89 lines
2.2 KiB
C
89 lines
2.2 KiB
C
/* threefish512_dec.c */
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/*
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This file is part of the ARM-Crypto-Lib.
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Copyright (C) 2006-2010 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 2009-03-22
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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_inv8(void* data){
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uint64_t t;
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t = X(6);
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X(6) = X(4);
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X(4) = X(2);
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X(2) = X(0);
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X(0) = t;
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t = X(7);
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X(7) = 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_8(void* data, const threefish512_ctx_t* ctx, uint8_t s){
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uint8_t i;
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for(i=0; i<5; ++i){
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X(i) -= ctx->k[(s+i)%9];
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}
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X(5) -= ctx->k[(s+5)%9] + ctx->t[s%3];
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X(6) -= ctx->k[(s+6)%9] + ctx->t[(s+1)%3];
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X(7) -= ctx->k[(s+7)%9] + s;
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}
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void threefish512_dec(void* data, const threefish512_ctx_t* ctx){
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uint8_t i=0,s=18;
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/* old round constants
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uint8_t r0[8] = {33, 29, 39, 33, 26, 34, 48, 38};
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uint8_t r1[8] = {51, 26, 27, 49, 12, 14, 20, 30};
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uint8_t r2[8] = {39, 11, 41, 8, 58, 15, 43, 50};
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uint8_t r3[8] = {35, 9, 14, 42, 7, 27, 31, 53};
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*/
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uint8_t r0[8] = { 8, 25, 13, 39, 44, 17, 33, 46};
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uint8_t r1[8] = { 35, 29, 50, 30, 9, 49, 27, 36};
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uint8_t r2[8] = { 56, 39, 10, 34, 54, 36, 14, 19};
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uint8_t r3[8] = { 22, 43, 17, 24, 56, 39, 42, 37};
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do{
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if(i%4==0){
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add_key_8(data, ctx, s);
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--s;
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}
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permute_inv8(data);
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threefish_invmix((uint8_t*)data + 0, r0[i%8]);
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threefish_invmix((uint8_t*)data + 16, r1[i%8]);
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threefish_invmix((uint8_t*)data + 32, r2[i%8]);
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threefish_invmix((uint8_t*)data + 48, r3[i%8]);
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++i;
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}while(i!=72);
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add_key_8(data, ctx, s);
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}
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