175 lines
3.9 KiB
C
175 lines
3.9 KiB
C
/* cscipher_small_core.c */
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/*
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This file is part of the ARM-Crypto-Lib.
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Copyright (C) 2006-2010 Daniel Otte (daniel.otte@rub.de)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include "memxor.h"
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#include "cscipher.h"
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#define DEBUG 0
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#if DEBUG
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#include "cli.h"
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#endif
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#define ROTL(a) (((a)<<1)|((a)>>7))
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#ifndef SBOX_PROG
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#define SBOX_PROG 0
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#endif
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#if SBOX_PROG
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static const uint8_t fg_table[] = {
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0xfa, 0xd6, 0xb0, 0xb2, 0x7b, 0x5e, 0x71, 0x78,
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0xed, 0xd4, 0xa5, 0xb3, 0xef, 0xdc, 0xe7, 0xf9
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};
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static
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uint8_t p(uint8_t a){
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a ^= fg_table[a&0xf]&0xf0;
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a ^= fg_table[a>>4] &0x0f;
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a ^= fg_table[a&0xf]&0xf0;
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return a;
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}
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#define P(a) p(a)
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#else
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#include "cscipher_sbox.h"
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#define P(a) (cscipher_sbox[(a)])
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#endif
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static const uint8_t round_const[] = {
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0xb7, 0xe1, 0x51, 0x62, 0x8a, 0xed, 0x2a, 0x6a,
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0xbf, 0x71, 0x58, 0x80, 0x9c, 0xf4, 0xf3, 0xc7 };
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static const uint8_t ks_const[] = {
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0x29,0x0d,0x61,0x40,0x9c,0xeb,0x9e,0x8f,
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0x1f,0x85,0x5f,0x58,0x5b,0x01,0x39,0x86,
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0x97,0x2e,0xd7,0xd6,0x35,0xae,0x17,0x16,
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0x21,0xb6,0x69,0x4e,0xa5,0x72,0x87,0x08,
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0x3c,0x18,0xe6,0xe7,0xfa,0xad,0xb8,0x89,
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0xb7,0x00,0xf7,0x6f,0x73,0x84,0x11,0x63,
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0x3f,0x96,0x7f,0x6e,0xbf,0x14,0x9d,0xac,
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0xa4,0x0e,0x7e,0xf6,0x20,0x4a,0x62,0x30,
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0x03,0xc5,0x4b,0x5a,0x46,0xa3,0x44,0x65
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};
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static uint16_t m(uint16_t a){
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uint8_t xl, xr, yl, yr;
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uint16_t ret;
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xr = a>>8;
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xl = a&0xff;
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yl = (ROTL(xl)&0x55)^xl^xr;
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yr = ROTL(xl)^xr;
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ret = (P(yr)<<8)|P(yl);
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return ret;
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}
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static uint16_t m_inv(uint16_t a){
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uint8_t xl, xr;
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xr = P(a>>8);
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xl = P(a&0xff);
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xl ^= xr;
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xl ^= (ROTL(xl)&0xaa);
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xr ^= ROTL(xl);
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return (xr<<8)|xl;
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}
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void cscipher_enc(void* buffer, const cscipher_ctx_t* ctx){
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uint8_t i,j,k;
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uint8_t tmp[8];
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for(i=0; i<8; ++i){
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#if DEBUG
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cli_putstr("\r\nDBG: round ");
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cli_hexdump(&i, 1);
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cli_putstr(" buffer:");
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cli_hexdump(buffer, 8);
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#endif
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for(j=0; j<3; ++j){
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if(j==0){
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memxor(buffer, ctx->keys[i], 8);
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}else{
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memxor(buffer, round_const+((j==1)?0:8), 8);
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}
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for(k=0; k<4; ++k){
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((uint16_t*)tmp)[k] = m(((uint16_t*)buffer)[k]);
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}
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for(k=0; k<4; ++k){
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((uint8_t*)buffer)[k] = tmp[2*k];
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((uint8_t*)buffer)[k+4] = tmp[2*k+1];
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}
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}
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}
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memxor(buffer, ctx->keys[8], 8);
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}
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void cscipher_dec(void* buffer, const cscipher_ctx_t* ctx){
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uint8_t i=7,j,k;
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uint8_t tmp[8];
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memxor(buffer, ctx->keys[8], 8);
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do{
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for(j=0; j<3; ++j){
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for(k=0; k<4; ++k){
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tmp[2*k] = ((uint8_t*)buffer)[k];
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tmp[2*k+1] = ((uint8_t*)buffer)[4+k];
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}
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for(k=0; k<4; ++k){
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((uint16_t*)buffer)[k] = m_inv(((uint16_t*)tmp)[k]);
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}
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if(j==2){
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memxor(buffer, ctx->keys[i], 8);
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}else{
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memxor(buffer, round_const+((j==1)?0:8), 8);
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}
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}
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}while(i--);
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}
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void cscipher_init(const void* key, cscipher_ctx_t* ctx){
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uint8_t tmp_key[16], tmp[8];
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uint8_t i,j,k,t=0;
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memcpy(tmp_key, key, 16);
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for(i=0; i<9; ++i){
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#if DEBUG
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cli_putstr("\r\nDBG: round ");
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cli_hexdump(&i, 1);
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cli_putstr(" key state:");
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cli_hexdump(tmp_key, 16);
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#endif
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memcpy(tmp, tmp_key+(((i&1)==0)?0:8), 8);
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memxor(tmp, ks_const+8*i, 8);
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for(j=0; j<8; ++j){
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tmp[j] = P(tmp[j]);
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}
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for(j=0; j<8; ++j){
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for(k=0; k<8; ++k){
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t<<=1;
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t |= tmp[k]>>7;
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tmp[k]<<=1;
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}
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tmp_key[j+(((i&1)==0)?8:0)] ^= t;
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}
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memcpy(ctx->keys[i], tmp_key+(((i&1)==0)?8:0), 8);
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}
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}
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