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/*
* QEMU Crypto block IV generator
*
* 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/>.
*
*/
#ifndef QCRYPTO_IVGEN_H
#define QCRYPTO_IVGEN_H
#include "crypto/cipher.h"
#include "crypto/hash.h"
/**
* This module provides a framework for generating initialization
* vectors for block encryption schemes using chained cipher modes
* CBC. The principle is that each disk sector is assigned a unique
* initialization vector for use for encryption of data in that
* sector.
*
* <example>
* <title>Encrypting block data with initialiation vectors</title>
* <programlisting>
* uint8_t *data = ....data to encrypt...
* size_t ndata = XXX;
* uint8_t *key = ....some encryption key...
* size_t nkey = XXX;
* uint8_t *iv;
* size_t niv;
* size_t sector = 0;
*
* g_assert((ndata % 512) == 0);
*
* QCryptoIVGen *ivgen = qcrypto_ivgen_new(QCRYPTO_IVGEN_ALG_ESSIV,
* QCRYPTO_CIPHER_ALG_AES_128,
* QCRYPTO_HASH_ALG_SHA256,
* key, nkey, errp);
* if (!ivgen) {
* return -1;
* }
*
* QCryptoCipher *cipher = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_128,
* QCRYPTO_CIPHER_MODE_CBC,
* key, nkey, errp);
* if (!cipher) {
* goto error;
* }
*
* niv = qcrypto_cipher_get_iv_len(QCRYPTO_CIPHER_ALG_AES_128,
* QCRYPTO_CIPHER_MODE_CBC);
* iv = g_new0(uint8_t, niv);
*
*
* while (ndata) {
* if (qcrypto_ivgen_calculate(ivgen, sector, iv, niv, errp) < 0) {
* goto error;
* }
* if (qcrypto_cipher_setiv(cipher, iv, niv, errp) < 0) {
* goto error;
* }
* if (qcrypto_cipher_encrypt(cipher,
* data + (sector * 512),
* data + (sector * 512),
* 512, errp) < 0) {
* goto error;
* }
* sector++;
* ndata -= 512;
* }
*
* g_free(iv);
* qcrypto_ivgen_free(ivgen);
* qcrypto_cipher_free(cipher);
* return 0;
*
*error:
* g_free(iv);
* qcrypto_ivgen_free(ivgen);
* qcrypto_cipher_free(cipher);
* return -1;
* </programlisting>
* </example>
*/
typedef struct QCryptoIVGen QCryptoIVGen;
/* See also QCryptoIVGenAlgorithm enum in qapi/crypto.json */
/**
* qcrypto_ivgen_new:
* @alg: the initialization vector generation algorithm
* @cipheralg: the cipher algorithm or 0
* @hash: the hash algorithm or 0
* @key: the encryption key or NULL
* @nkey: the size of @key in bytes
*
* Create a new initialization vector generator that uses
* the algorithm @alg. Whether the remaining parameters
* are required or not depends on the choice of @alg
* requested.
*
* - QCRYPTO_IVGEN_ALG_PLAIN
*
* The IVs are generated by the 32-bit truncated sector
* number. This should never be used for block devices
* that are larger than 2^32 sectors in size.
* All the other parameters are unused.
*
* - QCRYPTO_IVGEN_ALG_PLAIN64
*
* The IVs are generated by the 64-bit sector number.
* All the other parameters are unused.
*
* - QCRYPTO_IVGEN_ALG_ESSIV:
*
* The IVs are generated by encrypting the 64-bit sector
* number with a hash of an encryption key. The @cipheralg,
* @hash, @key and @nkey parameters are all required.
*
* Returns: a new IV generator, or NULL on error
*/
QCryptoIVGen *qcrypto_ivgen_new(QCryptoIVGenAlgorithm alg,
QCryptoCipherAlgorithm cipheralg,
QCryptoHashAlgorithm hash,
const uint8_t *key, size_t nkey,
Error **errp);
/**
* qcrypto_ivgen_calculate:
* @ivgen: the IV generator object
* @sector: the 64-bit sector number
* @iv: a pre-allocated buffer to hold the generated IV
* @niv: the number of bytes in @iv
* @errp: pointer to a NULL-initialized error object
*
* Calculate a new initialiation vector for the data
* to be stored in sector @sector. The IV will be
* written into the buffer @iv of size @niv.
*
* Returns: 0 on success, -1 on error
*/
int qcrypto_ivgen_calculate(QCryptoIVGen *ivgen,
uint64_t sector,
uint8_t *iv, size_t niv,
Error **errp);
/**
* qcrypto_ivgen_get_algorithm:
* @ivgen: the IV generator object
*
* Get the algorithm used by this IV generator
*
* Returns: the IV generator algorithm
*/
QCryptoIVGenAlgorithm qcrypto_ivgen_get_algorithm(QCryptoIVGen *ivgen);
/**
* qcrypto_ivgen_get_cipher:
* @ivgen: the IV generator object
*
* Get the cipher algorithm used by this IV generator (if
* applicable)
*
* Returns: the cipher algorithm
*/
QCryptoCipherAlgorithm qcrypto_ivgen_get_cipher(QCryptoIVGen *ivgen);
/**
* qcrypto_ivgen_get_hash:
* @ivgen: the IV generator object
*
* Get the hash algorithm used by this IV generator (if
* applicable)
*
* Returns: the hash algorithm
*/
QCryptoHashAlgorithm qcrypto_ivgen_get_hash(QCryptoIVGen *ivgen);
/**
* qcrypto_ivgen_free:
* @ivgen: the IV generator object
*
* Release all resources associated with @ivgen, or a no-op
* if @ivgen is NULL
*/
void qcrypto_ivgen_free(QCryptoIVGen *ivgen);
#endif /* QCRYPTO_IVGEN_H */
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