X-Git-Url: https://git.cryptolib.org/?a=blobdiff_plain;f=present%2Fpresent.c;fp=present%2Fpresent.c;h=6de3a6da4e3588f7f10ae025c78a811b48704809;hb=f4853b26a54089e6796fcf115f739f1e9ea7ceb7;hp=0000000000000000000000000000000000000000;hpb=083a6aff753ef04626cea2bdf1107ff24e93142c;p=arm-crypto-lib.git

diff --git a/present/present.c b/present/present.c
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+++ b/present/present.c
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+/* present.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/>.
+*/
+/**
+ * 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 "present.h"
+
+static uint8_t sbox(uint8_t b){
+	uint8_t sb[]={0xC, 0x5, 0x6, 0xB, 
+		 		  0x9, 0x0, 0xA, 0xD, 
+				  0x3, 0xE, 0xF, 0x8, 
+				  0x4, 0x7, 0x1, 0x2 };
+	return (((sb[b>>4])<<4)|(sb[b&0xf]));
+}
+
+static uint8_t sbox_inv(uint8_t b){
+	uint8_t sb[]={0x5, 0xE, 0xF, 0x8, 
+				  0xC, 0x1, 0x2, 0xD, 
+				  0xB, 0x4, 0x6, 0x3, 
+				  0x0, 0x7, 0x9, 0xA };
+	return (((sb[b>>4])<<4)|(sb[b&0xf]));
+}
+
+#define SHR_O(a) c=(a)&1; (a)>>=1;
+#define SHR_I(a) (a)=(c?0x8000:0x0000) | ((a)>>1);
+
+static void p(uint16_t* o, uint8_t* i){
+	uint8_t c;
+	uint8_t m,n;
+	for(m=0; m<8; ++m){
+		for(n=0; n<2; ++n){
+			SHR_O(i[m]);
+			SHR_I(o[0]);
+			SHR_O(i[m]);
+			SHR_I(o[1]);
+			SHR_O(i[m]);
+			SHR_I(o[2]);
+			SHR_O(i[m]);
+			SHR_I(o[3]);
+		}
+	}
+}
+
+static void p_inv(uint8_t* o, uint8_t* i){
+	uint8_t tmp[8];
+	p((uint16_t*)tmp, i);
+	p((uint16_t*)o, tmp);
+}
+
+void present_init(const uint8_t* key, uint8_t keysize_b, present_ctx_t* ctx){
+	uint8_t buffer[10], tmp[2];
+	uint8_t i;
+	memcpy(buffer, key, 10);
+	memcpy(&(ctx->k[0]), buffer+2, 8);
+	for(i=1; i<32; ++i){
+		/* rotate buffer 19 right */
+		memcpy(tmp, buffer, 2);
+		memmove(buffer, buffer+2, 8);
+		memcpy(buffer+8, tmp, 2);
+		 /* three shifts to do*/
+		tmp[1]=buffer[0];
+		*((uint64_t*)buffer)>>=3;
+		*((uint16_t*)(buffer+8))>>=3;
+		buffer[9] |= tmp[1]<<5;
+		buffer[7] |= tmp[0]<<5;
+		/* rotating done now substitution */
+		buffer[9] = (sbox(buffer[9])&0xF0) | ((buffer[9])&0x0F);
+		/* xor with round counter */
+		*((uint16_t*)(buffer+1)) ^= (uint16_t)i<<7;
+		memcpy(&(ctx->k[i]), buffer+2, 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];
+		 for(j=0; j<8; ++j){
+		 	tmp[j] = sbox(((uint8_t*)buffer)[j]);
+		 }
+		 p((uint16_t*)buffer, tmp);
+	}
+	*((uint64_t*)buffer) ^= ctx->k[31];
+}
+
+
+void present_dec(void* buffer, present_ctx_t* ctx){
+	uint8_t j,tmp[8];
+	int8_t i;
+	*((uint64_t*)buffer) ^= ctx->k[31];
+
+	for(i=30; i>=0; --i){ 
+		p_inv(tmp, (uint8_t*)buffer);
+		for(j=0; j<8; ++j){
+		 	((uint8_t*)buffer)[j] = sbox_inv(tmp[j]);
+		}
+		*((uint64_t*)buffer) ^= ctx->k[i];
+	}
+}