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