/*

    Copyright (C) 2016 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    Implements AES encryption and decryption without padding.

 */

@import Foundation;

NS_ASSUME_NONNULL_BEGIN

/*! Implements AES encryption and decryption without padding.

 *  \details In unpadded AES, both the input and output are an even multiple of 

 *      the AES block size (`kCCBlockSizeAES128`, or 16).  This supports both EBC and CBC 

 *      mode.

 *      

 *  \warning In most cases you will want to use AES in CBC mode; to do that securely, set the 

 *      initialisation vector (via the `ivData` property) to some cryptographically sound 

 *      random data.  If you need to use EBC mode, which is generally not recommended, set 

 *      the `ivData` property to nil.

 *      

 *  \note The designated initialiser for this class is private.  In the unlikely event you 

 *      need to subclass it, you will have to make that public.

 */

@interface QCCAESCryptor : NSOperation

/*! Initialise the object to encrypt data using a key.

 *  \param inputData The data to encrypt; its length must be an even multiple of the AES 

 *      block size (`kCCBlockSizeAES128`, or 16).

 *  \param keyData The key used to encrypt the data; its length must must be one of the 

 *      standard AES key sizes (128 bits, `kCCKeySizeAES128`, 16 bytes; 192 bits, 

 *      `kCCKeySizeAES192`, 24 bytes; 256 bits, `kCCKeySizeAES256`, or 32 bytes).

 *  \returns The initialised object.

 */

- (instancetype)initToEncryptInputData:(NSData *)inputData keyData:(NSData *)keyData;

/*! Initialise the object to decrypt data using a key.

 *  \param inputData The data to decrypt; its length must be an even multiple of the AES 

 *      block size (`kCCBlockSizeAES128`, or 16).

 *  \param keyData The key used to decrypt the data; its length must must be one of the 

 *      standard AES key sizes (128 bits, `kCCKeySizeAES128`, 16 bytes; 192 bits, 

 *      `kCCKeySizeAES192`, 24 bytes; 256 bits, `kCCKeySizeAES256`, or 32 bytes).

 *  \returns The initialised object.

 */

- (instancetype)initToDecryptInputData:(NSData *)inputData keyData:(NSData *)keyData;

- (instancetype)init NS_UNAVAILABLE;

/*! The data to be encrypted or decrypted.

 *  \details This is set by the init method.

 */

@property (atomic, copy,   readonly ) NSData *              inputData; 

/*! The key with which to do the encryption or decryption.

 *  \details This is set by the init method.

 */

@property (atomic, copy,   readonly ) NSData *              keyData; 

/*! The initialisation vector for the encryption or decryption. 

 *  \details Set this to nil to use EBC mode.  To use CBC mode securely, set this to an 

 *      initialisation vector generated by a cryptographically sound random number generator.  

 *      Its length must be the AES block size (`kCCBlockSizeAES128`, or 16).

 *      

 *      If you set this, you must set it before queuing the operation.

 *

 *  \warning The default value is an initialisation vector all zeroes.  This is not good 

 *      from a security standard, although still better than EBC mode.

 */

@property (atomic, copy,   readwrite, nullable) NSData *    ivData; 

/*! The error, if any, resulting from encryption or decryption operation.

 *  \details This is set when the operation is finished.  On success, it will be nil.  Or error, 

 *      it will hold a value describing that error.  You should expect errors to be in the 

 *      `QCCAESCryptorErrorDomain` error domain.

 */

@property (atomic, copy,   readonly, nullable) NSError *    error;

/*! The output data.

 *  \details This is only meaningful when the operation has finished without error.

 *      If this is an encryption operation, this will be the input data encrypted using the 

 *      key.  If this is a decryption operation, this will be the input data decrypted 

 *      using the key.  It both cases it will be the same length as the input data because 

 *      this operation does no padding.

 */

@property (atomic, copy,   readonly, nullable) NSData *     outputData;

@end

/*! The error domain for the QCCAESCryptor operation.

 *  \details Codes are Common Crypto error codes, that is, `kCCParamError` and its friends.

 */

extern NSString * QCCAESCryptorErrorDomain;

NS_ASSUME_NONNULL_END