xemu/crypto/pbkdf-gcrypt.c
Daniel P. Berrange 59b060be18 crypto: use uint64_t for pbkdf iteration count parameters
The qcrypto_pbkdf_count_iters method uses a 64 bit int
but then checks its value against INT32_MAX before
returning it. This bounds check is premature, because
the calling code may well scale the iteration count
by some value. It is thus better to return a 64-bit
integer and let the caller do range checking.

For consistency the qcrypto_pbkdf method is also changed
to accept a 64bit int, though this is somewhat academic
since nettle is limited to taking an 'int' while gcrypt
is limited to taking a 'long int'.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2016-09-19 16:30:42 +01:00

77 lines
2.3 KiB
C

/*
* QEMU Crypto PBKDF support (Password-Based Key Derivation Function)
*
* Copyright (c) 2015-2016 Red Hat, Inc.
*
* This 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 of the License, or (at your option) any later version.
*
* This 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 this library; if not, see <http://www.gnu.org/licenses/>.
*
*/
#include "qemu/osdep.h"
#include <gcrypt.h>
#include "qapi/error.h"
#include "crypto/pbkdf.h"
bool qcrypto_pbkdf2_supports(QCryptoHashAlgorithm hash)
{
switch (hash) {
case QCRYPTO_HASH_ALG_MD5:
case QCRYPTO_HASH_ALG_SHA1:
case QCRYPTO_HASH_ALG_SHA256:
return true;
default:
return false;
}
}
int qcrypto_pbkdf2(QCryptoHashAlgorithm hash,
const uint8_t *key, size_t nkey,
const uint8_t *salt, size_t nsalt,
uint64_t iterations,
uint8_t *out, size_t nout,
Error **errp)
{
static const int hash_map[QCRYPTO_HASH_ALG__MAX] = {
[QCRYPTO_HASH_ALG_MD5] = GCRY_MD_MD5,
[QCRYPTO_HASH_ALG_SHA1] = GCRY_MD_SHA1,
[QCRYPTO_HASH_ALG_SHA256] = GCRY_MD_SHA256,
};
int ret;
if (iterations > ULONG_MAX) {
error_setg_errno(errp, ERANGE,
"PBKDF iterations %llu must be less than %lu",
(long long unsigned)iterations, ULONG_MAX);
return -1;
}
if (hash >= G_N_ELEMENTS(hash_map) ||
hash_map[hash] == GCRY_MD_NONE) {
error_setg(errp, "Unexpected hash algorithm %d", hash);
return -1;
}
ret = gcry_kdf_derive(key, nkey, GCRY_KDF_PBKDF2,
hash_map[hash],
salt, nsalt, iterations,
nout, out);
if (ret != 0) {
error_setg(errp, "Cannot derive password: %s",
gcry_strerror(ret));
return -1;
}
return 0;
}