modified structure

[avr-crypto-lib.git] / rc5 / rc5.c

diff --git a/rc5/rc5.c b/rc5/rc5.c
new file mode 100644 (file)
index 0000000..441f61d
--- /dev/null
+++ b/rc5/rc5.c
@@ -0,0 +1,98 @@
+/* rc5.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/>.
+*/
+/* rc5.c a C implementation of RC5 for AVR microcontrollers
+ * 
+ * author: Daniel Otte 
+ * email:  daniel.otte@rub.de
+ * license: GPLv3
+ * 
+ * this implementation is limited to 64bit blocks and a maximum of 255 rounds
+ * 
+ */
+
+#include <stdint.h>
+#include <stdlib.h> /* malloc() & free() */
+#include <string.h> /* memset() & memcpy() */
+#include "rc5.h" 
+ 
+
+#define A (((uint32_t*)buffer)[0])
+#define B (((uint32_t*)buffer)[1])
+#define ROTL32(v,n) (((v)<<(n))|((v)>>(32-(n))))
+#define ROTR32(v,n) (((v)>>(n))|((v)<<(32-(n))))
+
+void rc5_enc(void* buffer, const rc5_ctx_t* ctx){
+       uint8_t i;
+       A += ctx->s[0];
+       B += ctx->s[1];
+       for(i=0; i<ctx->rounds; ++i){
+               A = ROTL32(A^B, B&31) + ctx->s[(i+1)*2+0];
+               B = ROTL32(A^B, A&31) + ctx->s[(i+1)*2+1];
+       } 
+}
+
+void rc5_dec(void* buffer, const rc5_ctx_t* ctx){
+       uint8_t i;
+       for(i=ctx->rounds; i>0; --i){
+               B = ROTR32(B - ctx->s[i*2+1], A&31) ^ A;
+               A = ROTR32(A - ctx->s[i*2+0], B&31) ^ B;
+       } 
+       B -= ctx->s[1];
+       A -= ctx->s[0];
+}
+/*
+P32 = 10110111111000010101000101100011 = b7e15163
+Q32 = 10011110001101110111100110111001 = 9e3779b9
+*/
+#define P32 0xb7e15163
+#define Q32 0x9e3779b9
+
+
+void rc5_init(void* key, uint16_t keysize_b, uint8_t rounds, rc5_ctx_t* ctx){
+       uint16_t c,n,m,j,i,t;
+       uint32_t a,b,l[(keysize_b+31)/32];
+       ctx->rounds = rounds;
+       t=2*(rounds+1);
+       c=(keysize_b+31)/32;
+       ctx->s = malloc(t*sizeof(uint32_t));
+       
+       memset(l, 0, sizeof(uint32_t)*c);
+       memcpy(l, key, (keysize_b+7)/8);
+       
+       ctx->s[0] = P32;
+       for(i=1; i<t; ++i){
+               ctx->s[i] = ctx->s[i-1] + Q32;
+       }
+       
+       m = ((t>c)?t:c)*3;
+       i=j=0;
+       a=b=0;
+       for(n=0; n<m; ++n){
+               a=ctx->s[i]=ROTL32(ctx->s[i]+a+b, 3);
+               b=l[j]=ROTL32(l[j]+a+b, (a+b)&31);
+               i=(i+1)%t;
+               j=(j+1)%c;
+       }
+}
+
+void rc5_free(rc5_ctx_t* ctx){
+       if(ctx->s)
+               free(ctx->s);
+}
+