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/* gc-pbkdf2-sha1.c --- Password-Based Key Derivation Function a'la PKCS#5
Copyright (C) 2002, 2003, 2004, 2005, 2006, 2009 Free Software Foundation, Inc.
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, 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
/* Written by Simon Josefsson. */
/* Imported from gnulib. */
#include <grub/crypto.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/dl.h>
GRUB_MOD_LICENSE ("GPLv2+");
/* Implement PKCS#5 PBKDF2 as per RFC 2898. The PRF to use is HMAC variant
of digest supplied by MD. Inputs are the password P of length PLEN,
the salt S of length SLEN, the iteration counter C (> 0), and the
desired derived output length DKLEN. Output buffer is DK which
must have room for at least DKLEN octets. The output buffer will
be filled with the derived data. */
gcry_err_code_t
grub_crypto_pbkdf2 (const struct gcry_md_spec *md,
const grub_uint8_t *P, grub_size_t Plen,
const grub_uint8_t *S, grub_size_t Slen,
unsigned int c,
grub_uint8_t *DK, grub_size_t dkLen)
{
unsigned int hLen = md->mdlen;
grub_uint8_t U[GRUB_CRYPTO_MAX_MDLEN];
grub_uint8_t T[GRUB_CRYPTO_MAX_MDLEN];
unsigned int u;
unsigned int l;
unsigned int r;
unsigned int i;
unsigned int k;
gcry_err_code_t rc;
grub_uint8_t *tmp;
grub_size_t tmplen = Slen + 4;
if (md->mdlen > GRUB_CRYPTO_MAX_MDLEN || md->mdlen == 0)
return GPG_ERR_INV_ARG;
if (c == 0)
return GPG_ERR_INV_ARG;
if (dkLen == 0)
return GPG_ERR_INV_ARG;
if (dkLen > 4294967295U)
return GPG_ERR_INV_ARG;
l = ((dkLen - 1) / hLen) + 1;
r = dkLen - (l - 1) * hLen;
tmp = grub_malloc (tmplen);
if (tmp == NULL)
return GPG_ERR_OUT_OF_MEMORY;
grub_memcpy (tmp, S, Slen);
for (i = 1; i - 1 < l; i++)
{
grub_memset (T, 0, hLen);
for (u = 0; u < c; u++)
{
if (u == 0)
{
tmp[Slen + 0] = (i & 0xff000000) >> 24;
tmp[Slen + 1] = (i & 0x00ff0000) >> 16;
tmp[Slen + 2] = (i & 0x0000ff00) >> 8;
tmp[Slen + 3] = (i & 0x000000ff) >> 0;
rc = grub_crypto_hmac_buffer (md, P, Plen, tmp, tmplen, U);
}
else
rc = grub_crypto_hmac_buffer (md, P, Plen, U, hLen, U);
if (rc != GPG_ERR_NO_ERROR)
{
grub_free (tmp);
return rc;
}
for (k = 0; k < hLen; k++)
T[k] ^= U[k];
}
grub_memcpy (DK + (i - 1) * hLen, T, i == l ? r : hLen);
}
grub_free (tmp);
return GPG_ERR_NO_ERROR;
}
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