/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017
* Jonathan Schleifer <js@heap.zone>
*
* All rights reserved.
*
* This file is part of ObjFW. It may be distributed under the terms of the
* Q Public License 1.0, which can be found in the file LICENSE.QPL included in
* the packaging of this file.
*
* Alternatively, it may be distributed under the terms of the GNU General
* Public License, either version 2 or 3, which can be found in the file
* LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
* file.
*/
#import "OFObject.h"
#import "OFCryptoHash.h"
OF_ASSUME_NONNULL_BEGIN
/*!
* @class OFHMAC OFHMAC.h ObjFW/OFHMAC.h
*
* @brief A class which provides methods to calculate an HMAC.
*/
@interface OFHMAC: OFObject
{
Class <OFCryptoHash> _hashClass;
id <OFCryptoHash> _Nullable _outerHash, _innerHash;
id <OFCryptoHash> _Nullable _outerHashCopy, _innerHashCopy;
bool _calculated;
}
/*!
* @brief The class for the cryptographic hash used by the HMAC.
*/
@property (readonly, nonatomic) Class <OFCryptoHash> hashClass;
/*!
* @brief A buffer containing the HMAC.
*
* The size of the buffer depends on the hash used. The buffer is part of the
* receiver's memory pool.
*/
@property (readonly, nonatomic) const unsigned char *digest
OF_RETURNS_INNER_POINTER;
/*!
* @brief The size of the digest.
*/
@property (readonly, nonatomic) size_t digestSize;
/*!
* @brief Returns a new OFHMAC with the specified hashing algorithm.
*
* @param hashClass The class of the hashing algorithm
* @return A new, autoreleased OFHMAC
*/
+ (instancetype)HMACWithHashClass: (Class <OFCryptoHash>)hashClass;
- (instancetype)init OF_UNAVAILABLE;
/*!
* @brief Initialized an already allocated OFHMAC with the specified hashing
* algorithm.
*
* @param hashClass The class of the hashing algorithm
* @return An initialized OFHMAC
*/
- (instancetype)initWithHashClass: (Class <OFCryptoHash>)hashClass
OF_DESIGNATED_INITIALIZER;
/*!
* @brief Sets the key for the HMAC.
*
* @note This resets the HMAC!
*
* @warning This invalidates any pointer previously returned by @ref digest. If
* you are still interested in the previous digest, you need to memcpy
* it yourself before calling @ref setKey:length:!
*
* @param key The key for the HMAC
* @param length The length of the key for the HMAC
*/
- (void)setKey: (const void *)key
length: (size_t)length;
/*!
* @brief Adds a buffer to the HMAC to be calculated.
*
* @param buffer The buffer which should be included into the calculation
* @param length The length of the buffer
*/
- (void)updateWithBuffer: (const void *)buffer
length: (size_t)length;
/*!
* @brief Resets the HMAC so that it can be calculated for a new message.
*
* @note This does not reset the key so that a new HMAC with the same key can
* be calculated efficiently. If you want to reset both, use
* @ref setKey:length:.
*
* @warning This invalidates any pointer previously returned by @ref digest. If
* you are still interested in the previous digest, you need to memcpy
* it yourself before calling @ref reset!
*/
- (void)reset;
/*!
* @brief This is like @ref reset, but also zeroes the hashed key and all state.
*
* @warning After calling this, you *must* set a new key before reusing the
* HMAC!
*/
- (void)zero;
@end
OF_ASSUME_NONNULL_END