/*
 * Copyright (c) 2015 - 2017 The GmSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the GmSSL Project.
 *    (http://gmssl.org/)"
 *
 * 4. The name "GmSSL Project" must not be used to endorse or promote
 *    products derived from this software without prior written
 *    permission. For written permission, please contact
 *    guanzhi1980@gmail.com.
 *
 * 5. Products derived from this software may not be called "GmSSL"
 *    nor may "GmSSL" appear in their names without prior written
 *    permission of the GmSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the GmSSL Project
 *    (http://gmssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE GmSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE GmSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#include <openssl/miracl.h>
#include <openssl/mirdef.h>
#include <openssl/sm2_standard.h>


/* test if the given array is all zero */
int Test_Null(unsigned char array[], int len)
{
	int i;
	i = 0;
	for (i = 0; i < len; i++)
	{
		if (array[i] !=	 0x00)
			return 0;
	}
	return 1;
}


/* sm2 encryption */
int SM2_standard_encrypt(unsigned char* randK, epoint *pubKey, unsigned char M[], int klen, unsigned char C[])
{
	big C1x, C1y, x2, y2, rand;
	epoint *C1, *kP, *S;
	int i;
	i = 0;
	unsigned char x2y2[SM2_NUMWORD * 2] = {0};
	SM3_STATE md;
	C1x = mirvar(0);
	C1y = mirvar(0);
	x2 = mirvar(0);
	y2 = mirvar(0);
	rand = mirvar(0);
	C1 = epoint_init();
	kP = epoint_init();
	S = epoint_init();

	//step2. calculate C1 = [k]G = (rGx, rGy)
	bytes_to_big(SM2_NUMWORD, randK, rand);
	ecurve_mult(rand, G, C1);	//C1 = [k]G
	epoint_get(C1, C1x, C1y);
	big_to_bytes(SM2_NUMWORD, C1x, C, 1);
	big_to_bytes(SM2_NUMWORD, C1y, C + SM2_NUMWORD, 1);

	//step3. test if S = [h]pubKey if the point at infinity
	ecurve_mult(para_h, pubKey, S);
	if (point_at_infinity(S))	//if S is point at infinity, return error;
		return ERR_INFINITY_POINT;

	//step4. calculate [k]PB = (x2, y2)
	ecurve_mult(rand, pubKey, kP);	//kP = [k]P
	epoint_get(kP, x2, y2);

	//step5. KDF(x2 || y2, klen)
	big_to_bytes(SM2_NUMWORD, x2, x2y2, 1);
	big_to_bytes(SM2_NUMWORD, y2, x2y2 + SM2_NUMWORD, 1);
	SM3_kdf(x2y2, SM2_NUMWORD * 2, klen, C + SM2_NUMWORD * 3);
	if (Test_Null(C + SM2_NUMWORD * 3, klen) != 0)
		return ERR_ARRAY_NULL;

	//step6. C2 = M^t
	for (i = 0; i < klen; i++)
	{
		C[SM2_NUMWORD * 3 + i] = M[i] ^ C[SM2_NUMWORD * 3 + i];
	}

	//step7. C3 = hash(x2, M, y2)
	SM3_init(&md);
	SM3_process(&md, x2y2, SM2_NUMWORD);
	SM3_process(&md, M, klen);
	SM3_process(&md, x2y2 + SM2_NUMWORD, SM2_NUMWORD);
	SM3_done(&md, C + SM2_NUMWORD * 2);
	return 0;
}


/* sm2 decryption */
int SM2_standard_decrypt(big dB, unsigned char C[], int Clen, unsigned char M[])
{
	SM3_STATE md;
	int i;
	i = 0;
	unsigned char x2y2[SM2_NUMWORD * 2] = {0};
	unsigned char hash[SM2_NUMWORD] = {0};
	big C1x, C1y, x2, y2;
	epoint *C1, *S, *dBC1;
	C1x = mirvar(0);
	C1y = mirvar(0);
	x2 = mirvar(0);
	y2 = mirvar(0);
	C1 = epoint_init();
	S = epoint_init();
	dBC1 = epoint_init();
	
	//step1. test if C1 fits the curve
	bytes_to_big(SM2_NUMWORD, C, C1x);
	bytes_to_big(SM2_NUMWORD, C + SM2_NUMWORD, C1y);
	epoint_set(C1x, C1y, 0, C1);
	i = Test_Point(C1);
	if (i != 0)
		return i;
	
	//step2. S = [h]C1 and test if S is the point at infinity
	ecurve_mult(para_h, C1, S);
	if (point_at_infinity(S))	// if S is point at infinity, return error;
		return ERR_INFINITY_POINT;
	
	//step3. [dB]C1 = (x2, y2)
	ecurve_mult(dB, C1, dBC1);
	epoint_get(dBC1, x2, y2);
	big_to_bytes(SM2_NUMWORD, x2, x2y2, 1);
	big_to_bytes(SM2_NUMWORD, y2, x2y2 + SM2_NUMWORD, 1);

	//step4. t = KDF(x2 || y2, klen)
	SM3_kdf(x2y2, SM2_NUMWORD * 2, Clen - SM2_NUMWORD * 3, M);
	if (Test_Null(M, Clen - SM2_NUMWORD * 3) != 0)
		return ERR_ARRAY_NULL;

	//step5. M = C2^t
	for (i = 0; i < Clen - SM2_NUMWORD * 3; i++)
		M[i] = M[i] ^ C[SM2_NUMWORD * 3 + i];

	//step6. hash(x2, m, y2)
	SM3_init(&md);
	SM3_process(&md, x2y2, SM2_NUMWORD);
	SM3_process(&md, M, Clen - SM2_NUMWORD * 3);
	SM3_process(&md, x2y2 + SM2_NUMWORD, SM2_NUMWORD);
	SM3_done(&md, hash);
	if (memcmp(hash, C + SM2_NUMWORD * 2, SM2_NUMWORD) != 0)
		return ERR_C3_MATCH;
	else
		return 0;
}


/* test whether the SM2 calculation is correct by comparing the result with the standard data */
int SM2_standard_enc_selftest()
{
	int tmp, i;
	tmp = 0;
	i = 0;
	unsigned char Cipher[115] = {0};
	unsigned char M[19] = {0};
	unsigned char kGxy[SM2_NUMWORD * 2] = {0};
	big ks, x, y;
	epoint *kG;


	//standard data
	unsigned char std_priKey[32] = {0x39, 0x45, 0x20, 0x8F, 0x7B, 0x21, 0x44, 0xB1, 0x3F, 0x36, 0xE3, 0x8A, 0xC6, 0xD3, 0x9F, 0x95,
									0x88, 0x93, 0x93, 0x69, 0x28, 0x60, 0xB5, 0x1A, 0x42, 0xFB, 0x81, 0xEF, 0x4D, 0xF7, 0xC5, 0xB8};
	unsigned char std_pubKey[64] = {0x09, 0xF9, 0xDF, 0x31, 0x1E, 0x54, 0x21, 0xA1, 0x50, 0xDD, 0x7D, 0x16, 0x1E, 0x4B, 0xC5, 0xC6,
									0x72, 0x17, 0x9F, 0xAD, 0x18, 0x33, 0xFC, 0x07, 0x6B, 0xB0, 0x8F, 0xF3, 0x56, 0xF3, 0x50, 0x20,
									0xCC, 0xEA, 0x49, 0x0C, 0xE2, 0x67, 0x75, 0xA5, 0x2D, 0xC6, 0xEA, 0x71, 0x8C, 0xC1, 0xAA, 0x60,
									0x0A, 0xED, 0x05, 0xFB, 0xF3, 0x5E, 0x08, 0x4A, 0x66, 0x32, 0xF6, 0x07, 0x2D, 0xA9, 0xAD, 0x13};
	unsigned char std_rand[32] = {0x59, 0x27, 0x6E, 0x27, 0xD5, 0x06, 0x86, 0x1A, 0x16, 0x68, 0x0F, 0x3A, 0xD9, 0xC0, 0x2D, 0xCC,
								  0xEF, 0x3C, 0xC1, 0xFA, 0x3C, 0xDB, 0xE4, 0xCE, 0x6D, 0x54, 0xB8, 0x0D, 0xEA, 0xC1, 0xBC, 0x21};
	unsigned char std_Message[19] = {0x65, 0x6E, 0x63, 0x72, 0x79, 0x70, 0x74, 0x69, 0x6F, 0x6E, 0x20, 0x73, 0x74, 0x61, 0x6E, 0x64, 
									 0x61, 0x72, 0x64};
	unsigned char std_Cipher[115] = {0x04, 0xEB, 0xFC, 0x71, 0x8E, 0x8D, 0x17, 0x98, 0x62, 0x04, 0x32, 0x26, 0x8E, 0x77, 0xFE, 0xB6,
									 0x41, 0x5E, 0x2E, 0xDE, 0x0E, 0x07, 0x3C, 0x0F, 0x4F, 0x64, 0x0E, 0xCD, 0x2E, 0x14, 0x9A, 0x73,
									 0xE8, 0x58, 0xF9, 0xD8, 0x1E, 0x54, 0x30, 0xA5, 0x7B, 0x36, 0xDA, 0xAB, 0x8F, 0x95, 0x0A, 0x3C,
									 0x64, 0xE6, 0xEE, 0x6A, 0x63, 0x09, 0x4D, 0x99, 0x28, 0x3A, 0xFF, 0x76, 0x7E, 0x12, 0x4D, 0xF0,
									 0x59, 0x98, 0x3C, 0x18, 0xF8, 0x09, 0xE2, 0x62, 0x92, 0x3C, 0x53, 0xAE, 0xC2, 0x95, 0xD3, 0x03,
									 0x83, 0xB5, 0x4E, 0x39, 0xD6, 0x09, 0xD1, 0x60, 0xAF, 0xCB, 0x19, 0x08, 0xD0, 0xBD, 0x87, 0x66,
									 0x21, 0x88, 0x6C, 0xA9, 0x89, 0xCA, 0x9C, 0x7D, 0x58, 0x08, 0x73, 0x07, 0xCA, 0x93, 0x09, 0x2D, 
									 0x65, 0x1E, 0xFA};
	mip= mirsys(1000, 16);
	mip->IOBASE = 16;
	x = mirvar(0);
	y = mirvar(0);
	ks = mirvar(0);
	kG = epoint_init();
	bytes_to_big(32, std_priKey, ks);	//ks is the standard private key

	
	//initiate SM2 curve
	SM2_standard_init();
	
	//generate key pair
	tmp = SM2_standard_keygeneration(ks, kG);
	if (tmp != 0)
		return tmp;
	epoint_get(kG, x, y);
	big_to_bytes(SM2_NUMWORD, x, kGxy, 1);
	big_to_bytes(SM2_NUMWORD, y, kGxy + SM2_NUMWORD, 1);
	if (memcmp(kGxy, std_pubKey, SM2_NUMWORD * 2) != 0)
		return ERR_SELFTEST_KG;

	//encrypt data and compare the result with the standard data
	tmp = SM2_standard_encrypt(std_rand, kG, std_Message, 19, Cipher);
	if (tmp != 0)
		return tmp;
	if (memcmp(Cipher, std_Cipher, 19 + SM2_NUMWORD * 3) != 0)
		return ERR_SELFTEST_ENC;
	
	//decrypt cipher and compare the result with the standard data
	tmp = SM2_standard_decrypt(ks, Cipher, 115, M);
	if (tmp != 0)
		return tmp;
	if (memcmp(M, std_Message, 19) != 0)
		return ERR_SELFTEST_DEC;
	return 0;
}