/**
 *  FIPS-180-2 compliant SHA-256 implementation
 *
 *  Copyright (C) 2001-2003  Christophe Devine
 *
 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "precompiled.h" 

#include "sha.h"

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

#define GET_UINT32(n,b,i)				\
{										\
	(n) = ( (uint) (b)[(i)  ] << 24 )	\
		| ( (uint) (b)[(i) + 1] << 16 )	\
		| ( (uint) (b)[(i) + 2] <<  8 )	\
		| ( (uint) (b)[(i) + 3]    );	\
}
 
#define PUT_UINT32(n,b,i)							\
{													\
	(b)[(i) ] = (byte) ( ((n) >> 24) & 0xFF );		\
	(b)[(i) + 1] = (byte) ( ((n) >> 16) & 0xFF );	\
	(b)[(i) + 2] = (byte) ( ((n) >>  8) & 0xFF );	\
	(b)[(i) + 3] = (byte) ( ((n)      ) & 0xFF  );	\
}
 
SHA256::SHA256()
{
	init();
}
void SHA256::init()
{
	total[0] = 0;
	total[1] = 0;
 
	state[0] = 0x6A09E667;
	state[1] = 0xBB67AE85;
	state[2] = 0x3C6EF372;
	state[3] = 0xA54FF53A;
	state[4] = 0x510E527F;
	state[5] = 0x9B05688C;
	state[6] = 0x1F83D9AB;
	state[7] = 0x5BE0CD19;
}
 
void SHA256::transform(byte (&data)[64])
{
	uint temp1, temp2, W[64];
	uint A, B, C, D, E, F, G, H;
 
	GET_UINT32( W[0],  data,  0 );
	GET_UINT32( W[1],  data,  4 );
	GET_UINT32( W[2],  data,  8 );
	GET_UINT32( W[3],  data, 12 );
	GET_UINT32( W[4],  data, 16 );
	GET_UINT32( W[5],  data, 20 );
	GET_UINT32( W[6],  data, 24 );
	GET_UINT32( W[7],  data, 28 );
	GET_UINT32( W[8],  data, 32 );
	GET_UINT32( W[9],  data, 36 );
	GET_UINT32( W[10], data, 40 );
	GET_UINT32( W[11], data, 44 );
	GET_UINT32( W[12], data, 48 );
	GET_UINT32( W[13], data, 52 );
	GET_UINT32( W[14], data, 56 );
	GET_UINT32( 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 = state[0];
	B = state[1];
	C = state[2];
	D = state[3];
	E = state[4];
	F = state[5];
	G = state[6];
	H = 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 );
 
	state[0] += A;
	state[1] += B;
	state[2] += C;
	state[3] += D;
	state[4] += E;
	state[5] += F;
	state[6] += G;
	state[7] += H;
}
 
void SHA256::update(const void* input, uint length )
{
	uint left, fill;
 
	if( ! length ) return;
 
	left = total[0] & 0x3F;
	fill = 64 - left;
 
	total[0] += length;
	total[0] &= 0xFFFFFFFF;
 
	if( total[0] < length )
		total[1]++;
 
	if( left && length >= fill )
	{
		memcpy( (void *) (buffer + left),
				(void *) input, fill );
		transform(buffer);
		length -= fill;
		input  = (byte*)input + fill;
		left = 0;
	}
 
	while( length >= 64 )
	{
		transform((byte(&)[64])input);
		length -= 64;
		input  = (byte*)input + 64;
	}
 
	if( length )
	{
		memcpy( (void *) (buffer + left),
				(void *) input, length );
	}
}
 
static byte sha256_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
};
 
void SHA256::finish(byte (&digest)[32] )
{
	uint last, padn;
	uint high, low;
	byte msglen[8];
 
	high = ( total[0] >> 29 )
		 | ( total[1] <<  3 );
	low  = ( total[0] <<  3 );
 
	PUT_UINT32( high, msglen, 0 );
	PUT_UINT32( low,  msglen, 4 );
 
	last = total[0] & 0x3F;
	padn = ( last < 56 ) ? ( 56 - last ) : ( 120 - last );
 
	update(sha256_padding, padn);
	update(msglen, 8);
 
	PUT_UINT32( state[0], digest,  0 );
	PUT_UINT32( state[1], digest,  4 );
	PUT_UINT32( state[2], digest,  8 );
	PUT_UINT32( state[3], digest, 12 );
	PUT_UINT32( state[4], digest, 16 );
	PUT_UINT32( state[5], digest, 20 );
	PUT_UINT32( state[6], digest, 24 );
	PUT_UINT32( state[7], digest, 28 );
}
 
 
/**
 * From BSD's PBKDF implementation:
 */
static void hmac_sha256(byte (&digest)[SHA_DIGEST_SIZE],
						const byte* text, size_t text_len, const byte* key, size_t key_len)
{
	SHA256 hash;
	byte tk[SHA_DIGEST_SIZE]; // temporary key incase we need to pad the key with zero bytes
	if (key_len > SHA_DIGEST_SIZE)
	{
		hash.update(key, key_len);
		hash.finish(tk);
		key = tk;
		key_len = SHA_DIGEST_SIZE;
	}
 
	byte k_pad[SHA_DIGEST_SIZE];
 
	memset(k_pad, 0, sizeof k_pad);
	memcpy(k_pad, key, key_len);
	for (int i = 0; i < SHA_DIGEST_SIZE; ++i)
		k_pad[i] ^= 0x36;
	hash.init();
	hash.update(k_pad, SHA_DIGEST_SIZE);
	hash.update(text, text_len);
	hash.finish(digest);
 
 
	memset(k_pad, 0, sizeof k_pad);
	memcpy(k_pad, key, key_len);
	for (int i = 0; i < SHA_DIGEST_SIZE; ++i)
		k_pad[i] ^= 0x5c;
 
	hash.init();
	hash.update(k_pad, SHA_DIGEST_SIZE);
	hash.update(digest, SHA_DIGEST_SIZE);
	hash.finish(digest);
}
 
 
int pbkdf2(byte (&output)[SHA_DIGEST_SIZE],
			const byte* key, size_t key_len,
			const byte* salt, size_t salt_len,
			unsigned rounds)
{
	byte asalt[SHA_DIGEST_SIZE + 4], obuf[SHA_DIGEST_SIZE], d1[SHA_DIGEST_SIZE], d2[SHA_DIGEST_SIZE];
 
	if (rounds < 1 || key_len == 0 || salt_len == 0)
		return -1;
 
	if (salt_len > SHA_DIGEST_SIZE) salt_len = SHA_DIGEST_SIZE; // length cap for the salt
	memset(asalt, 0, salt_len);
	memcpy(asalt, salt, salt_len);
 
	for (unsigned count = 1; ; ++count)
	{
		asalt[salt_len + 0] = (count >> 24) & 0xff;
		asalt[salt_len + 1] = (count >> 16) & 0xff;
		asalt[salt_len + 2] = (count >> 8) & 0xff;
		asalt[salt_len + 3] = count & 0xff;
		hmac_sha256(d1, asalt, salt_len + 4, key, key_len);
		memcpy(obuf, d1, SHA_DIGEST_SIZE);
 
		for (unsigned i = 1; i < rounds; i++)
		{
			hmac_sha256(d2, d1, SHA_DIGEST_SIZE, key, key_len);
			memcpy(d1, d2, SHA_DIGEST_SIZE);
			for (unsigned j = 0; j < SHA_DIGEST_SIZE; j++)
				obuf[j] ^= d1[j];
		}
 
		memcpy(output, obuf, SHA_DIGEST_SIZE);
		key += SHA_DIGEST_SIZE;
		if (key_len < SHA_DIGEST_SIZE)
			break;
		key_len -= SHA_DIGEST_SIZE;
	};
	return 0;
}