraries. 15 * 16 * The Initial Developer of the Original Code is 17 * Netscape Communications Corporation. 18 * Portions created by the Initial Developer are Copyright (C) 2000 19 * the Initial Developer. All Rights Reserved. 20 * 21 * Contributor(s): 22 * Sheueling Chang Shantz <sheueling.chang@sun.com>, 23 * Stephen Fung <stephen.fung@sun.com>, and 24 * Douglas Stebila <douglas@stebila.ca> of Sun Laboratories. 25 * 26 * Alternatively, the contents of this file may be used under the terms of 27 * either the GNU General Public License Version 2 or later (the "GPL"), or 28 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), 29 * in which case the provisions of the GPL or the LGPL are applicable instead 30 * of those above. If you wish to allow use of your version of this file only 31 * under the terms of either the GPL or the LGPL, and not to allow others to 32 * use your version of this file under the terms of the MPL, indicate your 33 * decision by deleting the provisions above and replace them with the notice 34 * and other provisions required by the GPL or the LGPL. If you do not delete 35 * the provisions above, a recipient may use your version of this file under 36 * the terms of any one of the MPL, the GPL or the LGPL. 37 * 38 * ***** END LICENSE BLOCK ***** */ 39 /* 40 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 41 * Use is subject to license terms. 42 * 43 * Copyright 2017 RackTop Systems. 44 * 45 * Sun elects to use this software under the MPL license. 46 */ 47 48 /* $Id: mpmontg.c,v 1.20 2006/08/29 02:41:38 nelson%bolyard.com Exp $ */ 49 50 /* This file implements moduluar exponentiation using Montgomery's 51 * method for modular reduction. This file implements the method 52 * described as "Improvement 1" in the paper "A Cryptogrpahic Library for 53 * the Motorola DSP56000" by Stephen R. Dusse' and Burton S. Kaliski Jr. 54 * published in "Advances in Cryptology: Proceedings of EUROCRYPT '90" 55 * "Lecture Notes in Computer Science" volume 473, 1991, pg 230-244, 56 * published by Springer Verlag. 57 */ 58 59 #define MP_USING_CACHE_SAFE_MOD_EXP 1 60 #ifndef _KERNEL 61 #include <string.h> 62 #include <stddef.h> /* ptrdiff_t */ 63 #endif 64 #include "mpi-priv.h" 65 #include "mplogic.h" 66 #include "mpprime.h" 67 #ifdef MP_USING_MONT_MULF 68 #include "montmulf.h" 69 #endif 70 71 /* if MP_CHAR_STORE_SLOW is defined, we */ 72 /* need to know endianness of this platform. */ 73 #ifdef MP_CHAR_STORE_SLOW 74 #if !defined(MP_IS_BIG_ENDIAN) && !defined(MP_IS_LITTLE_ENDIAN) 75 #error "You must define MP_IS_BIG_ENDIAN or MP_IS_LITTLE_ENDIAN\n" \ 76 " if you define MP_CHAR_STORE_SLOW." 77 #endif 78 #endif 79 80 #ifndef STATIC 81 #define STATIC 82 #endif 83 84 #define MAX_ODD_INTS 32 /* 2 ** (WINDOW_BITS - 1) */ 85 86 #ifndef _KERNEL 87 #if defined(_WIN32_WCE) 88 #define ABORT res = MP_UNDEF; goto CLEANUP 89 #else 90 #define ABORT abort() 91 #endif 92 #else 93 #define ABORT res = MP_UNDEF; goto CLEANUP 94 #endif /* _KERNEL */ 95 96 /* computes T = REDC(T), 2^b == R */ 97 mp_err s_mp_redc(mp_int *T, mp_mont_modulus *mmm) 98 { 99 mp_err res; 100 mp_size i; 101 102 i = MP_USED(T) + MP_USED(&mmm->N) + 2; 103 MP_CHECKOK( s_mp_pad(T, i) ); 104 for (i = 0; i < MP_USED(&mmm->N); ++i ) { 105 mp_digit m_i = MP_DIGIT(T, i) * mmm->n0prime; 106 /* T += N * m_i * (MP_RADIX ** i); */ 107 s_mp_mul_d_add_offset(&mmm->N, m_i, T, i); 108 } 109 s_mp_clamp(T); 110 111 /* T /= R */ 112 s_mp_div_2d(T, mmm->b); 113 114 if ((res = s_mp_cmp(T, &mmm->N)) >= 0) { 115 /* T = T - N */ 116 MP_CHECKOK( s_mp_sub(T, &mmm->N) ); 117 #ifdef DEBUG 118 if ((res = mp_cmp(T, &mmm->N)) >= 0) { 119 res = MP_UNDEF; 120 goto CLEANUP; 121 } 122 #endif 123 } 124 res = MP_OKAY; 125 CLEANUP: 126 return res; 127 } 128 129 #if !defined(MP_ASSEMBLY_MUL_MONT) && !defined(MP_MONT_USE_MP_MUL) 130 mp_err s_mp_mul_mont(const mp_int *a, const mp_int *b, mp_int *c, 131 mp_mont_modulus *mmm) 132 { 133 mp_digit *pb; 134 mp_digit m_i; 135 mp_err res; 136 mp_size ib; 137 mp_size useda, usedb; 138 139 ARGCHK(a != NULL && b != NULL && c != NULL, MP_BADARG); 140 141 if (MP_USED(a) < MP_USED(b)) { 142 const mp_int *xch = b; /* switch a and b, to do fewer outer loops */ 143 b = a; 144 a = xch; 145 } 146 147 MP_USED(c) = 1; MP_DIGIT(c, 0) = 0; 148 ib = MP_USED(a) + MP_MAX(MP_USED(b), MP_USED(&mmm->N)) + 2; 149 if((res = s_mp_pad(c, ib)) != MP_OKAY) 150 goto CLEANUP; 151 152 useda = MP_USED(a); 153 pb = MP_DIGITS(b); 154 s_mpv_mul_d(MP_DIGITS(a), useda, *pb++, MP_DIGITS(c)); 155 s_mp_setz(MP_DIGITS(c) + useda + 1, ib - (useda + 1)); 156 m_i = MP_DIGIT(c, 0) * mmm->n0prime; 157 s_mp_mul_d_add_offset(&mmm->N, m_i, c, 0); 158 159 /* Outer loop: Digits of b */ 160 usedb = MP_USED(b); 161 for (ib = 1; ib < usedb; ib++) { 162 mp_digit b_i = *pb++; 163 164 /* Inner product: Digits of a */ 165 if (b_i) 166 s_mpv_mul_d_add_prop(MP_DIGITS(a), useda, b_i, MP_DIGITS(c) + ib); 167 m_i = MP_DIGIT(c, ib) * mmm->n0prime; 168 s_mp_mul_d_add_offset(&mmm->N, m_i, c, ib); 169 } 170 if (usedb < MP_USED(&mmm->N)) { 171 for (usedb = MP_USED(&mmm->N); ib < usedb; ++ib ) { 172 m_i = MP_DIGIT(c, ib) * mmm->n0prime; 173 s_mp_mul_d_add_offset(&mmm->N, m_i, c, ib); 174 } 175 } 176 s_mp_clamp(c); 177 s_mp_div_2d(c, mmm->b); 178 if (s_mp_cmp(c, &mmm->N) >= 0) { 179 MP_CHECKOK( s_mp_sub(c, &mmm->N) ); 180 } 181 res = MP_OKAY; 182 183 CLEANUP: 184 return res; 185 } 186 #endif 187