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/*
* QEMU Crypto block IV generator - essiv
*
* 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 "qapi/error.h"
#include "qemu/bswap.h"
#include "crypto/ivgen-essiv.h"
typedef struct QCryptoIVGenESSIV QCryptoIVGenESSIV;
struct QCryptoIVGenESSIV {
QCryptoCipher *cipher;
};
static int qcrypto_ivgen_essiv_init(QCryptoIVGen *ivgen,
const uint8_t *key, size_t nkey,
Error **errp)
{
uint8_t *salt;
size_t nhash;
size_t nsalt;
QCryptoIVGenESSIV *essiv = g_new0(QCryptoIVGenESSIV, 1);
/* Not necessarily the same as nkey */
nsalt = qcrypto_cipher_get_key_len(ivgen->cipher);
nhash = qcrypto_hash_digest_len(ivgen->hash);
/* Salt must be larger of hash size or key size */
salt = g_new0(uint8_t, MAX(nhash, nsalt));
if (qcrypto_hash_bytes(ivgen->hash, (const gchar *)key, nkey,
&salt, &nhash,
errp) < 0) {
g_free(essiv);
g_free(salt);
return -1;
}
/* Now potentially truncate salt to match cipher key len */
essiv->cipher = qcrypto_cipher_new(ivgen->cipher,
QCRYPTO_CIPHER_MODE_ECB,
salt, MIN(nhash, nsalt),
errp);
if (!essiv->cipher) {
g_free(essiv);
g_free(salt);
return -1;
}
g_free(salt);
ivgen->private = essiv;
return 0;
}
static int qcrypto_ivgen_essiv_calculate(QCryptoIVGen *ivgen,
uint64_t sector,
uint8_t *iv, size_t niv,
Error **errp)
{
QCryptoIVGenESSIV *essiv = ivgen->private;
size_t ndata = qcrypto_cipher_get_block_len(ivgen->cipher);
uint8_t *data = g_new(uint8_t, ndata);
sector = cpu_to_le64(sector);
memcpy(data, (uint8_t *)§or, MIN(sizeof(sector), ndata));
if (sizeof(sector) < ndata) {
memset(data + sizeof(sector), 0, ndata - sizeof(sector));
}
if (qcrypto_cipher_encrypt(essiv->cipher,
data,
data,
ndata,
errp) < 0) {
g_free(data);
return -1;
}
if (ndata > niv) {
ndata = niv;
}
memcpy(iv, data, ndata);
if (ndata < niv) {
memset(iv + ndata, 0, niv - ndata);
}
g_free(data);
return 0;
}
static void qcrypto_ivgen_essiv_cleanup(QCryptoIVGen *ivgen)
{
QCryptoIVGenESSIV *essiv = ivgen->private;
qcrypto_cipher_free(essiv->cipher);
g_free(essiv);
}
struct QCryptoIVGenDriver qcrypto_ivgen_essiv = {
.init = qcrypto_ivgen_essiv_init,
.calculate = qcrypto_ivgen_essiv_calculate,
.cleanup = qcrypto_ivgen_essiv_cleanup,
};
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