144 lines
3.8 KiB
C
144 lines
3.8 KiB
C
/* salsa20.c */
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/*
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This file is part of the AVR-Crypto-Lib.
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Copyright (C) 2006-2011 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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#include <stdint.h>
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#include <string.h>
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#include <avr/pgmspace.h>
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#include "salsa20.h"
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#define ROTL32(a,n) (((a)<<(n))|((a)>>(32-(n))))
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static
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void quaterround(uint32_t *a, uint32_t *b, uint32_t *c, uint32_t *d){
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*b ^= ROTL32(*a + *d, 7);
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*c ^= ROTL32(*b + *a, 9);
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*d ^= ROTL32(*c + *b, 13);
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*a ^= ROTL32(*d + *c, 18);
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}
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static
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void rowround(uint32_t *a){
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quaterround(a+ 0, a+ 1, a+ 2, a+ 3);
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quaterround(a+ 5, a+ 6, a+ 7, a+ 4);
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quaterround(a+10, a+11, a+ 8, a+ 9);
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quaterround(a+15, a+12, a+13, a+14);
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}
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static
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void columnround(uint32_t *a){
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quaterround(a+ 0, a+ 4, a+ 8, a+12);
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quaterround(a+ 5, a+ 9, a+13, a+ 1);
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quaterround(a+10, a+14, a+ 2, a+ 6);
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quaterround(a+15, a+ 3, a+ 7, a+11);
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}
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static
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void doubleround(uint32_t *a){
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columnround(a);
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rowround(a);
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}
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void salsa20_hash(uint32_t *a){
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uint8_t i;
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uint32_t b[16];
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memcpy(b, a, 64);
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for(i=0; i<10; ++i){
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doubleround(a);
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}
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for(i=0; i<16; ++i){
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a[i] += b[i];
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}
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}
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const uint8_t sigma[] PROGMEM = {'e','x','p','a','n','d',' ','3','2','-','b','y','t','e',' ','k'};
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const uint8_t theta[] PROGMEM = {'e','x','p','a','n','d',' ','1','6','-','b','y','t','e',' ','k'};
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void salsa_k32(uint32_t *dest, const uint32_t *k, const uint32_t *n){
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memcpy_P(dest+ 0, sigma+ 0, 4);
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memcpy( dest+ 4, k+ 0, 16);
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memcpy_P(dest+20, sigma+ 4, 4);
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memcpy( dest+24, n+ 0, 16);
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memcpy_P(dest+40, sigma+ 8, 4);
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memcpy( dest+44, k+16, 16);
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memcpy_P(dest+60, sigma+12, 4);
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salsa20_hash(dest);
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}
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void salsa_k16(uint32_t *dest, const uint32_t *k, const uint32_t *n){
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memcpy_P(dest+ 0, theta+ 0, 4);
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memcpy( dest+ 4, k+ 0, 16);
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memcpy_P(dest+20, theta+ 4, 4);
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memcpy( dest+24, n+ 0, 16);
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memcpy_P(dest+40, theta+ 8, 4);
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memcpy( dest+44, k+ 0, 16);
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memcpy_P(dest+60, theta+12, 4);
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salsa20_hash(dest);
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}
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void salsa20_genBlock256(void *dest, const void *k, const void *iv, uint64_t i){
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uint32_t n[4];
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memcpy(n, iv, 8);
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memcpy(n+8, &i, 8);
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salsa_k32((uint32_t*)dest, (uint32_t*)k, n);
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}
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void salsa20_genBlock128(void *dest, const void *k, const void *iv, uint64_t i){
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uint32_t n[4];
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memcpy(n, iv, 8);
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memcpy(n+8, &i, 8);
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salsa_k16((uint32_t*)dest, (uint32_t*)k, n);
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}
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void salsa20_init(void *key, uint16_t keylength_b, void *iv, salsa20_ctx_t *ctx){
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if(keylength_b==256){
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memcpy_P((ctx->a.v8+ 0), sigma+ 0, 4);
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memcpy_P((ctx->a.v8+20), sigma+ 4, 4);
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memcpy_P((ctx->a.v8+40), sigma+ 8, 4);
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memcpy( (ctx->a.v8+44), (uint8_t*)key+16, 16);
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memcpy_P((ctx->a.v8+60), sigma+12, 4);
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}else{
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memcpy_P((ctx->a.v8+ 0), theta+ 0, 4);
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memcpy_P((ctx->a.v8+20), theta+ 4, 4);
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memcpy_P((ctx->a.v8+40), theta+ 8, 4);
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memcpy( (ctx->a.v8+44), (uint8_t*)key+ 0, 16);
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memcpy_P((ctx->a.v8+60), theta+12, 4);
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}
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memcpy( (ctx->a.v8+ 4), key, 16);
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memset( (ctx->a.v8+24), 0, 16);
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if(iv){
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memcpy( (ctx->a.v8+24), iv, 8);
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}
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ctx->buffer_idx=64;
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}
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uint8_t salsa20_gen(salsa20_ctx_t *ctx){
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if(ctx->buffer_idx==64){
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memcpy(ctx->buffer, ctx->a.v8, 64);
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salsa20_hash((uint32_t*)(ctx->buffer));
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ctx->a.v64[4] += 1;
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ctx->buffer_idx = 0;
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}
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return ctx->buffer[ctx->buffer_idx++];
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}
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