7d9690148a
Add a generic framework for supporting different block encryption formats. Upon instantiating a QCryptoBlock object, it will read the encryption header and extract the encryption keys. It is then possible to call methods to encrypt/decrypt data buffers. There is also a mode whereby it will create/initialize a new encryption header on a previously unformatted volume. The initial framework comes with support for the legacy QCow AES based encryption. This enables code in the QCow driver to be consolidated later. Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
233 lines
7.6 KiB
C
233 lines
7.6 KiB
C
/*
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* QEMU Crypto block device encryption
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*
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* Copyright (c) 2015-2016 Red Hat, Inc.
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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 Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 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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#ifndef QCRYPTO_BLOCK_H__
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#define QCRYPTO_BLOCK_H__
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#include "crypto/cipher.h"
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#include "crypto/ivgen.h"
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typedef struct QCryptoBlock QCryptoBlock;
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/* See also QCryptoBlockFormat, QCryptoBlockCreateOptions
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* and QCryptoBlockOpenOptions in qapi/crypto.json */
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typedef ssize_t (*QCryptoBlockReadFunc)(QCryptoBlock *block,
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size_t offset,
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uint8_t *buf,
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size_t buflen,
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Error **errp,
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void *opaque);
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typedef ssize_t (*QCryptoBlockInitFunc)(QCryptoBlock *block,
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size_t headerlen,
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Error **errp,
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void *opaque);
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typedef ssize_t (*QCryptoBlockWriteFunc)(QCryptoBlock *block,
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size_t offset,
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const uint8_t *buf,
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size_t buflen,
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Error **errp,
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void *opaque);
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/**
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* qcrypto_block_has_format:
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* @format: the encryption format
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* @buf: the data from head of the volume
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* @len: the length of @buf in bytes
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*
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* Given @len bytes of data from the head of a storage volume
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* in @buf, probe to determine if the volume has the encryption
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* format specified in @format.
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*
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* Returns: true if the data in @buf matches @format
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*/
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bool qcrypto_block_has_format(QCryptoBlockFormat format,
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const uint8_t *buf,
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size_t buflen);
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typedef enum {
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QCRYPTO_BLOCK_OPEN_NO_IO = (1 << 0),
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} QCryptoBlockOpenFlags;
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/**
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* qcrypto_block_open:
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* @options: the encryption options
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* @readfunc: callback for reading data from the volume
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* @opaque: data to pass to @readfunc
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* @flags: bitmask of QCryptoBlockOpenFlags values
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* @errp: pointer to a NULL-initialized error object
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*
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* Create a new block encryption object for an existing
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* storage volume encrypted with format identified by
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* the parameters in @options.
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*
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* This will use @readfunc to initialize the encryption
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* context based on the volume header(s), extracting the
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* master key(s) as required.
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*
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* If @flags contains QCRYPTO_BLOCK_OPEN_NO_IO then
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* the open process will be optimized to skip any parts
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* that are only required to perform I/O. In particular
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* this would usually avoid the need to decrypt any
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* master keys. The only thing that can be done with
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* the resulting QCryptoBlock object would be to query
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* metadata such as the payload offset. There will be
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* no cipher or ivgen objects available.
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*
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* If any part of initializing the encryption context
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* fails an error will be returned. This could be due
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* to the volume being in the wrong format, a cipher
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* or IV generator algorithm that is not supported,
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* or incorrect passphrases.
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*
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* Returns: a block encryption format, or NULL on error
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*/
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QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
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QCryptoBlockReadFunc readfunc,
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void *opaque,
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unsigned int flags,
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Error **errp);
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/**
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* qcrypto_block_create:
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* @format: the encryption format
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* @initfunc: callback for initializing volume header
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* @writefunc: callback for writing data to the volume header
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* @opaque: data to pass to @initfunc and @writefunc
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* @errp: pointer to a NULL-initialized error object
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*
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* Create a new block encryption object for initializing
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* a storage volume to be encrypted with format identified
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* by the parameters in @options.
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*
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* This method will allocate space for a new volume header
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* using @initfunc and then write header data using @writefunc,
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* generating new master keys, etc as required. Any existing
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* data present on the volume will be irrevocably destroyed.
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*
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* If any part of initializing the encryption context
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* fails an error will be returned. This could be due
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* to the volume being in the wrong format, a cipher
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* or IV generator algorithm that is not supported,
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* or incorrect passphrases.
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*
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* Returns: a block encryption format, or NULL on error
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*/
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QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
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QCryptoBlockInitFunc initfunc,
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QCryptoBlockWriteFunc writefunc,
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void *opaque,
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Error **errp);
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/**
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* @qcrypto_block_decrypt:
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* @block: the block encryption object
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* @startsector: the sector from which @buf was read
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* @buf: the buffer to decrypt
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* @len: the length of @buf in bytes
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* @errp: pointer to a NULL-initialized error object
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*
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* Decrypt @len bytes of cipher text in @buf, writing
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* plain text back into @buf
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*
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* Returns 0 on success, -1 on failure
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*/
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int qcrypto_block_decrypt(QCryptoBlock *block,
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uint64_t startsector,
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uint8_t *buf,
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size_t len,
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Error **errp);
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/**
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* @qcrypto_block_encrypt:
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* @block: the block encryption object
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* @startsector: the sector to which @buf will be written
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* @buf: the buffer to decrypt
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* @len: the length of @buf in bytes
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* @errp: pointer to a NULL-initialized error object
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*
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* Encrypt @len bytes of plain text in @buf, writing
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* cipher text back into @buf
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*
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* Returns 0 on success, -1 on failure
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*/
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int qcrypto_block_encrypt(QCryptoBlock *block,
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uint64_t startsector,
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uint8_t *buf,
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size_t len,
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Error **errp);
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/**
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* qcrypto_block_get_cipher:
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* @block: the block encryption object
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*
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* Get the cipher to use for payload encryption
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*
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* Returns: the cipher object
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*/
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QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block);
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/**
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* qcrypto_block_get_ivgen:
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* @block: the block encryption object
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*
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* Get the initialization vector generator to use for
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* payload encryption
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*
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* Returns: the IV generator object
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*/
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QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block);
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/**
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* qcrypto_block_get_kdf_hash:
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* @block: the block encryption object
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*
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* Get the hash algorithm used with the key derivation
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* function
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*
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* Returns: the hash algorithm
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*/
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QCryptoHashAlgorithm qcrypto_block_get_kdf_hash(QCryptoBlock *block);
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/**
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* qcrypto_block_get_payload_offset:
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* @block: the block encryption object
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*
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* Get the offset to the payload indicated by the
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* encryption header, in bytes.
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*
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* Returns: the payload offset in bytes
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*/
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uint64_t qcrypto_block_get_payload_offset(QCryptoBlock *block);
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/**
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* qcrypto_block_free:
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* @block: the block encryption object
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*
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* Release all resources associated with the encryption
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* object
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*/
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void qcrypto_block_free(QCryptoBlock *block);
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#endif /* QCRYPTO_BLOCK_H__ */
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