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/*
* QEMU Crypto anti forensic information splitter
*
* Copyright (c) 2015-2016 Red Hat, Inc.
*
* Derived from cryptsetup package lib/luks1/af.c
*
* Copyright (C) 2004, Clemens Fruhwirth <clemens@endorphin.org>
* Copyright (C) 2009-2012, Red Hat, Inc. All rights reserved.
*
* This library 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
* 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 "qemu/bswap.h"
#include "crypto/afsplit.h"
#include "crypto/random.h"
static void qcrypto_afsplit_xor(size_t blocklen,
const uint8_t *in1,
const uint8_t *in2,
uint8_t *out)
{
size_t i;
for (i = 0; i < blocklen; i++) {
out[i] = in1[i] ^ in2[i];
}
}
static int qcrypto_afsplit_hash(QCryptoHashAlgorithm hash,
size_t blocklen,
uint8_t *block,
Error **errp)
{
size_t digestlen = qcrypto_hash_digest_len(hash);
size_t hashcount = blocklen / digestlen;
size_t finallen = blocklen % digestlen;
uint32_t i;
if (finallen) {
hashcount++;
} else {
finallen = digestlen;
}
for (i = 0; i < hashcount; i++) {
uint8_t *out = NULL;
size_t outlen = 0;
uint32_t iv = cpu_to_be32(i);
struct iovec in[] = {
{ .iov_base = &iv,
.iov_len = sizeof(iv) },
{ .iov_base = block + (i * digestlen),
.iov_len = (i == (hashcount - 1)) ? finallen : digestlen },
};
if (qcrypto_hash_bytesv(hash,
in,
G_N_ELEMENTS(in),
&out, &outlen,
errp) < 0) {
return -1;
}
assert(outlen == digestlen);
memcpy(block + (i * digestlen), out,
(i == (hashcount - 1)) ? finallen : digestlen);
g_free(out);
}
return 0;
}
int qcrypto_afsplit_encode(QCryptoHashAlgorithm hash,
size_t blocklen,
uint32_t stripes,
const uint8_t *in,
uint8_t *out,
Error **errp)
{
uint8_t *block = g_new0(uint8_t, blocklen);
size_t i;
int ret = -1;
for (i = 0; i < (stripes - 1); i++) {
if (qcrypto_random_bytes(out + (i * blocklen), blocklen, errp) < 0) {
goto cleanup;
}
qcrypto_afsplit_xor(blocklen,
out + (i * blocklen),
block,
block);
if (qcrypto_afsplit_hash(hash, blocklen, block,
errp) < 0) {
goto cleanup;
}
}
qcrypto_afsplit_xor(blocklen,
in,
block,
out + (i * blocklen));
ret = 0;
cleanup:
g_free(block);
return ret;
}
int qcrypto_afsplit_decode(QCryptoHashAlgorithm hash,
size_t blocklen,
uint32_t stripes,
const uint8_t *in,
uint8_t *out,
Error **errp)
{
uint8_t *block = g_new0(uint8_t, blocklen);
size_t i;
int ret = -1;
for (i = 0; i < (stripes - 1); i++) {
qcrypto_afsplit_xor(blocklen,
in + (i * blocklen),
block,
block);
if (qcrypto_afsplit_hash(hash, blocklen, block,
errp) < 0) {
goto cleanup;
}
}
qcrypto_afsplit_xor(blocklen,
in + (i * blocklen),
block,
out);
ret = 0;
cleanup:
g_free(block);
return ret;
}
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