75 lines
1.9 KiB
C
75 lines
1.9 KiB
C
/* threefish256_enc.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2009 Daniel Otte (daniel.otte@rub.de)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* \author Daniel Otte
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* \email daniel.otte@rub.de
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* \date 2009-03-12
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* \license GPLv3 or later
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*
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*
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*
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*/
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#include <stdint.h>
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#include <string.h>
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#include "threefish.h"
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#define X(a) (((uint64_t*)data)[(a)])
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static
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void permute_4(void* data){
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uint64_t t;
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t = X(1);
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X(1) = X(3);
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X(3) = t;
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}
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#define K(s) (((uint64_t*)key)[(s)])
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#define T(s) (((uint64_t*)tweak)[(s)])
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static
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void add_key_4(void* data, const threefish256_ctx_t* ctx, uint8_t s){
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X(0) -= ctx->k[(s+0)%5];
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X(1) -= ctx->k[(s+1)%5] + ctx->t[s%3];
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X(2) -= ctx->k[(s+2)%5] + ctx->t[(s+1)%3];
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X(3) -= ctx->k[(s+3)%5] + s;
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}
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void threefish256_dec(void* data, const threefish256_ctx_t* ctx){
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uint8_t i=0,s=18;
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/* old constans, changed at round 2 of the SHA-3 contest
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uint8_t r0[8] = {59, 11, 53, 26, 58, 13, 36, 5};
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uint8_t r1[8] = {50, 42, 35, 20, 44, 46, 28, 56};
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*/
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uint8_t r0[8] = { 32, 58, 46, 25, 5, 23, 52, 14};
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uint8_t r1[8] = { 32, 22, 12, 33, 37, 40, 57, 16};
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do{
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if(i%4==0){
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add_key_4(data, ctx, s);
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--s;
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}
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permute_4(data);
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threefish_invmix(data, r0[i%8]);
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threefish_invmix((uint8_t*)data + 16, r1[i%8]);
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++i;
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}while(i!=72);
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add_key_4(data, ctx, s);
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}
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