/* scrypt.c - Scrypt password-based key derivation function.
* Copyright (C) 2012 Simon Josefsson
* Copyright (C) 2013 Christian Grothoff
* Copyright (C) 2013 g10 Code GmbH
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser general Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
/* Adapted from the nettle, low-level cryptographics library for
* libgcrypt by Christian Grothoff; original license:
*
* Copyright (C) 2012 Simon Josefsson
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02111-1301, USA.
*/
#include <config.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "g10lib.h"
#include "kdf-internal.h"
#include "bufhelp.h"
/* We really need a 64 bit type for this code. */
#define SALSA20_INPUT_LENGTH 16
#define ROTL32(n,x) (((x)<<(n)) | ((x)>>(32-(n))))
/* Reads a 64-bit integer, in network, big-endian, byte order */
#define READ_UINT64(p) buf_get_be64(p)
/* And the other, little-endian, byteorder */
#define LE_READ_UINT64(p) buf_get_le64(p)
#define LE_SWAP32(v) le_bswap32(v)
#define QROUND(x0, x1, x2, x3) do { \
x1 ^= ROTL32(7, x0 + x3); \
x2 ^= ROTL32(9, x1 + x0); \
x3 ^= ROTL32(13, x2 + x1); \
x0 ^= ROTL32(18, x3 + x2); \
} while(0)
static void
salsa20_core (u32 *dst, const u32 *src, unsigned int rounds)
{
u32 x[SALSA20_INPUT_LENGTH];
unsigned i;
assert ( (rounds & 1) == 0);
for (i = 0; i < SALSA20_INPUT_LENGTH; i++)
x[i] = LE_SWAP32(src[i]);
for (i = 0; i < rounds;i += 2)
{
QROUND(x[0], x[4], x[8], x[12]);
QROUND(x[5], x[9], x[13], x[1]);
QROUND(x[10], x[14], x[2], x[6]);
QROUND(x[15], x[3], x[7], x[11]);
QROUND(x[0], x[1], x[2], x[3]);
QROUND(x[5], x[6], x[7], x[4]);
QROUND(x[10], x[11], x[8], x[9]);
QROUND(x[15], x[12], x[13], x[14]);
}
for (i = 0; i < SALSA20_INPUT_LENGTH; i++)
{
u32 t = x[i] + LE_SWAP32(src[i]);
dst[i] = LE_SWAP32(t);
}
}
static void
scrypt_block_mix (u32 r, unsigned char *B, unsigned char *tmp2)
{
u64 i;
unsigned char *X = tmp2;
unsigned char *Y = tmp2 + 64;
#if 0
if (r == 1)
{
for (i = 0; i < 2 * r; i++)
{
size_t j;
printf ("B[%d] = ", (int)i);
for (j = 0; j < 64; j++)
{
if (j && !(j % 16))
printf ("\n ");
printf (" %02x", B[i * 64 + j]);
}
putchar ('\n');
}
}
#endif
/* X = B[2 * r - 1] */
memcpy (X, &B[(2 * r - 1) * 64], 64);
/* for i = 0 to 2 * r - 1 do */
for (i = 0; i <= 2 * r - 1; i++)
{
/* T = X xor B[i] */
buf_xor(X, X, &B[i * 64], 64);
/* X = Salsa (T) */
salsa20_core ((u32*)(void*)X, (u32*)(void*)X, 8);
/* Y[i] = X */
memcpy (&Y[i * 64], X, 64);
}
for (i = 0; i < r; i++)
{
memcpy (&B[i * 64], &Y[2 * i * 64], 64);
memcpy (&B[(r + i) * 64], &Y[(2 * i + 1) * 64], 64);
}
#if 0
if (r==1)
{
for (i = 0; i < 2 * r; i++)
{
size_t j;
printf ("B'[%d] =", (int)i);
for (j = 0; j < 64; j++)
{
if (j && !(j % 16))
printf ("\n ");
printf (" %02x", B[i * 64 + j]);
}
putchar ('\n');
}
}
#endif
}
static void
scrypt_ro_mix (u32 r, unsigned char *B, u64 N,
unsigned char *tmp1, unsigned char *tmp2)
{
unsigned char *X = B, *T = B;
u64 i;
#if 0
if (r == 1)
{
printf ("B = ");
for (i = 0; i < 128 * r; i++)
{
if (i && !(i % 16))
printf ("\n ");
printf (" %02x", B[i]);
}
putchar ('\n');
}
#endif
/* for i = 0 to N - 1 do */
for (i = 0; i <= N - 1; i++)
{
/* V[i] = X */
memcpy (&tmp1[i * 128 * r], X, 128 * r);
/* X = ScryptBlockMix (X) */
scrypt_block_mix (r, X, tmp2);
}
/* for i = 0 to N - 1 do */
for (i = 0; i <= N - 1; i++)
{
u64 j;
/* j = Integerify (X) mod N */
j = LE_READ_UINT64 (&X[128 * r - 64]) % N;
/* T = X xor V[j] */
buf_xor (T, T, &tmp1[j * 128 * r], 128 * r);
/* X = scryptBlockMix (T) */
scrypt_block_mix (r, T, tmp2);
}
#if 0
if (r == 1)
{
printf ("B' =");
for (i = 0; i < 128 * r; i++)
{
if (i && !(i % 16))
printf ("\n ");
printf (" %02x", B[i]);
}
putchar ('\n');
}
#endif
}
/*
*
*/
gcry_err_code_t
_gcry_kdf_scrypt (const unsigned char *passwd, size_t passwdlen,
int algo, int subalgo,
const unsigned char *salt, size_t saltlen,
unsigned long iterations,
size_t dkLen, unsigned char *DK)
{
u64 N = subalgo; /* CPU/memory cost parameter. */
u32 r; /* Block size. */
u32 p = iterations; /* Parallelization parameter. */
gpg_err_code_t ec;
u32 i;
unsigned char *B = NULL;
unsigned char *tmp1 = NULL;
unsigned char *tmp2 = NULL;
size_t r128;
size_t nbytes;
if (subalgo < 1 || !iterations)
return GPG_ERR_INV_VALUE;
if (algo == GCRY_KDF_SCRYPT)
r = 8;
else if (algo == 41) /* Hack to allow the use of all test vectors. */
r = 1;
else
return GPG_ERR_UNKNOWN_ALGORITHM;
r128 = r * 128;
if (r128 / 128 != r)
return GPG_ERR_ENOMEM;
nbytes = p * r128;
if (r128 && nbytes / r128 != p)
return GPG_ERR_ENOMEM;
nbytes = N * r128;
if (r128 && nbytes / r128 != N)
return GPG_ERR_ENOMEM;
nbytes = 64 + r128;
if (nbytes < r128)
return GPG_ERR_ENOMEM;
B = xtrymalloc (p * r128);
if (!B)
{
ec = gpg_err_code_from_syserror ();
goto leave;
}
tmp1 = xtrymalloc (N * r128);
if (!tmp1)
{
ec = gpg_err_code_from_syserror ();
goto leave;
}
tmp2 = xtrymalloc (64 + r128);
if (!tmp2)
{
ec = gpg_err_code_from_syserror ();
goto leave;
}
ec = _gcry_kdf_pkdf2 (passwd, passwdlen, GCRY_MD_SHA256, salt, saltlen,
1 /* iterations */, p * r128, B);
for (i = 0; !ec && i < p; i++)
scrypt_ro_mix (r, &B[i * r128], N, tmp1, tmp2);
for (i = 0; !ec && i < p; i++)
ec = _gcry_kdf_pkdf2 (passwd, passwdlen, GCRY_MD_SHA256, B, p * r128,
1 /* iterations */, dkLen, DK);
leave:
xfree (tmp2);
xfree (tmp1);
xfree (B);
return ec;
}
