1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis 2 * 3 * LibTomCrypt is a library that provides various cryptographic 4 * algorithms in a highly modular and flexible manner. 5 * 6 * The library is free for all purposes without any express 7 * guarantee it works. 8 * 9 * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com 10 */ 11 12 /** 13 @file gcm_gf_mult.c 14 GCM implementation, do the GF mult, by Tom St Denis 15 */ 16 #include "tomcrypt.h" 17 18 #if defined(GCM_TABLES) || defined(LRW_TABLES) || ((defined(GCM_MODE) || defined(GCM_MODE)) && defined(LTC_FAST)) 19 20 /* this is x*2^128 mod p(x) ... the results are 16 bytes each stored in a packed format. Since only the 21 * lower 16 bits are not zero'ed I removed the upper 14 bytes */ 22 const unsigned char gcm_shift_table[256*2] = { 23 0x00, 0x00, 0x01, 0xc2, 0x03, 0x84, 0x02, 0x46, 0x07, 0x08, 0x06, 0xca, 0x04, 0x8c, 0x05, 0x4e, 24 0x0e, 0x10, 0x0f, 0xd2, 0x0d, 0x94, 0x0c, 0x56, 0x09, 0x18, 0x08, 0xda, 0x0a, 0x9c, 0x0b, 0x5e, 25 0x1c, 0x20, 0x1d, 0xe2, 0x1f, 0xa4, 0x1e, 0x66, 0x1b, 0x28, 0x1a, 0xea, 0x18, 0xac, 0x19, 0x6e, 26 0x12, 0x30, 0x13, 0xf2, 0x11, 0xb4, 0x10, 0x76, 0x15, 0x38, 0x14, 0xfa, 0x16, 0xbc, 0x17, 0x7e, 27 0x38, 0x40, 0x39, 0x82, 0x3b, 0xc4, 0x3a, 0x06, 0x3f, 0x48, 0x3e, 0x8a, 0x3c, 0xcc, 0x3d, 0x0e, 28 0x36, 0x50, 0x37, 0x92, 0x35, 0xd4, 0x34, 0x16, 0x31, 0x58, 0x30, 0x9a, 0x32, 0xdc, 0x33, 0x1e, 29 0x24, 0x60, 0x25, 0xa2, 0x27, 0xe4, 0x26, 0x26, 0x23, 0x68, 0x22, 0xaa, 0x20, 0xec, 0x21, 0x2e, 30 0x2a, 0x70, 0x2b, 0xb2, 0x29, 0xf4, 0x28, 0x36, 0x2d, 0x78, 0x2c, 0xba, 0x2e, 0xfc, 0x2f, 0x3e, 31 0x70, 0x80, 0x71, 0x42, 0x73, 0x04, 0x72, 0xc6, 0x77, 0x88, 0x76, 0x4a, 0x74, 0x0c, 0x75, 0xce, 32 0x7e, 0x90, 0x7f, 0x52, 0x7d, 0x14, 0x7c, 0xd6, 0x79, 0x98, 0x78, 0x5a, 0x7a, 0x1c, 0x7b, 0xde, 33 0x6c, 0xa0, 0x6d, 0x62, 0x6f, 0x24, 0x6e, 0xe6, 0x6b, 0xa8, 0x6a, 0x6a, 0x68, 0x2c, 0x69, 0xee, 34 0x62, 0xb0, 0x63, 0x72, 0x61, 0x34, 0x60, 0xf6, 0x65, 0xb8, 0x64, 0x7a, 0x66, 0x3c, 0x67, 0xfe, 35 0x48, 0xc0, 0x49, 0x02, 0x4b, 0x44, 0x4a, 0x86, 0x4f, 0xc8, 0x4e, 0x0a, 0x4c, 0x4c, 0x4d, 0x8e, 36 0x46, 0xd0, 0x47, 0x12, 0x45, 0x54, 0x44, 0x96, 0x41, 0xd8, 0x40, 0x1a, 0x42, 0x5c, 0x43, 0x9e, 37 0x54, 0xe0, 0x55, 0x22, 0x57, 0x64, 0x56, 0xa6, 0x53, 0xe8, 0x52, 0x2a, 0x50, 0x6c, 0x51, 0xae, 38 0x5a, 0xf0, 0x5b, 0x32, 0x59, 0x74, 0x58, 0xb6, 0x5d, 0xf8, 0x5c, 0x3a, 0x5e, 0x7c, 0x5f, 0xbe, 39 0xe1, 0x00, 0xe0, 0xc2, 0xe2, 0x84, 0xe3, 0x46, 0xe6, 0x08, 0xe7, 0xca, 0xe5, 0x8c, 0xe4, 0x4e, 40 0xef, 0x10, 0xee, 0xd2, 0xec, 0x94, 0xed, 0x56, 0xe8, 0x18, 0xe9, 0xda, 0xeb, 0x9c, 0xea, 0x5e, 41 0xfd, 0x20, 0xfc, 0xe2, 0xfe, 0xa4, 0xff, 0x66, 0xfa, 0x28, 0xfb, 0xea, 0xf9, 0xac, 0xf8, 0x6e, 42 0xf3, 0x30, 0xf2, 0xf2, 0xf0, 0xb4, 0xf1, 0x76, 0xf4, 0x38, 0xf5, 0xfa, 0xf7, 0xbc, 0xf6, 0x7e, 43 0xd9, 0x40, 0xd8, 0x82, 0xda, 0xc4, 0xdb, 0x06, 0xde, 0x48, 0xdf, 0x8a, 0xdd, 0xcc, 0xdc, 0x0e, 44 0xd7, 0x50, 0xd6, 0x92, 0xd4, 0xd4, 0xd5, 0x16, 0xd0, 0x58, 0xd1, 0x9a, 0xd3, 0xdc, 0xd2, 0x1e, 45 0xc5, 0x60, 0xc4, 0xa2, 0xc6, 0xe4, 0xc7, 0x26, 0xc2, 0x68, 0xc3, 0xaa, 0xc1, 0xec, 0xc0, 0x2e, 46 0xcb, 0x70, 0xca, 0xb2, 0xc8, 0xf4, 0xc9, 0x36, 0xcc, 0x78, 0xcd, 0xba, 0xcf, 0xfc, 0xce, 0x3e, 47 0x91, 0x80, 0x90, 0x42, 0x92, 0x04, 0x93, 0xc6, 0x96, 0x88, 0x97, 0x4a, 0x95, 0x0c, 0x94, 0xce, 48 0x9f, 0x90, 0x9e, 0x52, 0x9c, 0x14, 0x9d, 0xd6, 0x98, 0x98, 0x99, 0x5a, 0x9b, 0x1c, 0x9a, 0xde, 49 0x8d, 0xa0, 0x8c, 0x62, 0x8e, 0x24, 0x8f, 0xe6, 0x8a, 0xa8, 0x8b, 0x6a, 0x89, 0x2c, 0x88, 0xee, 50 0x83, 0xb0, 0x82, 0x72, 0x80, 0x34, 0x81, 0xf6, 0x84, 0xb8, 0x85, 0x7a, 0x87, 0x3c, 0x86, 0xfe, 51 0xa9, 0xc0, 0xa8, 0x02, 0xaa, 0x44, 0xab, 0x86, 0xae, 0xc8, 0xaf, 0x0a, 0xad, 0x4c, 0xac, 0x8e, 52 0xa7, 0xd0, 0xa6, 0x12, 0xa4, 0x54, 0xa5, 0x96, 0xa0, 0xd8, 0xa1, 0x1a, 0xa3, 0x5c, 0xa2, 0x9e, 53 0xb5, 0xe0, 0xb4, 0x22, 0xb6, 0x64, 0xb7, 0xa6, 0xb2, 0xe8, 0xb3, 0x2a, 0xb1, 0x6c, 0xb0, 0xae, 54 0xbb, 0xf0, 0xba, 0x32, 0xb8, 0x74, 0xb9, 0xb6, 0xbc, 0xf8, 0xbd, 0x3a, 0xbf, 0x7c, 0xbe, 0xbe }; 55 56 #endif 57 58 59 #if defined(GCM_MODE) || defined(LRW_MODE) 60 61 #ifndef LTC_FAST 62 /* right shift */ 63 static void gcm_rightshift(unsigned char *a) 64 { 65 int x; 66 for (x = 15; x > 0; x--) { 67 a[x] = (a[x]>>1) | ((a[x-1]<<7)&0x80); 68 } 69 a[0] >>= 1; 70 } 71 72 /* c = b*a */ 73 static const unsigned char mask[] = { 0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01 }; 74 static const unsigned char poly[] = { 0x00, 0xE1 }; 75 76 77 /** 78 GCM GF multiplier (internal use only) bitserial 79 @param a First value 80 @param b Second value 81 @param c Destination for a * b 82 */ 83 void gcm_gf_mult(const unsigned char *a, const unsigned char *b, unsigned char *c) 84 { 85 unsigned char Z[16], V[16]; 86 unsigned x, y, z; 87 88 zeromem(Z, 16); 89 XMEMCPY(V, a, 16); 90 for (x = 0; x < 128; x++) { 91 if (b[x>>3] & mask[x&7]) { 92 for (y = 0; y < 16; y++) { 93 Z[y] ^= V[y]; 94 } 95 } 96 z = V[15] & 0x01; 97 gcm_rightshift(V); 98 V[0] ^= poly[z]; 99 } 100 XMEMCPY(c, Z, 16); 101 } 102 103 #else 104 105 /* map normal numbers to "ieee" way ... e.g. bit reversed */ 106 #define M(x) ( ((x&8)>>3) | ((x&4)>>1) | ((x&2)<<1) | ((x&1)<<3) ) 107 108 #define BPD (sizeof(LTC_FAST_TYPE) * 8) 109 #define WPV (1 + (16 / sizeof(LTC_FAST_TYPE))) 110 111 /** 112 GCM GF multiplier (internal use only) word oriented 113 @param a First value 114 @param b Second value 115 @param c Destination for a * b 116 */ 117 void gcm_gf_mult(const unsigned char *a, const unsigned char *b, unsigned char *c) 118 { 119 int i, j, k, u; 120 LTC_FAST_TYPE B[16][WPV], tmp[32 / sizeof(LTC_FAST_TYPE)], pB[16 / sizeof(LTC_FAST_TYPE)], zz, z; 121 unsigned char pTmp[32]; 122 123 /* create simple tables */ 124 zeromem(B[0], sizeof(B[0])); 125 zeromem(B[M(1)], sizeof(B[M(1)])); 126 127 #ifdef ENDIAN_32BITWORD 128 for (i = 0; i < 4; i++) { 129 LOAD32H(B[M(1)][i], a + (i<<2)); 130 LOAD32L(pB[i], b + (i<<2)); 131 } 132 #else 133 for (i = 0; i < 2; i++) { 134 LOAD64H(B[M(1)][i], a + (i<<3)); 135 LOAD64L(pB[i], b + (i<<3)); 136 } 137 #endif 138 139 /* now create 2, 4 and 8 */ 140 B[M(2)][0] = B[M(1)][0] >> 1; 141 B[M(4)][0] = B[M(1)][0] >> 2; 142 B[M(8)][0] = B[M(1)][0] >> 3; 143 for (i = 1; i < (int)WPV; i++) { 144 B[M(2)][i] = (B[M(1)][i-1] << (BPD-1)) | (B[M(1)][i] >> 1); 145 B[M(4)][i] = (B[M(1)][i-1] << (BPD-2)) | (B[M(1)][i] >> 2); 146 B[M(8)][i] = (B[M(1)][i-1] << (BPD-3)) | (B[M(1)][i] >> 3); 147 } 148 149 /* now all values with two bits which are 3, 5, 6, 9, 10, 12 */ 150 for (i = 0; i < (int)WPV; i++) { 151 B[M(3)][i] = B[M(1)][i] ^ B[M(2)][i]; 152 B[M(5)][i] = B[M(1)][i] ^ B[M(4)][i]; 153 B[M(6)][i] = B[M(2)][i] ^ B[M(4)][i]; 154 B[M(9)][i] = B[M(1)][i] ^ B[M(8)][i]; 155 B[M(10)][i] = B[M(2)][i] ^ B[M(8)][i]; 156 B[M(12)][i] = B[M(8)][i] ^ B[M(4)][i]; 157 158 /* now all 3 bit values and the only 4 bit value: 7, 11, 13, 14, 15 */ 159 B[M(7)][i] = B[M(3)][i] ^ B[M(4)][i]; 160 B[M(11)][i] = B[M(3)][i] ^ B[M(8)][i]; 161 B[M(13)][i] = B[M(1)][i] ^ B[M(12)][i]; 162 B[M(14)][i] = B[M(6)][i] ^ B[M(8)][i]; 163 B[M(15)][i] = B[M(7)][i] ^ B[M(8)][i]; 164 } 165 166 zeromem(tmp, sizeof(tmp)); 167 168 /* compute product four bits of each word at a time */ 169 /* for each nibble */ 170 for (i = (BPD/4)-1; i >= 0; i--) { 171 /* for each word */ 172 for (j = 0; j < (int)(WPV-1); j++) { 173 /* grab the 4 bits recall the nibbles are backwards so it's a shift by (i^1)*4 */ 174 u = (pB[j] >> ((i^1)<<2)) & 15; 175 176 /* add offset by the word count the table looked up value to the result */ 177 for (k = 0; k < (int)WPV; k++) { 178 tmp[k+j] ^= B[u][k]; 179 } 180 } 181 /* shift result up by 4 bits */ 182 if (i != 0) { 183 for (z = j = 0; j < (int)(32 / sizeof(LTC_FAST_TYPE)); j++) { 184 zz = tmp[j] << (BPD-4); 185 tmp[j] = (tmp[j] >> 4) | z; 186 z = zz; 187 } 188 } 189 } 190 191 /* store product */ 192 #ifdef ENDIAN_32BITWORD 193 for (i = 0; i < 8; i++) { 194 STORE32H(tmp[i], pTmp + (i<<2)); 195 } 196 #else 197 for (i = 0; i < 4; i++) { 198 STORE64H(tmp[i], pTmp + (i<<3)); 199 } 200 #endif 201 202 /* reduce by taking most significant byte and adding the appropriate two byte sequence 16 bytes down */ 203 for (i = 31; i >= 16; i--) { 204 pTmp[i-16] ^= gcm_shift_table[((unsigned)pTmp[i]<<1)]; 205 pTmp[i-15] ^= gcm_shift_table[((unsigned)pTmp[i]<<1)+1]; 206 } 207 208 for (i = 0; i < 16; i++) { 209 c[i] = pTmp[i]; 210 } 211 212 } 213 214 #endif 215 216 #endif 217 218 /* $Source: /cvs/libtom/libtomcrypt/src/encauth/gcm/gcm_gf_mult.c,v $ */ 219 /* $Revision: 1.23 $ */ 220 /* $Date: 2006/03/31 14:15:35 $ */ 221 222
