Donatien Garnier
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MiniTLS-GPL
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ltc_ecc_mulmod_timing.c
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00001 /* 00002 MiniTLS - A super trimmed down TLS/SSL Library for embedded devices 00003 Author: Donatien Garnier 00004 Copyright (C) 2013-2014 AppNearMe Ltd 00005 00006 This program is free software; you can redistribute it and/or 00007 modify it under the terms of the GNU General Public License 00008 as published by the Free Software Foundation; either version 2 00009 of the License, or (at your option) any later version. 00010 00011 This program is distributed in the hope that it will be useful, 00012 but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 GNU General Public License for more details. 00015 00016 You should have received a copy of the GNU General Public License 00017 along with this program; if not, write to the Free Software 00018 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. 00019 *//* LibTomCrypt, modular cryptographic library -- Tom St Denis 00020 * 00021 * LibTomCrypt is a library that provides various cryptographic 00022 * algorithms in a highly modular and flexible manner. 00023 * 00024 * The library is free for all purposes without any express 00025 * guarantee it works. 00026 * 00027 * Tom St Denis, tomstdenis@gmail.com, http://libtom.org 00028 */ 00029 00030 /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b 00031 * 00032 * All curves taken from NIST recommendation paper of July 1999 00033 * Available at http://csrc.nist.gov/cryptval/dss.htm 00034 */ 00035 #include "ltc.h" 00036 00037 /** 00038 @file ltc_ecc_mulmod_timing.c 00039 ECC Crypto, Tom St Denis 00040 */ 00041 00042 #ifdef LTC_MECC 00043 00044 #ifdef LTC_ECC_TIMING_RESISTANT 00045 00046 /** 00047 Perform a point multiplication (timing resistant) 00048 @param k The scalar to multiply by 00049 @param G The base point 00050 @param R [out] Destination for kG 00051 @param modulus The modulus of the field the ECC curve is in 00052 @param map Boolean whether to map back to affine or not (1==map, 0 == leave in projective) 00053 @return MINITLS_OK on success 00054 */ 00055 int ltc_ecc_mulmod(void *k, ecc_point *G, ecc_point *R, void *modulus, int map) 00056 { 00057 ecc_point tG, M[3]; 00058 int i, j, err; 00059 fp_int mu; 00060 fp_digit mp; 00061 unsigned long buf; 00062 int first, bitbuf, bitcpy, bitcnt, mode, digidx; 00063 00064 LTC_ARGCHK(k != NULL); 00065 LTC_ARGCHK(G != NULL); 00066 LTC_ARGCHK(R != NULL); 00067 LTC_ARGCHK(modulus != NULL); 00068 00069 /* init montgomery reduction */ 00070 if ((err = mp_montgomery_setup(modulus, &mp)) != MINITLS_OK) { 00071 return err; 00072 } 00073 /*if ((err =*/ mp_init(&mu);/*) != MINITLS_OK) { 00074 mp_montgomery_free(&mp); 00075 return err; 00076 }*/ 00077 /*if ((err =*/ mp_montgomery_normalization(&mu, modulus);/*) != MINITLS_OK) { 00078 mp_clear(&mu); 00079 mp_montgomery_free(&mp); 00080 return err; 00081 }*/ 00082 00083 /* alloc ram for window temps */ 00084 for (i = 0; i < 3; i++) { 00085 if (mp_init_multi(&M[i].x, &M[i].y, &M[i].z, NULL) != MINITLS_OK) 00086 { 00087 for (j = 0; j < i; j++) { 00088 mp_clear_multi(&M[j].x, &M[j].y, &M[j].z, NULL); 00089 } 00090 mp_clear(&mu); 00091 mp_montgomery_free(&mp); 00092 return MINITLS_ERR_MEMORY; 00093 } 00094 } 00095 00096 /* make a copy of G incase R==G */ 00097 if (mp_init_multi(&tG.x, &tG.y, &tG.z, NULL) != MINITLS_OK) { err = MINITLS_ERR_MEMORY; goto done; } 00098 00099 /* tG = G and convert to montgomery */ 00100 if ((err = mp_mulmod(&G->x, &mu, modulus, &tG.x)) != MINITLS_OK) { goto done; } 00101 if ((err = mp_mulmod(&G->y, &mu, modulus, &tG.y)) != MINITLS_OK) { goto done; } 00102 if ((err = mp_mulmod(&G->z, &mu, modulus, &tG.z)) != MINITLS_OK) { goto done; } 00103 mp_clear(&mu); 00104 //mu = NULL; 00105 00106 /* calc the M tab */ 00107 /* M[0] == G */ 00108 /*if ((err =*/ mp_copy(&tG.x, &M[0].x); /*) != MINITLS_OK) { goto done; }*/ 00109 /*if ((err =*/ mp_copy(&tG.y, &M[0].y); /*) != MINITLS_OK) { goto done; }*/ 00110 /*if ((err =*/ mp_copy(&tG.z, &M[0].z); /*) != MINITLS_OK) { goto done; }*/ 00111 /* M[1] == 2G */ 00112 if ((err = ltc_ecc_projective_dbl_point(&tG, &M[1], modulus, &mp)) != MINITLS_OK) { goto done; } 00113 00114 /* setup sliding window */ 00115 mode = 0; 00116 bitcnt = 1; 00117 buf = 0; 00118 digidx = mp_get_digit_count(k) - 1; 00119 bitcpy = bitbuf = 0; 00120 first = 1; 00121 00122 /* perform ops */ 00123 for (;;) { 00124 /* grab next digit as required */ 00125 if (--bitcnt == 0) { 00126 if (digidx == -1) { 00127 break; 00128 } 00129 buf = mp_get_digit(k, digidx); 00130 bitcnt = (int) MP_DIGIT_BIT; 00131 --digidx; 00132 } 00133 00134 /* grab the next msb from the ltiplicand */ 00135 i = (buf >> (MP_DIGIT_BIT - 1)) & 1; 00136 buf <<= 1; 00137 00138 if (mode == 0 && i == 0) { 00139 /* dummy operations */ 00140 if ((err = ltc_ecc_projective_add_point(&M[0], &M[1], &M[2], modulus, &mp)) != MINITLS_OK) { goto done; } 00141 if ((err = ltc_ecc_projective_dbl_point(&M[1], &M[2], modulus, &mp)) != MINITLS_OK) { goto done; } 00142 continue; 00143 } 00144 00145 if (mode == 0 && i == 1) { 00146 mode = 1; 00147 /* dummy operations */ 00148 if ((err = ltc_ecc_projective_add_point(&M[0], &M[1], &M[2], modulus, &mp)) != MINITLS_OK) { goto done; } 00149 if ((err = ltc_ecc_projective_dbl_point(&M[1], &M[2], modulus, &mp)) != MINITLS_OK) { goto done; } 00150 continue; 00151 } 00152 00153 if ((err = ltc_ecc_projective_add_point(&M[0], &M[1], &M[i^1], modulus, &mp)) != MINITLS_OK) { goto done; } 00154 if ((err = ltc_ecc_projective_dbl_point(&M[i], &M[i], modulus, &mp)) != MINITLS_OK) { goto done; } 00155 } 00156 00157 /* copy result out */ 00158 /*if ((err =*/ mp_copy(&M[0].x, &R->x);/*) != MINITLS_OK) { goto done; }*/ 00159 /*if ((err =*/ mp_copy(&M[0].y, &R->y);/*) != MINITLS_OK) { goto done; }*/ 00160 /*if ((err =*/ mp_copy(&M[0].z, &R->z);/*) != MINITLS_OK) { goto done; }*/ 00161 00162 /* map R back from projective space */ 00163 if (map) { 00164 err = ltc_ecc_map(R, modulus, &mp); 00165 } else { 00166 err = MINITLS_OK; 00167 } 00168 done: 00169 //if (mu != NULL) { 00170 mp_clear(&mu); 00171 //} 00172 mp_montgomery_free(&mp); 00173 mp_clear_multi(&tG.x, &tG.y, &tG.z, NULL); 00174 for (i = 0; i < 3; i++) { 00175 mp_clear_multi(&M[i].x, &M[i].y, &M[i].z, NULL); 00176 } 00177 return err; 00178 } 00179 00180 #endif 00181 #endif 00182 /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ltc_ecc_mulmod_timing.c,v $ */ 00183 /* $Revision: 1.13 $ */ 00184 /* $Date: 2007/05/12 14:32:35 $ */ 00185
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