3 This file is part of the AVR-Crypto-Lib.
4 Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
22 * email: daniel.otte@rub.de
23 * license: GPLv3 or later
30 #include <avr/pgmspace.h>
34 #define GRAIN_REVERSEKEY
36 /* s0, s1, s2, ..., s78, s79 */
37 #define S(i) ((ctx->lfsr[9-((i)/8)])>>(7-((i)%8)))
38 /* b0, b1, b2, ..., b78, b79 */
39 #define B(i) ((ctx->nfsr[9-((i)/8)])>>(7-((i)%8)))
40 #define _B(i) (((ctx->nfsr[9-((i)/8)])>>(7-((i)%8)))&1)
43 const uint8_t h_lut[4] PROGMEM = {0x4C, 0xB6, 0xD3, 0x26};
45 #ifdef GRAIN_BADOPTIMISATION
46 const uint8_t g_lut[128] PROGMEM = {
47 0xF0, 0xA5, 0x0F, 0x5A, 0x0F, 0x5A, 0xF0, 0xA5, 0x0F, 0x5A, 0xF0, 0xA5, 0xF0, 0x5A, 0x0F, 0x0F,
48 0xC3, 0x96, 0x3C, 0x69, 0x3C, 0x69, 0xC3, 0x96, 0x9C, 0xC9, 0x63, 0x36, 0x63, 0xC9, 0x9C, 0x9C,
49 0x0F, 0x5A, 0x0F, 0x5A, 0xF0, 0xA5, 0xF0, 0x5A, 0xF0, 0xA5, 0xF0, 0xA5, 0x0F, 0xA5, 0x0F, 0xF0,
50 0x3C, 0x69, 0x3C, 0x69, 0xC3, 0x96, 0xC3, 0x69, 0x63, 0x36, 0x63, 0x36, 0x9C, 0x36, 0x9C, 0x63,
51 0x0F, 0xD2, 0xF0, 0x2D, 0xF0, 0x2D, 0x0F, 0xD2, 0xF0, 0x2D, 0x0F, 0xD2, 0x0F, 0x2D, 0xF0, 0x78,
52 0x3C, 0xE1, 0xC3, 0x1E, 0xC3, 0x1E, 0x3C, 0xE1, 0x63, 0xBE, 0x9C, 0x41, 0x9C, 0xBE, 0x63, 0xEB,
53 0x00, 0xDD, 0x00, 0xDD, 0xFF, 0x22, 0xFF, 0xDD, 0xFF, 0x22, 0xFF, 0x22, 0x00, 0x22, 0xF0, 0x87,
54 0xF3, 0x2E, 0xF3, 0x2E, 0x0C, 0xD1, 0x0C, 0x2E, 0xAC, 0x71, 0xAC, 0x71, 0x53, 0x71, 0xA3, 0xD4 };
57 uint8_t grain_enc(grain_ctx_t *ctx){
58 uint8_t s80, s0, c1, c2;
62 s80 =S(62) ^ S(51) ^ S(38) ^ S(23) ^ S(13) ^ s0;
66 c2 = (ctx->lfsr[i])>>7;
67 ctx->lfsr[i] = ((ctx->lfsr[i])<<1) | c1;
72 /* 778 Byte in this variant / 617 clks enc_time */
73 #ifndef GRAIN_BADOPTIMISATION
75 b80 = B(62) ^ B(60) ^ B(52) ^ B(45) ^
76 B(37) ^ B(33) ^ B(28) ^ B(21) ^
77 B(14) ^ B( 9) ^ B( 0) ^ s0;
78 b80 ^= (a = B(63) & B(60));
79 b80 ^= (b = B(37) & B(33));
80 b80 ^= B(15) & B( 9); // c
81 b80 ^= (d = B(60) & B(52) & B(45));
82 b80 ^= (e = B(33) & B(28) & B(21));
83 b80 ^= B(63) & B(45) & B(28) & B(9); // f
85 b80 ^= b & B(60) & B(52); // g
86 b80 ^= a & B(21) & B(15); // h
87 b80 ^= d & B(63) & B(37); // i
88 b80 ^= e & B(15) & B( 9); // j
89 b80 ^= e & B(52) & B(45) & B(37); // k
91 /* let's reorder the bits */
106 x = ((ctx->nfsr[8])&0x41)<<1; // B15 & B09
107 x |= ((ctx->nfsr[2])&0x09); // B63 & B60
108 // x |= ((ctx->nfsr[4])&0x04)<<4; // B45
109 x |= (((ctx->nfsr[5])&0x44) |
110 ((ctx->nfsr[3])&0x08) |
111 (((((ctx->nfsr[7])&0x04)<<3) |((ctx->nfsr[4])&0x04))<<2) )<<2; // B37 & B33
112 // x |= ((ctx->nfsr[3])&0x08)<<2; // B52
113 x |= ((ctx->nfsr[6])&0x08)>>1; // B28
114 // x |= ((ctx->nfsr[7])&0x04)<<7; // B21
117 b80 = pgm_read_byte(g_lut+(x/8))>>(x%8);
118 b80 ^= s0 ^ B(62) ^ B(14) ^ B(0);
122 c2 = (ctx->nfsr[i])>>7;
123 ctx->nfsr[i] = ((ctx->nfsr[i])<<1) | c1;
126 /* now the h function */
134 h = (pgm_read_byte(h_lut+(i/8)))>>(i%8);
136 h ^= B(0) ^ B(1) ^ B(3) ^ B(9) ^ B(30) ^ B(42) ^ B(55);
140 uint8_t grain_getbyte(grain_ctx_t *ctx){
145 r |= grain_enc(ctx)?0x80:0x00;
150 #ifdef GRAIN_REVERSEKEY
153 uint8_t reverse_bits(uint8_t a){
155 0x0, 0x8, 0x4, 0xC, /* 0000 1000 0100 1100 */
156 0x2, 0xA, 0x6, 0xE, /* 0010 1010 0110 1110 */
157 0x1, 0x9, 0x5, 0xD, /* 0001 1001 0101 1101 */
158 0x3, 0xB, 0x7, 0xF }; /* 0011 1011 0111 1111 */
160 x = ((lut[a&0xf]) << 4) | lut[a>>4];
165 #define reverse_bits(a) (a)
169 void grain_init(const void *key, const void *iv, grain_ctx_t *ctx){
172 /* load the 80bit key */
174 ctx->nfsr[9-i] = reverse_bits(((uint8_t*)key)[i]);
176 /* load the 64bit iv */
178 ctx->lfsr[9-i] = reverse_bits(((uint8_t*)iv)[i]);
180 /* set the other bits of iv to 1 */
181 ctx->lfsr[0] = ctx->lfsr[1] = 0xFF;
183 /* run it 160 times */
184 for(i=0; i<160; ++i){