3 This file is part of the AVR-Crypto-Lib.
4 Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
19 /* rc5.c a C implementation of RC5 for AVR microcontrollers
22 * email: daniel.otte@rub.de
25 * this implementation is limited to 64bit blocks and a maximum of 255 rounds
30 #include <stdlib.h> /* malloc() & free() */
31 #include <string.h> /* memset() & memcpy() */
35 #define A (((uint32_t*)buffer)[0])
36 #define B (((uint32_t*)buffer)[1])
37 #define ROTL32(v,n) (((v)<<(n))|((v)>>(32-(n))))
38 #define ROTR32(v,n) (((v)>>(n))|((v)<<(32-(n))))
40 void rc5_enc(void* buffer, const rc5_ctx_t* ctx){
44 for(i=0; i<ctx->rounds; ++i){
45 A = ROTL32(A^B, B&31) + ctx->s[(i+1)*2+0];
46 B = ROTL32(A^B, A&31) + ctx->s[(i+1)*2+1];
50 void rc5_dec(void* buffer, const rc5_ctx_t* ctx){
52 for(i=ctx->rounds; i>0; --i){
53 B = ROTR32(B - ctx->s[i*2+1], A&31) ^ A;
54 A = ROTR32(A - ctx->s[i*2+0], B&31) ^ B;
60 P32 = 10110111111000010101000101100011 = b7e15163
61 Q32 = 10011110001101110111100110111001 = 9e3779b9
63 #define P32 0xb7e15163
64 #define Q32 0x9e3779b9
67 void rc5_init(void* key, uint16_t keysize_b, uint8_t rounds, rc5_ctx_t* ctx){
69 uint32_t a,b,l[(keysize_b+31)/32];
73 ctx->s = malloc(t*sizeof(uint32_t));
75 memset(l, 0, sizeof(uint32_t)*c);
76 memcpy(l, key, (keysize_b+7)/8);
80 ctx->s[i] = ctx->s[i-1] + Q32;
87 a=ctx->s[i]=ROTL32(ctx->s[i]+a+b, 3);
88 b=l[j]=ROTL32(l[j]+a+b, (a+b)&31);
94 void rc5_free(rc5_ctx_t* ctx){