+/* A5_1.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/>.
+*/
/*
- * File: A5_1.c
- * Author: Daniel Otte
- * Date: 24.06.2006
- * License: GPL
+ * File: A5_1.c
+ * Author: Daniel Otte
+ * email: daniel.otte@rub.de
+ * Date: 2006-06-24
+ * License: GPLv3 or later
* Description: Implementation of the A5/1 stream cipher algorithm, as used in GSM.
* ! Warning, this is weak crypto !
*
*/
#include <stdint.h>
+#include <string.h>
#include "A5_1.h"
+#include <avr/pgmspace.h>
+
+uint8_t a5_1_clock_core(a5_1_ctx_t *c, uint8_t clockoverride);
+
/*
- * length is length of key in bytes!
+ * length is length of key in bits!
*/
-#define BYTEn(p,s) (*(((uint8_t*)&(p))+s))
-
-void a5_1_init(a5_1_ctx_t *c, uint8_t *key, uint8_t length);
-
-bool a5_1_clock(a5_1_ctx_t *c){
- bool x1,x2,x3, maj;
- x1 = PARITY_LOOKUP & (1<< ((BYTEn(c->r1,2)+BYTEn(c->r1,1)>>5) & 0x7);
- x2 = PARITY_LOOKUP & (1<< (BYTEn(c->r2,2)>>4));
- x3 = PARITY_LLOKUP & (1<< ((BYTEn(c->r3,2)>>4+BYTEn(c->r3,0)>>7) & 0x7));
- maj = (((c->r1 & (1<<R1_CLK))?1:0)+((c->r2 & (1<<R2_CLK))?1:0)+((c->r3 & (1<<R3_CLK))?1:0))>=2;
- if (((c->r1 & (1<<R1_CLK))>>R1_CLK) == maj)
- c->r1 = c->r1<<1 + x1;
- if (((c->r2 & (1<<R2_CLK))>>R2_CLK) == maj)
- c->r2 = c->r2<<1 + x2;
- if (((c->r3 & (1<<R3_CLK))>>R3_CLK) == maj)
- c->r3 = c->r3<<1 + x3;
-
- return ((c->r1)>>(R1_LENGTH-1)+(c->r2)>>(R2_LENGTH-1)+(c->r3)>>(R3_LENGTH-1))&0x1;
+
+void a5_1_init(a5_1_ctx_t *c, void* key, uint8_t keylength_b, void* iv, uint8_t ivlength_b){
+ uint8_t i,t;
+ memset(c->r1, 0, 3);
+ memset(c->r2, 0, 3);
+ memset(c->r3, 0, 3);
+ for(i=0; i<keylength_b; ++i){
+ t=((uint8_t*)key)[i/8];
+ t=1&(t>>i);
+ c->r1[0] ^= t;
+ c->r2[0] ^= t;
+ c->r3[0] ^= t;
+ a5_1_clock_core(c, 0x7);
+ }
+ for(i=0; i<ivlength_b; ++i){
+ t=((uint8_t*)iv)[i/8];
+ t=1&(t>>i);
+ c->r1[0] ^= t;
+ c->r2[0] ^= t;
+ c->r3[0] ^= t;
+ a5_1_clock_core(c, 0x7);
+ }
+ for(i=0; i<100; ++i)
+ a5_1_clock_core(c,0);
}
-uint8_t a5_1_gen(a5_ 1_ctx_t *c){
+static
+void shiftreg(uint8_t* d){
+ uint8_t c, c2;
+ c=d[0]>>7;
+ d[0] <<= 1;
+ c2=d[1]>>7;
+ d[1] = (d[1]<<1) | c;
+ d[2] = (d[2]<<1) | c2;
+}
+
+ uint8_t parity3_lut[] PROGMEM = {0, 1, 1, 0,
+ 1, 0, 0, 1};
+ uint8_t clock_lut[] PROGMEM = {0x7, 0x6, 0x5, 0x3,
+ 0x3, 0x5, 0x6, 0x7};
+
+uint8_t a5_1_clock_core(a5_1_ctx_t *c, uint8_t clockoverride){
+ uint8_t ret,clk,fb;
+ ret = (0x04&c->r1[2]) | (0x20&c->r2[2]) | (0x40&c->r3[2]);
+ ret = ret^(ret>>6);
+ ret &= 0x7;
+ ret = pgm_read_byte(parity3_lut+ret);
+ clk = (0x08&c->r1[1]) | (0x10&c->r2[1]) | (0x20&c->r3[1]);
+ clk >>= 3;
+ clk = pgm_read_byte(clock_lut+clk);
+ clk |= clockoverride;
+
+ if(clk&1){
+ fb = c->r1[2] ^ (1&((c->r1[1])>>5));
+ fb &= 0x7;
+ fb = pgm_read_byte(parity3_lut+fb);
+ shiftreg(c->r1);
+ c->r1[0] |= fb;
+ c->r1[2] &= 0x07;
+ }
+ clk>>=1;
+ if(clk&1){
+ fb = c->r2[2]>>4 ;
+ fb &= 0x7;
+ fb = pgm_read_byte(parity3_lut+fb);
+ shiftreg(c->r2);
+ c->r2[0] |= fb;
+ c->r2[2] &= 0x3F;
+
+ }
+ clk>>=1;
+ if(clk&1){
+ fb = (c->r3[2]>>4) ^ (1&((c->r3[0])>>7));
+ fb &= 0x7;
+ fb = pgm_read_byte(parity3_lut+fb);
+ shiftreg(c->r3);
+ c->r3[0] |= fb;
+ c->r3[2] &= 0x7F;
+ }
+ return ret;
+}
+
+uint8_t a5_1_clock(a5_1_ctx_t *c){
+ return a5_1_clock_core(c, 0);
+}
+
+
+uint8_t a5_1_gen(a5_1_ctx_t *c){
uint8_t ret=0;
ret = a5_1_clock(c);
ret <<= 1;
projects / avr-crypto-lib.git / blobdiff