103 lines
2.5 KiB
C
103 lines
2.5 KiB
C
/* present.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2008 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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/**
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* present.c
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* a implementation of the PRESENT block-cipher
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* author: Daniel Otte
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* email: daniel.otte@rub.de
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* license: GPLv3
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*
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* */
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#include <string.h>
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#include <stdint.h>
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#include "present_speed.h"
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static
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void key_update(uint8_t* buffer, uint8_t round){
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uint8_t j;
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union __attribute__((packed)){
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uint8_t v8[2];
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uint16_t v16;
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} tmp;
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/* rotate buffer 19 right */
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tmp.v16 = ((uint16_t*)buffer)[4];
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j=4;
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do{
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((uint16_t*)buffer)[j] = ((uint16_t*)buffer)[j-1];
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}while(--j);
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((uint16_t*)buffer)[0] = tmp.v16;
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uint8_t t8;
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j=0;
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t8 = (uint16_t)buffer[9] << (5);
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do{
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tmp.v8[1] = buffer[j];
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tmp.v16 >>= 3;
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buffer[j] = tmp.v8[1] | t8;
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t8 = tmp.v8[0] & 0xe0;
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}while(++j<10);
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/* rotating done now substitution */
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buffer[0] = (present_sbox(buffer[0])&0xF0) | ((buffer[0])&0x0F);
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/* xor with round counter */
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buffer[8] ^= round << 7;
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buffer[7] ^= round >> 1;
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}
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void present_init(const uint8_t* key, uint8_t keysize_b, present_ctx_t* ctx){
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uint8_t i,key_buffer[10];
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memcpy(key_buffer, key, 10);
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memcpy(&(ctx->k[0]), key_buffer, 8);
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for(i=1; i<32; ++i){
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key_update(key_buffer, i);
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memcpy(&(ctx->k[i]), key_buffer, 8);
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}
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}
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void present_enc(void* buffer, present_ctx_t* ctx){
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uint8_t i,j,tmp[8];
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for(i=0; i<31; ++i){
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*((uint64_t*)buffer) ^= ctx->k[i];
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memxor(buffer, &ctx->k[i], 8);
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j = 7;
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do{
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tmp[j] = present_sbox(((uint8_t*)buffer)[j]);
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}while(j--);
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present_p(buffer, tmp);
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}
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memxor(buffer, &ctx->k[31], 8);
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}
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void present_dec(void* buffer, present_ctx_t* ctx){
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uint8_t j,tmp[8];
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uint8_t i;
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memxor(buffer, &ctx->k[31], 8);
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i = 30;
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do{
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present_p(tmp, buffer);
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present_p(buffer, tmp);
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j = 7;
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do{
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((uint8_t*)buffer)[j] = present_sbox_inv(((uint8_t*)buffer)[j]);
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}while(j--);
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memxor(buffer, &ctx->k[i], 8);
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}while(i--);
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}
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