160 lines
4.4 KiB
C
160 lines
4.4 KiB
C
/*
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* QEMU Crypto anti forensic information splitter
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*
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* Copyright (c) 2015-2016 Red Hat, Inc.
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*
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* Derived from cryptsetup package lib/luks1/af.c
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*
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* Copyright (C) 2004, Clemens Fruhwirth <clemens@endorphin.org>
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* Copyright (C) 2009-2012, Red Hat, Inc. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "qemu/bswap.h"
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#include "crypto/afsplit.h"
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#include "crypto/random.h"
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static void qcrypto_afsplit_xor(size_t blocklen,
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const uint8_t *in1,
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const uint8_t *in2,
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uint8_t *out)
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{
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size_t i;
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for (i = 0; i < blocklen; i++) {
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out[i] = in1[i] ^ in2[i];
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}
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}
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static int qcrypto_afsplit_hash(QCryptoHashAlgorithm hash,
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size_t blocklen,
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uint8_t *block,
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Error **errp)
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{
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size_t digestlen = qcrypto_hash_digest_len(hash);
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size_t hashcount = blocklen / digestlen;
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size_t finallen = blocklen % digestlen;
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uint32_t i;
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if (finallen) {
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hashcount++;
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} else {
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finallen = digestlen;
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}
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for (i = 0; i < hashcount; i++) {
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uint8_t *out = NULL;
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size_t outlen = 0;
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uint32_t iv = cpu_to_be32(i);
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struct iovec in[] = {
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{ .iov_base = &iv,
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.iov_len = sizeof(iv) },
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{ .iov_base = block + (i * digestlen),
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.iov_len = (i == (hashcount - 1)) ? finallen : digestlen },
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};
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if (qcrypto_hash_bytesv(hash,
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in,
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G_N_ELEMENTS(in),
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&out, &outlen,
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errp) < 0) {
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return -1;
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}
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assert(outlen == digestlen);
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memcpy(block + (i * digestlen), out,
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(i == (hashcount - 1)) ? finallen : digestlen);
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g_free(out);
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}
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return 0;
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}
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int qcrypto_afsplit_encode(QCryptoHashAlgorithm hash,
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size_t blocklen,
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uint32_t stripes,
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const uint8_t *in,
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uint8_t *out,
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Error **errp)
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{
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uint8_t *block = g_new0(uint8_t, blocklen);
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size_t i;
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int ret = -1;
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for (i = 0; i < (stripes - 1); i++) {
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if (qcrypto_random_bytes(out + (i * blocklen), blocklen, errp) < 0) {
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goto cleanup;
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}
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qcrypto_afsplit_xor(blocklen,
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out + (i * blocklen),
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block,
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block);
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if (qcrypto_afsplit_hash(hash, blocklen, block,
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errp) < 0) {
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goto cleanup;
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}
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}
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qcrypto_afsplit_xor(blocklen,
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in,
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block,
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out + (i * blocklen));
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ret = 0;
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cleanup:
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g_free(block);
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return ret;
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}
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int qcrypto_afsplit_decode(QCryptoHashAlgorithm hash,
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size_t blocklen,
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uint32_t stripes,
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const uint8_t *in,
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uint8_t *out,
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Error **errp)
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{
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uint8_t *block = g_new0(uint8_t, blocklen);
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size_t i;
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int ret = -1;
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for (i = 0; i < (stripes - 1); i++) {
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qcrypto_afsplit_xor(blocklen,
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in + (i * blocklen),
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block,
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block);
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if (qcrypto_afsplit_hash(hash, blocklen, block,
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errp) < 0) {
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goto cleanup;
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}
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}
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qcrypto_afsplit_xor(blocklen,
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in + (i * blocklen),
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block,
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out);
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ret = 0;
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cleanup:
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g_free(block);
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return ret;
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}
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