X-Git-Url: https://git.cryptolib.org/?a=blobdiff_plain;ds=sidebyside;f=a51%2FA5_1.c;fp=a51%2FA5_1.c;h=64b44f73ff865b381ab77bb62a39ec4b977fc40e;hb=cf610f6848d1a6aef4de849f9ec7895e20605583;hp=0000000000000000000000000000000000000000;hpb=54cfadc0fd16b6995f1e3bab2c5766fae89c4a6b;p=avr-crypto-lib.git
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 .
+*/
+/*
+ * 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
+#include
+#include "A5_1.h"
+#include
+
+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>i);
+ c->r1[0] ^= t;
+ c->r2[0] ^= t;
+ c->r3[0] ^= t;
+ a5_1_clock_core(c, 0x7);
+ }
+ for(i=0; i>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;
+}
+
+
+
+