adding CS-Cipher

[avr-crypto-lib.git] / cscipher / cscipher_small.c

diff --git a/cscipher/cscipher_small.c b/cscipher/cscipher_small.c
new file mode 100644 (file)
index 0000000..9cec6e8
--- /dev/null
+++ b/cscipher/cscipher_small.c
@@ -0,0 +1,175 @@
+/* cscipher_small_core.c */
+/*
+    This file is part of the ARM-Crypto-Lib.
+    Copyright (C) 2006-2010 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/>.
+*/
+
+#include <stdint.h>
+#include <avr/pgmspace.h>
+#include <stdlib.h>
+#include <string.h>
+#include "memxor.h"
+#include "cscipher.h"
+
+#define DEBUG 0
+
+#if DEBUG
+#include "cli.h"
+#endif
+
+#define ROTL(a) (((a)<<1)|((a)>>7))
+
+#ifndef SBOX_PROG
+#define SBOX_PROG 0
+#endif
+
+#if SBOX_PROG
+static const uint8_t fg_table[] PROGMEM = {
+               0xfa, 0xd6, 0xb0, 0xb2, 0x7b, 0x5e, 0x71, 0x78,
+               0xed, 0xd4, 0xa5, 0xb3, 0xef, 0xdc, 0xe7, 0xf9
+};
+
+static
+uint8_t p(uint8_t a){
+       a ^= pgm_read_byte(fg_table+(a&0xf))&0xf0;
+       a ^= pgm_read_byte(fg_table+(a>>4)) &0x0f;
+       a ^= pgm_read_byte(fg_table+(a&0xf))&0xf0;
+       return a;
+}
+#define P(a) p(a)
+
+#else
+
+#include "cscipher_sbox.h"
+#define P(a) pgm_read_byte(cscipher_sbox+(a))
+#endif
+
+static uint8_t round_const[] PROGMEM = {
+       0xb7, 0xe1, 0x51, 0x62, 0x8a, 0xed, 0x2a, 0x6a,
+       0xbf, 0x71, 0x58, 0x80, 0x9c, 0xf4, 0xf3, 0xc7 };
+
+static uint8_t ks_const[] PROGMEM = {
+       0x29,0x0d,0x61,0x40,0x9c,0xeb,0x9e,0x8f,
+       0x1f,0x85,0x5f,0x58,0x5b,0x01,0x39,0x86,
+       0x97,0x2e,0xd7,0xd6,0x35,0xae,0x17,0x16,
+       0x21,0xb6,0x69,0x4e,0xa5,0x72,0x87,0x08,
+       0x3c,0x18,0xe6,0xe7,0xfa,0xad,0xb8,0x89,
+       0xb7,0x00,0xf7,0x6f,0x73,0x84,0x11,0x63,
+       0x3f,0x96,0x7f,0x6e,0xbf,0x14,0x9d,0xac,
+       0xa4,0x0e,0x7e,0xf6,0x20,0x4a,0x62,0x30,
+       0x03,0xc5,0x4b,0x5a,0x46,0xa3,0x44,0x65
+};
+
+static uint16_t m(uint16_t a){
+       uint8_t xl, xr, yl, yr;
+       uint16_t ret;
+       xr = a>>8;
+       xl = a&0xff;
+       yl = (ROTL(xl)&0x55)^xl^xr;
+       yr = ROTL(xl)^xr;
+       ret = (P(yr)<<8)|P(yl);
+       return ret;
+}
+
+static uint16_t m_inv(uint16_t a){
+       uint8_t xl, xr;
+       xr = P(a>>8);
+       xl = P(a&0xff);
+       xl ^= xr;
+       xl ^= (ROTL(xl)&0xaa);
+       xr ^= ROTL(xl);
+       return (xr<<8)|xl;
+}
+
+
+void cscipher_enc(void* buffer, const cscipher_ctx_t* ctx){
+       uint8_t i,j,k;
+       uint8_t tmp[8];
+       for(i=0; i<8; ++i){
+#if DEBUG
+               cli_putstr_P(PSTR("\r\nDBG: round "));
+               cli_hexdump(&i, 1);
+               cli_putstr_P(PSTR(" buffer:"));
+               cli_hexdump(buffer, 8);
+#endif
+               for(j=0; j<3; ++j){
+                       if(j==0){
+                               memxor(buffer, ctx->keys[i], 8);
+                       }else{
+                               memxor_P(buffer, round_const+((j==1)?0:8), 8);
+                       }
+                       for(k=0; k<4; ++k){
+                               ((uint16_t*)tmp)[k] = m(((uint16_t*)buffer)[k]);
+                       }
+                       for(k=0; k<4; ++k){
+                               ((uint8_t*)buffer)[k]   = tmp[2*k];
+                               ((uint8_t*)buffer)[k+4] = tmp[2*k+1];
+                       }
+               }
+       }
+       memxor(buffer, ctx->keys[8], 8);
+}
+
+void cscipher_dec(void* buffer, const cscipher_ctx_t* ctx){
+       uint8_t i=7,j,k;
+       uint8_t tmp[8];
+       memxor(buffer, ctx->keys[8], 8);
+       do{
+               for(j=0; j<3; ++j){
+                       for(k=0; k<4; ++k){
+                               tmp[2*k]   = ((uint8_t*)buffer)[k];
+                               tmp[2*k+1] = ((uint8_t*)buffer)[4+k];
+                       }
+                       for(k=0; k<4; ++k){
+                               ((uint16_t*)buffer)[k] = m_inv(((uint16_t*)tmp)[k]);
+                       }
+                       if(j==2){
+                               memxor(buffer, ctx->keys[i], 8);
+                       }else{
+                               memxor_P(buffer, round_const+((j==1)?0:8), 8);
+                       }
+
+               }
+       }while(i--);
+}
+
+void cscipher_init(void* key, cscipher_ctx_t* ctx){
+       uint8_t tmp_key[16], tmp[8];
+       uint8_t i,j,k,t;
+       memcpy(tmp_key, key, 16);
+       for(i=0; i<9; ++i){
+#if DEBUG
+               cli_putstr_P(PSTR("\r\nDBG: round "));
+               cli_hexdump(&i, 1);
+               cli_putstr_P(PSTR(" key state:"));
+               cli_hexdump(tmp_key, 16);
+#endif
+               memcpy(tmp, tmp_key+(((i&1)==0)?0:8), 8);
+               memxor_P(tmp, ks_const+8*i, 8);
+               for(j=0; j<8; ++j){
+                       tmp[j] = P(tmp[j]);
+               }
+               for(j=0; j<8; ++j){
+                       for(k=0; k<8; ++k){
+                               t<<=1;
+                               t |= tmp[k]>>7;
+                               tmp[k]<<=1;
+                       }
+                       tmp_key[j+(((i&1)==0)?8:0)] ^= t;
+               }
+               memcpy(ctx->keys[i], tmp_key+(((i&1)==0)?8:0), 8);
+       }
+}