new makefile and modified build process

[avr-crypto-lib.git] / skein / threefish256_dec_cstub.c

diff --git a/skein/threefish256_dec_cstub.c b/skein/threefish256_dec_cstub.c
new file mode 100644 (file)
index 0000000..1d89756
--- /dev/null
+++ b/skein/threefish256_dec_cstub.c
@@ -0,0 +1,66 @@
+/* threefish256_enc.c */
+/*
+    This file is part of the AVR-Crypto-Lib.
+    Copyright (C) 2009  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/>.
+*/
+/*
+ * \author  Daniel Otte
+ * \email   daniel.otte@rub.de
+ * \date    2009-03-12
+ * \license GPLv3 or later
+ * 
+ * 
+ * 
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include "threefish.h"
+
+#define X(a) (((uint64_t*)data)[(a)])
+static
+void permute_4(void* data){
+       uint64_t t;
+       t = X(1);
+       X(1) = X(3);
+       X(3) = t;
+}
+
+static
+void add_key_4(void* data, const threefish256_ctx_t* ctx, uint8_t s){
+       X(0) -= ctx->k[(s+0)%5];
+       X(1) -= ctx->k[(s+1)%5] + ctx->t[s%3];
+       X(2) -= ctx->k[(s+2)%5] + ctx->t[(s+1)%3];
+       X(3) -= ctx->k[(s+3)%5] + s;
+}
+
+void threefish256_dec(void* data, const threefish256_ctx_t* ctx){
+       uint8_t i=0,s=18;
+       uint8_t r0[8] = {0x73, 0x13, 0x7b, 0x32, 0x72, 0x2b, 0x44, 0x1b}; 
+       uint8_t r1[8] = {0x62, 0x52, 0x43, 0x24, 0x54, 0x6a, 0x34, 0x70};
+       do{
+               if(i%4==0){
+                       add_key_4(data, ctx, s);
+                       --s;
+               }
+               permute_4(data);
+               threefish_invmix(data, r0[i%8]);
+               threefish_invmix((uint8_t*)data + 16, r1[i%8]);
+               ++i;
+       }while(i!=72);
+       add_key_4(data, ctx, s);
+}
+