67 lines
1.7 KiB
C
67 lines
1.7 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) 2006-2015 Daniel Otte (bg@nerilex.org)
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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 bg@nerilex.org
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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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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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uint8_t r0[8] = {0x73, 0x13, 0x7b, 0x32, 0x72, 0x2b, 0x44, 0x1b};
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uint8_t r1[8] = {0x62, 0x52, 0x43, 0x24, 0x54, 0x6a, 0x34, 0x70};
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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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