// kuznechik_128bit.c
// 04-Jan-15  Markku-Juhani O. Saarinen <mjos@iki.fi>

// Basic 128-bit version without platform - specific optimizations

// Conforms to included doc/GOSTR-bsh.pdf file, which has an internal
// date of September 2, 2014.

#include "kuznechik_128bit.h"

#ifndef __SSE4_1__
#error "This version requires __SSE4_1__"
#endif

#include <mmintrin.h>
#include <emmintrin.h>
#include <smmintrin.h>

// The S-Box from section 5.1.1

static const uint8_t kuz_pi[0x100] = {
	0xFC, 0xEE, 0xDD, 0x11, 0xCF, 0x6E, 0x31, 0x16, 	// 00..07
	0xFB, 0xC4, 0xFA, 0xDA, 0x23, 0xC5, 0x04, 0x4D, 	// 08..0F
	0xE9, 0x77, 0xF0, 0xDB, 0x93, 0x2E, 0x99, 0xBA, 	// 10..17
	0x17, 0x36, 0xF1, 0xBB, 0x14, 0xCD, 0x5F, 0xC1, 	// 18..1F
	0xF9, 0x18, 0x65, 0x5A, 0xE2, 0x5C, 0xEF, 0x21, 	// 20..27
	0x81, 0x1C, 0x3C, 0x42, 0x8B, 0x01, 0x8E, 0x4F, 	// 28..2F
	0x05, 0x84, 0x02, 0xAE, 0xE3, 0x6A, 0x8F, 0xA0, 	// 30..37
	0x06, 0x0B, 0xED, 0x98, 0x7F, 0xD4, 0xD3, 0x1F, 	// 38..3F
	0xEB, 0x34, 0x2C, 0x51, 0xEA, 0xC8, 0x48, 0xAB, 	// 40..47
	0xF2, 0x2A, 0x68, 0xA2, 0xFD, 0x3A, 0xCE, 0xCC, 	// 48..4F
	0xB5, 0x70, 0x0E, 0x56, 0x08, 0x0C, 0x76, 0x12, 	// 50..57
	0xBF, 0x72, 0x13, 0x47, 0x9C, 0xB7, 0x5D, 0x87, 	// 58..5F
	0x15, 0xA1, 0x96, 0x29, 0x10, 0x7B, 0x9A, 0xC7, 	// 60..67
	0xF3, 0x91, 0x78, 0x6F, 0x9D, 0x9E, 0xB2, 0xB1, 	// 68..6F
	0x32, 0x75, 0x19, 0x3D, 0xFF, 0x35, 0x8A, 0x7E, 	// 70..77
	0x6D, 0x54, 0xC6, 0x80, 0xC3, 0xBD, 0x0D, 0x57, 	// 78..7F
	0xDF, 0xF5, 0x24, 0xA9, 0x3E, 0xA8, 0x43, 0xC9, 	// 80..87
	0xD7, 0x79, 0xD6, 0xF6, 0x7C, 0x22, 0xB9, 0x03, 	// 88..8F
	0xE0, 0x0F, 0xEC, 0xDE, 0x7A, 0x94, 0xB0, 0xBC, 	// 90..97
	0xDC, 0xE8, 0x28, 0x50, 0x4E, 0x33, 0x0A, 0x4A, 	// 98..9F
	0xA7, 0x97, 0x60, 0x73, 0x1E, 0x00, 0x62, 0x44, 	// A0..A7
	0x1A, 0xB8, 0x38, 0x82, 0x64, 0x9F, 0x26, 0x41, 	// A8..AF
	0xAD, 0x45, 0x46, 0x92, 0x27, 0x5E, 0x55, 0x2F, 	// B0..B7
	0x8C, 0xA3, 0xA5, 0x7D, 0x69, 0xD5, 0x95, 0x3B, 	// B8..BF
	0x07, 0x58, 0xB3, 0x40, 0x86, 0xAC, 0x1D, 0xF7, 	// C0..C7
	0x30, 0x37, 0x6B, 0xE4, 0x88, 0xD9, 0xE7, 0x89, 	// C8..CF
	0xE1, 0x1B, 0x83, 0x49, 0x4C, 0x3F, 0xF8, 0xFE, 	// D0..D7
	0x8D, 0x53, 0xAA, 0x90, 0xCA, 0xD8, 0x85, 0x61, 	// D8..DF
	0x20, 0x71, 0x67, 0xA4, 0x2D, 0x2B, 0x09, 0x5B, 	// E0..E7
	0xCB, 0x9B, 0x25, 0xD0, 0xBE, 0xE5, 0x6C, 0x52, 	// E8..EF
	0x59, 0xA6, 0x74, 0xD2, 0xE6, 0xF4, 0xB4, 0xC0, 	// F0..F7
	0xD1, 0x66, 0xAF, 0xC2, 0x39, 0x4B, 0x63, 0xB6, 	// F8..FF
};

// Inverse S-Box

static const uint8_t kuz_pi_inv[0x100] = {
	0xA5, 0x2D, 0x32, 0x8F, 0x0E, 0x30, 0x38, 0xC0, 	// 00..07
	0x54, 0xE6, 0x9E, 0x39, 0x55, 0x7E, 0x52, 0x91, 	// 08..0F
	0x64, 0x03, 0x57, 0x5A, 0x1C, 0x60, 0x07, 0x18, 	// 10..17
	0x21, 0x72, 0xA8, 0xD1, 0x29, 0xC6, 0xA4, 0x3F, 	// 18..1F
	0xE0, 0x27, 0x8D, 0x0C, 0x82, 0xEA, 0xAE, 0xB4, 	// 20..27
	0x9A, 0x63, 0x49, 0xE5, 0x42, 0xE4, 0x15, 0xB7, 	// 28..2F
	0xC8, 0x06, 0x70, 0x9D, 0x41, 0x75, 0x19, 0xC9, 	// 30..37
	0xAA, 0xFC, 0x4D, 0xBF, 0x2A, 0x73, 0x84, 0xD5, 	// 38..3F
	0xC3, 0xAF, 0x2B, 0x86, 0xA7, 0xB1, 0xB2, 0x5B, 	// 40..47
	0x46, 0xD3, 0x9F, 0xFD, 0xD4, 0x0F, 0x9C, 0x2F, 	// 48..4F
	0x9B, 0x43, 0xEF, 0xD9, 0x79, 0xB6, 0x53, 0x7F, 	// 50..57
	0xC1, 0xF0, 0x23, 0xE7, 0x25, 0x5E, 0xB5, 0x1E, 	// 58..5F
	0xA2, 0xDF, 0xA6, 0xFE, 0xAC, 0x22, 0xF9, 0xE2, 	// 60..67
	0x4A, 0xBC, 0x35, 0xCA, 0xEE, 0x78, 0x05, 0x6B, 	// 68..6F
	0x51, 0xE1, 0x59, 0xA3, 0xF2, 0x71, 0x56, 0x11, 	// 70..77
	0x6A, 0x89, 0x94, 0x65, 0x8C, 0xBB, 0x77, 0x3C, 	// 78..7F
	0x7B, 0x28, 0xAB, 0xD2, 0x31, 0xDE, 0xC4, 0x5F, 	// 80..87
	0xCC, 0xCF, 0x76, 0x2C, 0xB8, 0xD8, 0x2E, 0x36, 	// 88..8F
	0xDB, 0x69, 0xB3, 0x14, 0x95, 0xBE, 0x62, 0xA1, 	// 90..97
	0x3B, 0x16, 0x66, 0xE9, 0x5C, 0x6C, 0x6D, 0xAD, 	// 98..9F
	0x37, 0x61, 0x4B, 0xB9, 0xE3, 0xBA, 0xF1, 0xA0, 	// A0..A7
	0x85, 0x83, 0xDA, 0x47, 0xC5, 0xB0, 0x33, 0xFA, 	// A8..AF
	0x96, 0x6F, 0x6E, 0xC2, 0xF6, 0x50, 0xFF, 0x5D, 	// B0..B7
	0xA9, 0x8E, 0x17, 0x1B, 0x97, 0x7D, 0xEC, 0x58, 	// B8..BF
	0xF7, 0x1F, 0xFB, 0x7C, 0x09, 0x0D, 0x7A, 0x67, 	// C0..C7
	0x45, 0x87, 0xDC, 0xE8, 0x4F, 0x1D, 0x4E, 0x04, 	// C8..CF
	0xEB, 0xF8, 0xF3, 0x3E, 0x3D, 0xBD, 0x8A, 0x88, 	// D0..D7
	0xDD, 0xCD, 0x0B, 0x13, 0x98, 0x02, 0x93, 0x80, 	// D8..DF
	0x90, 0xD0, 0x24, 0x34, 0xCB, 0xED, 0xF4, 0xCE, 	// E0..E7
	0x99, 0x10, 0x44, 0x40, 0x92, 0x3A, 0x01, 0x26, 	// E8..EF
	0x12, 0x1A, 0x48, 0x68, 0xF5, 0x81, 0x8B, 0xC7, 	// F0..F7
	0xD6, 0x20, 0x0A, 0x08, 0x00, 0x4C, 0xD7, 0x74	 	// F8..FF
};

// Linear vector from sect 5.1.2

static const uint8_t kuz_lvec[16] = {
	0x94, 0x20, 0x85, 0x10, 0xC2, 0xC0, 0x01, 0xFB, 
	0x01, 0xC0, 0xC2, 0x10, 0x85, 0x20, 0x94, 0x01
};

// lookup tables initialized by kuz_init()

static int kuz_initialized = 0;
static __m128i kuz_pil_enc128[16][256];
static __m128i kuz_l_dec128[16][256];
static __m128i kuz_pil_dec128[16][256];

// poly multiplication mod p(x) = x^8 + x^7 + x^6 + x + 1

static uint8_t kuz_mul_gf256(uint8_t x, uint8_t y)
{
	uint8_t z;
	
	z = 0;
	while (y) {		
		if (y & 1)
			z ^= x;
		x = (x << 1) ^ (x & 0x80 ? 0xC3 : 0x00);
		y >>= 1;
	}
		
	return z;
}

// (slow) linear operation l

static void kuz_l(w128_t *w)
{
	int i, j;
	uint8_t x;
	
	// 16 rounds
	for (j = 0; j < 16; j++) {

		// An LFSR with 16 elements from GF(2^8)
		x = w->b[15];	// since lvec[15] = 1

		for (i = 14; i >= 0; i--) {
			w->b[i + 1] = w->b[i];
			x ^= kuz_mul_gf256(w->b[i], kuz_lvec[i]);
		}
		w->b[0] = x;
	}
}

// inverse of linear operation l

static void kuz_l_inv(w128_t *w)
{
	int i, j;
	uint8_t x;
	
	// 16 rounds
	for (j = 0; j < 16; j++) {

		x = w->b[0];
		for (i = 0; i < 15; i++) {
			w->b[i] = w->b[i + 1];	
			x ^= kuz_mul_gf256(w->b[i], kuz_lvec[i]);
		}
		w->b[15] = x;
	}
}

// key setup

void kuz_set_encrypt_key(kuz_key_t *kuz, const uint8_t key[32])
{
	int i, j;
	w128_t c, x, y, z;
		
	if (!kuz_initialized)
		kuz_init();
		
	for (i = 0; i < 16; i++) {
		// this will be have to changed for little-endian systems
		x.b[i] = key[i];
		y.b[i] = key[i + 16];
	}

	kuz->k[0].q[0] = x.q[0];
	kuz->k[0].q[1] = x.q[1];
	kuz->k[1].q[0] = y.q[0];
	kuz->k[1].q[1] = y.q[1];

	for (i = 1; i <= 32; i++) {

		// C Value
		c.q[0] = 0;
		c.q[1] = 0;
		c.b[15] = i;		// load round in lsb
		kuz_l(&c);
		
		z.q[0] = x.q[0] ^ c.q[0];
		z.q[1] = x.q[1] ^ c.q[1];
		for (j = 0; j < 16; j++)
			z.b[j] = kuz_pi[z.b[j]];
		kuz_l(&z);
		z.q[0] ^= y.q[0];
		z.q[1] ^= y.q[1];
		
		y.q[0] = x.q[0];
		y.q[1] = x.q[1];

		x.q[0] = z.q[0];
		x.q[1] = z.q[1];

		if ((i & 7) == 0) {
			kuz->k[(i >> 2)].q[0] = x.q[0];
			kuz->k[(i >> 2)].q[1] = x.q[1];
			kuz->k[(i >> 2) + 1].q[0] = y.q[0];
			kuz->k[(i >> 2) + 1].q[1] = y.q[1];
		}
	}
}

// these two funcs are identical in the simple implementation

void kuz_set_decrypt_key(kuz_key_t *kuz, const uint8_t key[32])
{
	int i;

	kuz_set_encrypt_key(kuz, key);

	for (i = 1; i < 10; i++)
		kuz_l_inv(&kuz->k[i]);
}

// encrypt a block - 128 bit way

void kuz_encrypt_block(kuz_key_t *key, void *blk)
{
	int i;
	__m128i x;

	x = *((__m128i *) blk);

	for (i = 0; i < 9; i++) {
		x ^= *((__m128i *) &key->k[i]);
		x = kuz_pil_enc128[ 0][((uint8_t *) &x)[ 0]] ^
			kuz_pil_enc128[ 1][((uint8_t *) &x)[ 1]] ^
			kuz_pil_enc128[ 2][((uint8_t *) &x)[ 2]] ^
			kuz_pil_enc128[ 3][((uint8_t *) &x)[ 3]] ^
			kuz_pil_enc128[ 4][((uint8_t *) &x)[ 4]] ^
			kuz_pil_enc128[ 5][((uint8_t *) &x)[ 5]] ^
			kuz_pil_enc128[ 6][((uint8_t *) &x)[ 6]] ^
			kuz_pil_enc128[ 7][((uint8_t *) &x)[ 7]] ^
			kuz_pil_enc128[ 8][((uint8_t *) &x)[ 8]] ^
			kuz_pil_enc128[ 9][((uint8_t *) &x)[ 9]] ^
			kuz_pil_enc128[10][((uint8_t *) &x)[10]] ^
			kuz_pil_enc128[11][((uint8_t *) &x)[11]] ^
			kuz_pil_enc128[12][((uint8_t *) &x)[12]] ^
			kuz_pil_enc128[13][((uint8_t *) &x)[13]] ^
			kuz_pil_enc128[14][((uint8_t *) &x)[14]] ^
			kuz_pil_enc128[15][((uint8_t *) &x)[15]];
			
	}
	x ^= *((__m128i *) &key->k[9]);

	*((__m128i *) blk) = x;
}

// decrypt a block - 128 bit way

void kuz_decrypt_block(kuz_key_t *key, void *blk)
{
	int i, j;
	__m128i x;

	x = *((__m128i *) blk);
	
	x = kuz_l_dec128[ 0][((uint8_t *) &x)[ 0]] ^
		kuz_l_dec128[ 1][((uint8_t *) &x)[ 1]] ^
		kuz_l_dec128[ 2][((uint8_t *) &x)[ 2]] ^
		kuz_l_dec128[ 3][((uint8_t *) &x)[ 3]] ^
		kuz_l_dec128[ 4][((uint8_t *) &x)[ 4]] ^
		kuz_l_dec128[ 5][((uint8_t *) &x)[ 5]] ^
		kuz_l_dec128[ 6][((uint8_t *) &x)[ 6]] ^
		kuz_l_dec128[ 7][((uint8_t *) &x)[ 7]] ^
		kuz_l_dec128[ 8][((uint8_t *) &x)[ 8]] ^
		kuz_l_dec128[ 9][((uint8_t *) &x)[ 9]] ^
		kuz_l_dec128[10][((uint8_t *) &x)[10]] ^
		kuz_l_dec128[11][((uint8_t *) &x)[11]] ^
		kuz_l_dec128[12][((uint8_t *) &x)[12]] ^
		kuz_l_dec128[13][((uint8_t *) &x)[13]] ^
		kuz_l_dec128[14][((uint8_t *) &x)[14]] ^
		kuz_l_dec128[15][((uint8_t *) &x)[15]];

	for (i = 9; i > 1; i--) {
		x ^= *((__m128i *) &key->k[i]);
		x = kuz_pil_dec128[ 0][((uint8_t *) &x)[ 0]] ^
			kuz_pil_dec128[ 1][((uint8_t *) &x)[ 1]] ^
			kuz_pil_dec128[ 2][((uint8_t *) &x)[ 2]] ^
			kuz_pil_dec128[ 3][((uint8_t *) &x)[ 3]] ^
			kuz_pil_dec128[ 4][((uint8_t *) &x)[ 4]] ^
			kuz_pil_dec128[ 5][((uint8_t *) &x)[ 5]] ^
			kuz_pil_dec128[ 6][((uint8_t *) &x)[ 6]] ^
			kuz_pil_dec128[ 7][((uint8_t *) &x)[ 7]] ^
			kuz_pil_dec128[ 8][((uint8_t *) &x)[ 8]] ^
			kuz_pil_dec128[ 9][((uint8_t *) &x)[ 9]] ^
			kuz_pil_dec128[10][((uint8_t *) &x)[10]] ^
			kuz_pil_dec128[11][((uint8_t *) &x)[11]] ^
			kuz_pil_dec128[12][((uint8_t *) &x)[12]] ^
			kuz_pil_dec128[13][((uint8_t *) &x)[13]] ^
			kuz_pil_dec128[14][((uint8_t *) &x)[14]] ^
			kuz_pil_dec128[15][((uint8_t *) &x)[15]];
	}
	x ^= *((__m128i *) &key->k[1]);
	for (j = 0; j < 16; j++)
		((uint8_t *) &x)[j] = kuz_pi_inv[((uint8_t *) &x)[j]];	
	x ^= *((__m128i *) &key->k[0]);

	*((__m128i *) blk) = x;
}

// initalize lookup tables

void kuz_init()
{
	int i, j;
	w128_t x;

	for (i = 0; i < 16; i++) {
		for (j = 0; j < 256; j++) {
			x.q[0] = 0;
			x.q[1] = 0;
			x.b[i] = kuz_pi[j];
			kuz_l(&x);
			kuz_pil_enc128[i][j] = *((__m128i *) &x);
			
			x.q[0] = 0;
			x.q[1] = 0;
			x.b[i] = j; // kuz_pi[j];
			kuz_l_inv(&x);
			kuz_l_dec128[i][j] = *((__m128i *) &x);			

			x.q[0] = 0;
			x.q[1] = 0;
			x.b[i] = kuz_pi_inv[j];
			kuz_l_inv(&x);
			kuz_pil_dec128[i][j] = *((__m128i *) &x);			
		}
	}
	kuz_initialized = 1;
}


/*********************** TEST FUNCTION DEFINITIONS ***********************/
#ifdef TEST_FUNCTIONS_ENABLED

void exec_kuznechik_test(void) {
	// These are here in Big Endian format, as that seems to be the favored
	// way of representing things. However, it is open if we will have to
	// flip byte order for the final version or not.
	
	const uint8_t testvec_key[32] = {
		0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF, 
		0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 
		0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10, 
		0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF	
	};
	const uint8_t testvec_pt[16] = {
		0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x00, 
		0xFF, 0xEE, 0xDD, 0xCC, 0xBB, 0xAA, 0x99, 0x88
	};
	const uint8_t testvec_ct[16] = { 
		0x7F, 0x67, 0x9D, 0x90, 0xBE, 0xBC, 0x24, 0x30, 
		0x5A, 0x46, 0x8D, 0x42, 0xB9, 0xD4, 0xED, 0xCD
	};
	
	int i;
	kuz_key_t key;
	w128_t x;

	printf("Self-test:\n");
	kuz_init();
			
	kuz_set_encrypt_key(&key, testvec_key);	
	for (i = 0; i < 10; i++) {	
		printf("K_%d\t=", i + 1);
		print_w128(&key.k[i]);
	}

	for (i = 0; i < 16; i++)
		x.b[i] = testvec_pt[i];
	printf("PT\t=");
	print_w128(&x);

	kuz_encrypt_block(&key, &x);

	printf("CT\t=");
	print_w128(&x);

	for (i = 0; i < 16; i++) {
		if (testvec_ct[i] != x.b[i]) {
			fprintf(stderr, "Encryption self-test failure.\n");
			// return -1;
		}
	}

	kuz_set_decrypt_key(&key, testvec_key);
	kuz_decrypt_block(&key, &x);

	printf("PT\t=");
	print_w128(&x);
	
	for (i = 0; i < 16; i++) {
		if (testvec_pt[i] != x.b[i]) {
			fprintf(stderr, "Decryption self-test failure.\n");
			// return -2;
		}
	}
	
	printf("Self-test OK!\n");
	
};
#endif