/*-
 * Copyright 2009 Colin Percival
 * 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 <sys/types.h>
#include <sys/mman.h>

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

#include "pbkdf2.h"

#include "crypto_scrypt_smix.h"

#include "crypto_scrypt.h"

/**
 * crypto_scrypt(passwd, passwdlen, salt, saltlen, N, r, p, buf, buflen):
 * Compute scrypt(passwd[0 .. passwdlen - 1], salt[0 .. saltlen - 1], N, r,
 * p, buflen) and write the result into buf.  The parameters r, p, and buflen
 * must satisfy r * p < 2^30 and buflen <= (2^32 - 1) * 32.  The parameter N
 * must be a power of 2 greater than 1.
 *
 * Return 0 on success; or -1 on error.
 */
int
crypto_scrypt(const uint8_t * passwd, size_t passwdlen,
    const uint8_t * salt, size_t saltlen, uint64_t N, uint32_t _r, uint32_t _p,
    uint8_t * buf, size_t buflen)
{
        void * B0, * V0, * XY0;
        uint8_t * B;
        uint32_t * V;
        uint32_t * XY;
        size_t r = _r, p = _p;
        uint32_t i;

        /* Sanity-check parameters. */
#if SIZE_MAX > UINT32_MAX
        if (buflen > (((uint64_t)(1) << 32) - 1) * 32) {
                errno = EFBIG;
                goto err0;
        }
#endif
        if ((uint64_t)(r) * (uint64_t)(p) >= (1 << 30)) {
                errno = EFBIG;
                goto err0;
        }
        if (((N & (N - 1)) != 0) || (N < 2)) {
                errno = EINVAL;
                goto err0;
        }
        if ((r > SIZE_MAX / 128 / p) ||
#if SIZE_MAX / 256 <= UINT32_MAX
            (r > (SIZE_MAX - 64) / 256) ||
#endif
            (N > SIZE_MAX / 128 / r)) {
                errno = ENOMEM;
                goto err0;
        }

        /* Allocate memory. */
#ifdef HAVE_POSIX_MEMALIGN
        if ((errno = posix_memalign(&B0, 64, 128 * r * p)) != 0)
                goto err0;
        B = (uint8_t *)(B0);
        if ((errno = posix_memalign(&XY0, 64, 256 * r + 64)) != 0)
                goto err1;
        XY = (uint32_t *)(XY0);
#if !defined(MAP_ANON) || !defined(HAVE_MMAP)
        if ((errno = posix_memalign(&V0, 64, 128 * r * N)) != 0)
                goto err2;
        V = (uint32_t *)(V0);
#endif
#else
        if ((B0 = malloc(128 * r * p + 63)) == NULL)
                goto err0;
        B = (uint8_t *)(((uintptr_t)(B0) + 63) & ~ (uintptr_t)(63));
        if ((XY0 = malloc(256 * r + 64 + 63)) == NULL)
                goto err1;
        XY = (uint32_t *)(((uintptr_t)(XY0) + 63) & ~ (uintptr_t)(63));
#if !defined(MAP_ANON) || !defined(HAVE_MMAP)
        if ((V0 = malloc(128 * r * N + 63)) == NULL)
                goto err2;
        V = (uint32_t *)(((uintptr_t)(V0) + 63) & ~ (uintptr_t)(63));
#endif
#endif
#if defined(MAP_ANON) && defined(HAVE_MMAP)
        if ((V0 = mmap(NULL, 128 * r * N, PROT_READ | PROT_WRITE,
#ifdef MAP_NOCORE
            MAP_ANON | MAP_PRIVATE | MAP_NOCORE,
#else
            MAP_ANON | MAP_PRIVATE,
#endif
            -1, 0)) == MAP_FAILED)
                goto err2;
        V = (uint32_t *)(V0);
#endif

        /* 1: (B_0 ... B_{p-1}) <-- PBKDF2(P, S, 1, p * MFLen) */
        PBKDF2_SHA256(passwd, passwdlen, salt, saltlen, 1, B, p * 128 * r);

        /* 2: for i = 0 to p - 1 do */
        for (i = 0; i < p; i++) {
                /* 3: B_i <-- MF(B_i, N) */
                crypto_scrypt_smix(&B[i * 128 * r], r, N, V, XY);
        }

        /* 5: DK <-- PBKDF2(P, B, 1, dkLen) */
        PBKDF2_SHA256(passwd, passwdlen, B, p * 128 * r, 1, buf, buflen);

        /* Free memory. */
#if defined(MAP_ANON) && defined(HAVE_MMAP)
        if (munmap(V0, 128 * r * N))
                goto err2;
#else
        free(V0);
#endif
        free(XY0);
        free(B0);

        /* Success! */
        return (0);

err2:
        free(XY0);
err1:
        free(B0);
err0:
        /* Failure! */
        return (-1);
}