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@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 */
gcm_rightshift(unsigned char * a)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 */
gcm_gf_mult(const unsigned char * a,const unsigned char * b,unsigned char * c)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 */
gcm_gf_mult(const unsigned char * a,const unsigned char * b,unsigned char * c)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