/*
 *	FIPS-180-2 compliant SHA-256 implementation
 *
 *  Based on TropicSSL: Copyright (C) 2017 Shanghai Real-Thread Technology Co., Ltd
 * 
 *	Based on XySSL: Copyright (C) 2006-2008	 Christophe Devine
 *
 *	Copyright (C) 2009	Paul Bakker <polarssl_maintainer at polarssl dot org>
 *
 *	All rights reserved.
 *
 *	Redistribution and use in source and binary forms, with or without
 *	modification, are permitted provided that the following conditions
 *	are met:
 *
 *	  * Redistributions of source code must retain the above copyright
 *		notice, this list of conditions and the following disclaimer.
 *	  * 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.
 *	  * Neither the names of PolarSSL or XySSL nor the names of its contributors
 *		may be used to endorse or promote products derived from this software
 *		without specific prior written permission.
 *
 *	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *	"AS IS" AND ANY EXPRESS 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 COPYRIGHT
 *	OWNER OR 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.
 */
/*
 *	The SHA-256 Secure Hash Standard was published by NIST in 2002.
 *
 *	http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
 */

#include "tinycrypt_config.h"

#if defined(TINY_CRYPT_SHA256)

#include "tinycrypt.h"

#include <string.h>
#include <stdio.h>

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_ULONG_BE
#define GET_ULONG_BE(n,b,i)								\
	{													\
		(n) = ( (unsigned long) (b)[(i)	   ] << 24 )	\
			| ( (unsigned long) (b)[(i) + 1] << 16 )	\
			| ( (unsigned long) (b)[(i) + 2] <<	 8 )	\
			| ( (unsigned long) (b)[(i) + 3]	   );	\
	}
#endif

#ifndef PUT_ULONG_BE
#define PUT_ULONG_BE(n,b,i)								\
	{													\
		(b)[(i)	   ] = (unsigned char) ( (n) >> 24 );	\
		(b)[(i) + 1] = (unsigned char) ( (n) >> 16 );	\
		(b)[(i) + 2] = (unsigned char) ( (n) >>	 8 );	\
		(b)[(i) + 3] = (unsigned char) ( (n)	   );	\
	}
#endif

/*
 * SHA-256 context setup
 */
void tiny_sha2_starts(tiny_sha2_context * ctx, int is224)
{
	ctx->total[0] = 0;
	ctx->total[1] = 0;

	if (is224 == 0) {
		/* SHA-256 */
		ctx->state[0] = 0x6A09E667;
		ctx->state[1] = 0xBB67AE85;
		ctx->state[2] = 0x3C6EF372;
		ctx->state[3] = 0xA54FF53A;
		ctx->state[4] = 0x510E527F;
		ctx->state[5] = 0x9B05688C;
		ctx->state[6] = 0x1F83D9AB;
		ctx->state[7] = 0x5BE0CD19;
	} else {
		/* SHA-224 */
		ctx->state[0] = 0xC1059ED8;
		ctx->state[1] = 0x367CD507;
		ctx->state[2] = 0x3070DD17;
		ctx->state[3] = 0xF70E5939;
		ctx->state[4] = 0xFFC00B31;
		ctx->state[5] = 0x68581511;
		ctx->state[6] = 0x64F98FA7;
		ctx->state[7] = 0xBEFA4FA4;
	}

	ctx->is224 = is224;
}

static void sha2_process(tiny_sha2_context * ctx, unsigned char data[64])
{
	unsigned long temp1, temp2, W[64];
	unsigned long A, B, C, D, E, F, G, H;

	GET_ULONG_BE(W[0], data, 0);
	GET_ULONG_BE(W[1], data, 4);
	GET_ULONG_BE(W[2], data, 8);
	GET_ULONG_BE(W[3], data, 12);
	GET_ULONG_BE(W[4], data, 16);
	GET_ULONG_BE(W[5], data, 20);
	GET_ULONG_BE(W[6], data, 24);
	GET_ULONG_BE(W[7], data, 28);
	GET_ULONG_BE(W[8], data, 32);
	GET_ULONG_BE(W[9], data, 36);
	GET_ULONG_BE(W[10], data, 40);
	GET_ULONG_BE(W[11], data, 44);
	GET_ULONG_BE(W[12], data, 48);
	GET_ULONG_BE(W[13], data, 52);
	GET_ULONG_BE(W[14], data, 56);
	GET_ULONG_BE(W[15], data, 60);

#define	 SHR(x,n) ((x & 0xFFFFFFFF) >> n)
#define ROTR(x,n) (SHR(x,n) | (x << (32 - n)))

#define S0(x) (ROTR(x, 7) ^ ROTR(x,18) ^  SHR(x, 3))
#define S1(x) (ROTR(x,17) ^ ROTR(x,19) ^  SHR(x,10))

#define S2(x) (ROTR(x, 2) ^ ROTR(x,13) ^ ROTR(x,22))
#define S3(x) (ROTR(x, 6) ^ ROTR(x,11) ^ ROTR(x,25))

#define F0(x,y,z) ((x & y) | (z & (x | y)))
#define F1(x,y,z) (z ^ (x & (y ^ z)))

#define R(t)									\
	(											\
		W[t] = S1(W[t -	 2]) + W[t -  7] +		\
		S0(W[t - 15]) + W[t - 16]				\
		)

#define P(a,b,c,d,e,f,g,h,x,K)					\
	{											\
		temp1 = h + S3(e) + F1(e,f,g) + K + x;	\
		temp2 = S2(a) + F0(a,b,c);				\
		d += temp1; h = temp1 + temp2;			\
	}

	A = ctx->state[0];
	B = ctx->state[1];
	C = ctx->state[2];
	D = ctx->state[3];
	E = ctx->state[4];
	F = ctx->state[5];
	G = ctx->state[6];
	H = ctx->state[7];

	P(A, B, C, D, E, F, G, H, W[0], 0x428A2F98);
	P(H, A, B, C, D, E, F, G, W[1], 0x71374491);
	P(G, H, A, B, C, D, E, F, W[2], 0xB5C0FBCF);
	P(F, G, H, A, B, C, D, E, W[3], 0xE9B5DBA5);
	P(E, F, G, H, A, B, C, D, W[4], 0x3956C25B);
	P(D, E, F, G, H, A, B, C, W[5], 0x59F111F1);
	P(C, D, E, F, G, H, A, B, W[6], 0x923F82A4);
	P(B, C, D, E, F, G, H, A, W[7], 0xAB1C5ED5);
	P(A, B, C, D, E, F, G, H, W[8], 0xD807AA98);
	P(H, A, B, C, D, E, F, G, W[9], 0x12835B01);
	P(G, H, A, B, C, D, E, F, W[10], 0x243185BE);
	P(F, G, H, A, B, C, D, E, W[11], 0x550C7DC3);
	P(E, F, G, H, A, B, C, D, W[12], 0x72BE5D74);
	P(D, E, F, G, H, A, B, C, W[13], 0x80DEB1FE);
	P(C, D, E, F, G, H, A, B, W[14], 0x9BDC06A7);
	P(B, C, D, E, F, G, H, A, W[15], 0xC19BF174);
	P(A, B, C, D, E, F, G, H, R(16), 0xE49B69C1);
	P(H, A, B, C, D, E, F, G, R(17), 0xEFBE4786);
	P(G, H, A, B, C, D, E, F, R(18), 0x0FC19DC6);
	P(F, G, H, A, B, C, D, E, R(19), 0x240CA1CC);
	P(E, F, G, H, A, B, C, D, R(20), 0x2DE92C6F);
	P(D, E, F, G, H, A, B, C, R(21), 0x4A7484AA);
	P(C, D, E, F, G, H, A, B, R(22), 0x5CB0A9DC);
	P(B, C, D, E, F, G, H, A, R(23), 0x76F988DA);
	P(A, B, C, D, E, F, G, H, R(24), 0x983E5152);
	P(H, A, B, C, D, E, F, G, R(25), 0xA831C66D);
	P(G, H, A, B, C, D, E, F, R(26), 0xB00327C8);
	P(F, G, H, A, B, C, D, E, R(27), 0xBF597FC7);
	P(E, F, G, H, A, B, C, D, R(28), 0xC6E00BF3);
	P(D, E, F, G, H, A, B, C, R(29), 0xD5A79147);
	P(C, D, E, F, G, H, A, B, R(30), 0x06CA6351);
	P(B, C, D, E, F, G, H, A, R(31), 0x14292967);
	P(A, B, C, D, E, F, G, H, R(32), 0x27B70A85);
	P(H, A, B, C, D, E, F, G, R(33), 0x2E1B2138);
	P(G, H, A, B, C, D, E, F, R(34), 0x4D2C6DFC);
	P(F, G, H, A, B, C, D, E, R(35), 0x53380D13);
	P(E, F, G, H, A, B, C, D, R(36), 0x650A7354);
	P(D, E, F, G, H, A, B, C, R(37), 0x766A0ABB);
	P(C, D, E, F, G, H, A, B, R(38), 0x81C2C92E);
	P(B, C, D, E, F, G, H, A, R(39), 0x92722C85);
	P(A, B, C, D, E, F, G, H, R(40), 0xA2BFE8A1);
	P(H, A, B, C, D, E, F, G, R(41), 0xA81A664B);
	P(G, H, A, B, C, D, E, F, R(42), 0xC24B8B70);
	P(F, G, H, A, B, C, D, E, R(43), 0xC76C51A3);
	P(E, F, G, H, A, B, C, D, R(44), 0xD192E819);
	P(D, E, F, G, H, A, B, C, R(45), 0xD6990624);
	P(C, D, E, F, G, H, A, B, R(46), 0xF40E3585);
	P(B, C, D, E, F, G, H, A, R(47), 0x106AA070);
	P(A, B, C, D, E, F, G, H, R(48), 0x19A4C116);
	P(H, A, B, C, D, E, F, G, R(49), 0x1E376C08);
	P(G, H, A, B, C, D, E, F, R(50), 0x2748774C);
	P(F, G, H, A, B, C, D, E, R(51), 0x34B0BCB5);
	P(E, F, G, H, A, B, C, D, R(52), 0x391C0CB3);
	P(D, E, F, G, H, A, B, C, R(53), 0x4ED8AA4A);
	P(C, D, E, F, G, H, A, B, R(54), 0x5B9CCA4F);
	P(B, C, D, E, F, G, H, A, R(55), 0x682E6FF3);
	P(A, B, C, D, E, F, G, H, R(56), 0x748F82EE);
	P(H, A, B, C, D, E, F, G, R(57), 0x78A5636F);
	P(G, H, A, B, C, D, E, F, R(58), 0x84C87814);
	P(F, G, H, A, B, C, D, E, R(59), 0x8CC70208);
	P(E, F, G, H, A, B, C, D, R(60), 0x90BEFFFA);
	P(D, E, F, G, H, A, B, C, R(61), 0xA4506CEB);
	P(C, D, E, F, G, H, A, B, R(62), 0xBEF9A3F7);
	P(B, C, D, E, F, G, H, A, R(63), 0xC67178F2);

	ctx->state[0] += A;
	ctx->state[1] += B;
	ctx->state[2] += C;
	ctx->state[3] += D;
	ctx->state[4] += E;
	ctx->state[5] += F;
	ctx->state[6] += G;
	ctx->state[7] += H;
}

/*
 * SHA-256 process buffer
 */
void tiny_sha2_update(tiny_sha2_context * ctx, unsigned char *input, int ilen)
{
	int fill;
	unsigned long left;

	if (ilen <= 0)
		return;

	left = ctx->total[0] & 0x3F;
	fill = 64 - left;

	ctx->total[0] += ilen;
	ctx->total[0] &= 0xFFFFFFFF;

	if (ctx->total[0] < (unsigned long)ilen)
		ctx->total[1]++;

	if (left && ilen >= fill) {
		memcpy((void *)(ctx->buffer + left), (void *)input, fill);
		sha2_process(ctx, ctx->buffer);
		input += fill;
		ilen -= fill;
		left = 0;
	}

	while (ilen >= 64) {
		sha2_process(ctx, input);
		input += 64;
		ilen -= 64;
	}

	if (ilen > 0) {
		memcpy((void *)(ctx->buffer + left), (void *)input, ilen);
	}
}

static const unsigned char sha2_padding[64] = {
	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/*
 * SHA-256 final digest
 */
void tiny_sha2_finish(tiny_sha2_context * ctx, unsigned char output[32])
{
	unsigned long last, padn;
	unsigned long high, low;
	unsigned char msglen[8];

	high = (ctx->total[0] >> 29)
	    | (ctx->total[1] << 3);
	low = (ctx->total[0] << 3);

	PUT_ULONG_BE(high, msglen, 0);
	PUT_ULONG_BE(low, msglen, 4);

	last = ctx->total[0] & 0x3F;
	padn = (last < 56) ? (56 - last) : (120 - last);

	tiny_sha2_update(ctx, (unsigned char *)sha2_padding, padn);
	tiny_sha2_update(ctx, msglen, 8);

	PUT_ULONG_BE(ctx->state[0], output, 0);
	PUT_ULONG_BE(ctx->state[1], output, 4);
	PUT_ULONG_BE(ctx->state[2], output, 8);
	PUT_ULONG_BE(ctx->state[3], output, 12);
	PUT_ULONG_BE(ctx->state[4], output, 16);
	PUT_ULONG_BE(ctx->state[5], output, 20);
	PUT_ULONG_BE(ctx->state[6], output, 24);

	if (ctx->is224 == 0)
		PUT_ULONG_BE(ctx->state[7], output, 28);
}

/*
 * output = SHA-256( input buffer )
 */
void tiny_sha2(unsigned char *input, int ilen, unsigned char output[32], int is224)
{
	tiny_sha2_context ctx;

	tiny_sha2_starts(&ctx, is224);
	tiny_sha2_update(&ctx, input, ilen);
	tiny_sha2_finish(&ctx, output);

	memset(&ctx, 0, sizeof(tiny_sha2_context));
}

/*
 * SHA-256 HMAC context setup
 */
void tiny_sha2_hmac_starts(tiny_sha2_context * ctx, unsigned char *key, int keylen,
		      int is224)
{
	int i;
	unsigned char sum[32];

	if (keylen > 64) {
		tiny_sha2(key, keylen, sum, is224);
		keylen = (is224) ? 28 : 32;
		key = sum;
	}

	memset(ctx->ipad, 0x36, 64);
	memset(ctx->opad, 0x5C, 64);

	for (i = 0; i < keylen; i++) {
		ctx->ipad[i] = (unsigned char)(ctx->ipad[i] ^ key[i]);
		ctx->opad[i] = (unsigned char)(ctx->opad[i] ^ key[i]);
	}

	tiny_sha2_starts(ctx, is224);
	tiny_sha2_update(ctx, ctx->ipad, 64);

	memset(sum, 0, sizeof(sum));
}

/*
 * SHA-256 HMAC process buffer
 */
void tiny_sha2_hmac_update(tiny_sha2_context * ctx, unsigned char *input, int ilen)
{
	tiny_sha2_update(ctx, input, ilen);
}

/*
 * SHA-256 HMAC final digest
 */
void tiny_sha2_hmac_finish(tiny_sha2_context * ctx, unsigned char output[32])
{
	int is224, hlen;
	unsigned char tmpbuf[32];

	is224 = ctx->is224;
	hlen = (is224 == 0) ? 32 : 28;

	tiny_sha2_finish(ctx, tmpbuf);
	tiny_sha2_starts(ctx, is224);
	tiny_sha2_update(ctx, ctx->opad, 64);
	tiny_sha2_update(ctx, tmpbuf, hlen);
	tiny_sha2_finish(ctx, output);

	memset(tmpbuf, 0, sizeof(tmpbuf));
}

/*
 * output = HMAC-SHA-256( hmac key, input buffer )
 */
void tiny_sha2_hmac(unsigned char *key, int keylen,
	       unsigned char *input, int ilen,
	       unsigned char output[32], int is224)
{
	tiny_sha2_context ctx;

	tiny_sha2_hmac_starts(&ctx, key, keylen, is224);
	tiny_sha2_hmac_update(&ctx, input, ilen);
	tiny_sha2_hmac_finish(&ctx, output);

	memset(&ctx, 0, sizeof(tiny_sha2_context));
}

#endif