/*-
 * Copyright 2009 Colin Percival, 2011 ArtForz, 2011 pooler, 2013 Balthazar
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 * This file was originally written by Colin Percival as part of the Tarsnap
 * online backup system.
 */

#include <stdlib.h>
#include <stdint.h>

#include "scrypt.h"
#include "pbkdf2.h"

#include "util.h"
#include "net.h"

#define SCRYPT_BUFFER_SIZE (131072 + 63)

#if defined (__x86_64__) || defined (__i386__) || defined(__arm__)
extern "C" void scrypt_core(uint32_t *X, uint32_t *V);
#else
// TODO: Add cross-platform scrypt_core implementation
#endif

/* cpu and memory intensive function to transform a 80 byte buffer into a 32 byte output
   scratchpad size needs to be at least 63 + (128 * r * p) + (256 * r + 64) + (128 * r * N) bytes
   r = 1, p = 1, N = 1024
 */

uint256 scrypt_nosalt(const void* input, size_t inputlen, void *scratchpad)
{
    uint32_t *V;
    uint32_t X[32];
    uint256 result = 0;
    V = (uint32_t *)(((uintptr_t)(scratchpad) + 63) & ~ (uintptr_t)(63));

    PBKDF2_SHA256((const uint8_t*)input, inputlen, (const uint8_t*)input, inputlen, 1, (uint8_t *)X, 128);
    scrypt_core(X, V);
    PBKDF2_SHA256((const uint8_t*)input, inputlen, (uint8_t *)X, 128, 1, (uint8_t*)&result, 32);

    return result;
}

uint256 scrypt(const void* data, size_t datalen, const void* salt, size_t saltlen, void *scratchpad)
{
    uint32_t *V;
    uint32_t X[32];
    uint256 result = 0;
    V = (uint32_t *)(((uintptr_t)(scratchpad) + 63) & ~ (uintptr_t)(63));

    PBKDF2_SHA256((const uint8_t*)data, datalen, (const uint8_t*)salt, saltlen, 1, (uint8_t *)X, 128);
    scrypt_core(X, V);
    PBKDF2_SHA256((const uint8_t*)data, datalen, (uint8_t *)X, 128, 1, (uint8_t*)&result, 32);

    return result;
}

uint256 scrypt_hash(const void* input, size_t inputlen)
{
    unsigned char scratchpad[SCRYPT_BUFFER_SIZE];
    return scrypt_nosalt(input, inputlen, scratchpad);
}

uint256 scrypt_salted_hash(const void* input, size_t inputlen, const void* salt, size_t saltlen)
{
    unsigned char scratchpad[SCRYPT_BUFFER_SIZE];
    return scrypt(input, inputlen, salt, saltlen, scratchpad);
}

uint256 scrypt_salted_multiround_hash(const void* input, size_t inputlen, const void* salt, size_t saltlen, const unsigned int nRounds)
{
    uint256 resultHash = scrypt_salted_hash(input, inputlen, salt, saltlen);
    uint256 transitionalHash = resultHash;

    for(unsigned int i = 1; i < nRounds; i++)
    {
        resultHash = scrypt_salted_hash(input, inputlen, (const void*)&transitionalHash, 32);
        transitionalHash = resultHash;
    }

    return resultHash;
}

uint256 scrypt_blockhash(const void* input)
{
    unsigned char scratchpad[SCRYPT_BUFFER_SIZE];
    return scrypt_nosalt(input, 80, scratchpad);
}