X-Git-Url: https://git.cryptolib.org/?p=avr-crypto-lib.git;a=blobdiff_plain;f=a51%2FA5_1.c;fp=a51%2FA5_1.c;h=64b44f73ff865b381ab77bb62a39ec4b977fc40e;hp=0000000000000000000000000000000000000000;hb=cf610f6848d1a6aef4de849f9ec7895e20605583;hpb=54cfadc0fd16b6995f1e3bab2c5766fae89c4a6b

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;
+}
+
+
+
+