--- /dev/null
+/* grain.c */
+/*
+ This file is part of the AVR-Crypto-Lib.
+ Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+/**
+ *
+ * author: Daniel Otte
+ * email: daniel.otte@rub.de
+ * license: GPLv3 or later
+ *
+ */
+
+
+#include <stdint.h>
+#include <string.h>
+#include <avr/pgmspace.h>
+#include "grain.h"
+
+
+#define GRAIN_REVERSEKEY
+
+/* s0, s1, s2, ..., s78, s79 */
+#define S(i) ((ctx->lfsr[9-((i)/8)])>>(7-((i)%8)))
+/* b0, b1, b2, ..., b78, b79 */
+#define B(i) ((ctx->nfsr[9-((i)/8)])>>(7-((i)%8)))
+#define _B(i) (((ctx->nfsr[9-((i)/8)])>>(7-((i)%8)))&1)
+
+
+uint8_t h_lut[4] PROGMEM = {0x4C, 0xB6, 0xD3, 0x26};
+
+#ifdef GRAIN_BADOPTIMISATION
+uint8_t g_lut[128] PROGMEM = {
+ 0xF0, 0xA5, 0x0F, 0x5A, 0x0F, 0x5A, 0xF0, 0xA5, 0x0F, 0x5A, 0xF0, 0xA5, 0xF0, 0x5A, 0x0F, 0x0F,
+ 0xC3, 0x96, 0x3C, 0x69, 0x3C, 0x69, 0xC3, 0x96, 0x9C, 0xC9, 0x63, 0x36, 0x63, 0xC9, 0x9C, 0x9C,
+ 0x0F, 0x5A, 0x0F, 0x5A, 0xF0, 0xA5, 0xF0, 0x5A, 0xF0, 0xA5, 0xF0, 0xA5, 0x0F, 0xA5, 0x0F, 0xF0,
+ 0x3C, 0x69, 0x3C, 0x69, 0xC3, 0x96, 0xC3, 0x69, 0x63, 0x36, 0x63, 0x36, 0x9C, 0x36, 0x9C, 0x63,
+ 0x0F, 0xD2, 0xF0, 0x2D, 0xF0, 0x2D, 0x0F, 0xD2, 0xF0, 0x2D, 0x0F, 0xD2, 0x0F, 0x2D, 0xF0, 0x78,
+ 0x3C, 0xE1, 0xC3, 0x1E, 0xC3, 0x1E, 0x3C, 0xE1, 0x63, 0xBE, 0x9C, 0x41, 0x9C, 0xBE, 0x63, 0xEB,
+ 0x00, 0xDD, 0x00, 0xDD, 0xFF, 0x22, 0xFF, 0xDD, 0xFF, 0x22, 0xFF, 0x22, 0x00, 0x22, 0xF0, 0x87,
+ 0xF3, 0x2E, 0xF3, 0x2E, 0x0C, 0xD1, 0x0C, 0x2E, 0xAC, 0x71, 0xAC, 0x71, 0x53, 0x71, 0xA3, 0xD4 };
+#endif
+
+uint8_t grain_enc(grain_ctx_t* ctx){
+ uint8_t s80, s0, c1, c2;
+ uint8_t i;
+ /* clock the LFSR */
+ s0=S(0);
+ s80 =S(62) ^ S(51) ^ S(38) ^ S(23) ^ S(13) ^ s0;
+ s80 &= 1;
+ c1 = s80;
+ for(i=0; i<10; ++i){
+ c2 = (ctx->lfsr[i])>>7;
+ ctx->lfsr[i] = ((ctx->lfsr[i])<<1) | c1;
+ c1 = c2;
+ }
+ /* clock the NFSR */
+ uint8_t b80;
+/* 778 Byte in this variant / 617 clks enc_time */
+#ifndef GRAIN_BADOPTIMISATION
+ uint8_t a,b,d,e;
+ b80 = B(62) ^ B(60) ^ B(52) ^ B(45) ^
+ B(37) ^ B(33) ^ B(28) ^ B(21) ^
+ B(14) ^ B( 9) ^ B( 0) ^ s0;
+ b80 ^= (a = B(63) & B(60));
+ b80 ^= (b = B(37) & B(33));
+ b80 ^= B(15) & B( 9); // c
+ b80 ^= (d = B(60) & B(52) & B(45));
+ b80 ^= (e = B(33) & B(28) & B(21));
+ b80 ^= B(63) & B(45) & B(28) & B(9); // f
+ /* -- */
+ b80 ^= b & B(60) & B(52); // g
+ b80 ^= a & B(21) & B(15); // h
+ b80 ^= d & B(63) & B(37); // i
+ b80 ^= e & B(15) & B( 9); // j
+ b80 ^= e & B(52) & B(45) & B(37); // k
+#else
+ /* let's reorder the bits */
+ uint16_t x;
+
+/*
+ x = _B(21); x<<=1;
+ x |= _B(33); x<<=1;
+ x |= _B(9) ; x<<=1;
+ x |= _B(45); x<<=1;
+ x |= _B(52); x<<=1;
+ x |= _B(37); x<<=1;
+ x |= _B(60); x<<=1;
+ x |= _B(28); x<<=1;
+ x |= _B(15); x<<=1;
+ x |= _B(63);
+*/
+ x = ((ctx->nfsr[8])&0x41)<<1; // B15 & B09
+ x |= ((ctx->nfsr[2])&0x09); // B63 & B60
+// x |= ((ctx->nfsr[4])&0x04)<<4; // B45
+ x |= (((ctx->nfsr[5])&0x44) |
+ ((ctx->nfsr[3])&0x08) |
+ (((((ctx->nfsr[7])&0x04)<<3) |((ctx->nfsr[4])&0x04))<<2) )<<2; // B37 & B33
+// x |= ((ctx->nfsr[3])&0x08)<<2; // B52
+ x |= ((ctx->nfsr[6])&0x08)>>1; // B28
+// x |= ((ctx->nfsr[7])&0x04)<<7; // B21
+
+
+ b80 = pgm_read_byte(g_lut+(x/8))>>(x%8);
+ b80 ^= s0 ^ B(62) ^ B(14) ^ B(0);
+#endif
+ c1 = b80 & 1;
+ for(i=0; i<10; ++i){
+ c2 = (ctx->nfsr[i])>>7;
+ ctx->nfsr[i] = ((ctx->nfsr[i])<<1) | c1;
+ c1 = c2;
+ }
+ /* now the h function */
+ uint8_t h;
+ i = (S(2)&1) |
+ ((S(24)&1) << 1) |
+ ((S(45)&1) << 2) |
+ ((S(63)&1) << 3) |
+ ((B(62)&1) << 4);
+
+ h = (pgm_read_byte(h_lut+(i/8)))>>(i%8);
+
+ h ^= B(0) ^ B(1) ^ B(3) ^ B(9) ^ B(30) ^ B(42) ^ B(55);
+ return h&1;
+}
+
+#ifdef GRAIN_REVERSEKEY
+
+static
+uint8_t reverse_bits(uint8_t a){
+ uint8_t lut[16] = {
+ 0x0, 0x8, 0x4, 0xC, /* 0000 1000 0100 1100 */
+ 0x2, 0xA, 0x6, 0xE, /* 0010 1010 0110 1110 */
+ 0x1, 0x9, 0x5, 0xD, /* 0001 1001 0101 1101 */
+ 0x3, 0xB, 0x7, 0xF }; /* 0011 1011 0111 1111 */
+ uint8_t x;
+ x = ((lut[a&0xf]) << 4) | lut[a>>4];
+ return x;
+}
+#else
+
+#define reverse_bits(a) (a)
+
+#endif
+
+void grain_init(const void* key, const void* iv, grain_ctx_t* ctx){
+ uint8_t i,t;
+
+ /* load the 80bit key */
+ for(i=0; i<10; ++i){
+ ctx->nfsr[9-i] = reverse_bits(((uint8_t*)key)[i]);
+ }
+ /* load the 64bit iv */
+ for(i=0; i<8; ++i){
+ ctx->lfsr[9-i] = reverse_bits(((uint8_t*)iv)[i]);
+ }
+ /* set the other bits of iv to 1 */
+ ctx->lfsr[0] = ctx->lfsr[1] = 0xFF;
+
+ /* run it 160 times */
+ for(i=0; i<160; ++i){
+ t = grain_enc(ctx);
+ (ctx->lfsr[0]) ^= t;
+ (ctx->nfsr[0]) ^= t;
+ }
+}
+
+
+
+
+
+
projects / avr-crypto-lib.git / blobdiff