modified structure

[avr-crypto-lib.git] / xtea / xtea.c

diff --git a/xtea/xtea.c b/xtea/xtea.c
new file mode 100644 (file)
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+++ b/xtea/xtea.c
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+/* xtea.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/>.
+*/
+/** 
+ * \file       xtea.c
+ * \brief      XTEA implemantation 
+ *   copy'n'pasted from http://en.wikipedia.org/wiki/XTEA
+ *   and slightly modified
+ */
+ 
+#include <stdint.h> 
+ 
+
+void xtea_enc(void* dest, const void* v, const void* k) {
+    uint8_t i;
+    uint32_t v0=((uint32_t*)v)[0], v1=((uint32_t*)v)[1];
+    uint32_t sum=0, delta=0x9E3779B9;
+    for(i=0; i<32; i++) {
+        v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + ((uint32_t*)k)[sum & 3]);
+        sum += delta;
+        v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + ((uint32_t*)k)[sum>>11 & 3]);
+    }
+    ((uint32_t*)dest)[0]=v0; ((uint32_t*)dest)[1]=v1;
+}
+
+void xtea_dec(void* dest, const void* v, const void* k) {
+    uint8_t i;
+    uint32_t v0=((uint32_t*)v)[0], v1=((uint32_t*)v)[1];
+    uint32_t sum=0xC6EF3720, delta=0x9E3779B9;
+    for(i=0; i<32; i++) {
+        v1 -= ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + ((uint32_t*)k)[sum>>11 & 3]);
+        sum -= delta;
+        v0 -= ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + ((uint32_t*)k)[sum & 3]);
+    }
+    ((uint32_t*)dest)[0]=v0; ((uint32_t*)dest)[1]=v1;
+}
+
+