moving of A5/1

[avr-crypto-lib.git] / a51 / A5_1.c

diff --git a/a51/A5_1.c b/a51/A5_1.c
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+/* 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
+ * 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 bits!
+ */
+
+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);
+}
+
+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;
+} 
+
+const uint8_t parity3_lut[] PROGMEM = {0, 1, 1, 0,
+                                            1, 0, 0, 1};       
+const 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;
+       ret = a5_1_clock(c);
+       ret <<= 1;
+       ret = a5_1_clock(c);
+       ret <<= 1;
+       ret = a5_1_clock(c);
+       ret <<= 1;
+       ret = a5_1_clock(c);
+       ret <<= 1;
+       ret = a5_1_clock(c);
+       ret <<= 1;
+       ret = a5_1_clock(c);
+       ret <<= 1;
+       ret = a5_1_clock(c);
+       return ret;
+}
+
+
+
+