/* serpent-sboxes.c */
/*
    This file is part of the AVR-Crypto-Lib.
    Copyright (C) 2006-2015 Daniel Otte (bg@nerilex.org)

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
/* serpent-sboxes.c
 * a non-bitsliced implementation of the serpent sboxes
 * author: Daniel Otte 
 * email:  bg@nerilex.org
 * license: GPLv3
 */

#include <stdint.h>
#include <string.h> /* memset() */
#include <avr/pgmspace.h>
#include "serpent-sboxes.h"

const uint8_t sbox[] PROGMEM = {
 0x38, 0xF1, 0xA6, 0x5B, 0xED, 0x42, 0x70, 0x9C,
 0xFC, 0x27, 0x90, 0x5A, 0x1B, 0xE8, 0x6D, 0x34, 
 0x86, 0x79, 0x3C, 0xAF, 0xD1, 0xE4, 0x0B, 0x52,
 0x0F, 0xB8, 0xC9, 0x63, 0xD1, 0x24, 0xA7, 0x5E,
 0x1F, 0x83, 0xC0, 0xB6, 0x25, 0x4A, 0x9E, 0x7D,
 0xF5, 0x2B, 0x4A, 0x9C, 0x03, 0xE8, 0xD6, 0x71,
 0x72, 0xC5, 0x84, 0x6B, 0xE9, 0x1F, 0xD3, 0xA0,
 0x1D, 0xF0, 0xE8, 0x2B, 0x74, 0xCA, 0x93, 0x56,
/* now the inverted sboxes */
 0xD3, 0xB0, 0xA6, 0x5C, 0x1E, 0x47, 0xF9, 0x82,
 0x58, 0x2E, 0xF6, 0xC3, 0xB4, 0x79, 0x1D, 0xA0,
 0xC9, 0xF4, 0xBE, 0x12, 0x03, 0x6D, 0x58, 0xA7,
 0x09, 0xA7, 0xBE, 0x6D, 0x35, 0xC2, 0x48, 0xF1,
 0x50, 0x83, 0xA9, 0x7E, 0x2C, 0xB6, 0x4F, 0xD1,
 0x8F, 0x29, 0x41, 0xDE, 0xB6, 0x53, 0x7C, 0xA0,
 0xFA, 0x1D, 0x53, 0x60, 0x49, 0xE7, 0x2C, 0x8B,
 0x30, 0x6D, 0x9E, 0xF8, 0x5C, 0xB7, 0xA1, 0x42
};        
         

#define SHR_O(a) c=(a)&1; ((a) = (a)>>1)
#define SHR_I(a) ((a) = (c?0x80:0x00)| ((a)>>1))

static void serpent_ip(uint32_t *i, uint8_t *o){
	uint8_t c; // carry 
	uint8_t n,m;
	memset(o, 0, 16);
	for(n=0; n<16; ++n){
		for(m=0; m<2; ++m){
		SHR_O(i[0]);
		SHR_I(o[n]);
		SHR_O(i[1]);
		SHR_I(o[n]);
		SHR_O(i[2]);
		SHR_I(o[n]);
		SHR_O(i[3]);
		SHR_I(o[n]);
		}
	}
}

#undef SHR_I
#define SHR_I(a) ((a) = (c?0x80000000L:0x00L)| ((a)>>1)) /* we use 32-bit words here */

static void serpent_fp(uint32_t *i, uint32_t *o){
	uint8_t c; // carry 
	uint8_t n,m;
	memset(o, 0, 16);
	for(n=0; n<4; ++n){
		for(m=0; m<8; ++m){
		SHR_O(i[n]);
		SHR_I(o[0]);
		SHR_O(i[n]);
		SHR_I(o[1]);
		SHR_O(i[n]);
		SHR_I(o[2]);
		SHR_O(i[n]);
		SHR_I(o[3]);
		}
	}
}

/******************************************************************************/
static void sbox128x(uint8_t box, void *w){
	uint8_t sb[16];
	uint8_t i,t,x;
	box &= 0x0f;
	/* load sbox */
	for(i=0; i<8; ++i){
		t = pgm_read_byte(sbox + box*8 + i);
		sb[2*i+0]=t>>4;
		sb[2*i+1]=t&0xf;
	}
	uint8_t o[16];
	serpent_ip(w,o);
	
	for(i=0; i<16; ++i){
		t = ((uint8_t*)o)[i];
		x = sb[t>>4];
		x <<= 4;
		x |= sb[t&0xf];
		((uint8_t*)o)[i] = x;
	}
	serpent_fp((uint32_t*)o, w);
}

void sbox128(void * w, uint8_t box){
	sbox128x(box&0x7, w);
}


void inv_sbox128(void * w, uint8_t box){
	sbox128x(((box&0x7)|0x8), w);
}