//

//  MYPrivateKey.h

//  MYCrypto

//

//  Created by Jens Alfke on 4/7/09.

//  Copyright 2009 Jens Alfke. All rights reserved.

//

#import "MYKey.h"

#import <CommonCrypto/CommonCryptor.h>

@class MYPublicKey, MYSHA1Digest, MYIdentity, MYSymmetricKey;

/** A private key, used for signing and decrypting data.

    Always paired with a matching public key in a "key-pair".

    MYPublicKeys are instantiated by MYKeychain: either by generating a new key-pair, by

    looking up a key-pair by its attributes, or by importing a key-pair from data. */

@interface MYPrivateKey : MYKey

{

    @private

    MYPublicKey *_publicKey;

}

/** The matching public key. Always non-nil. */

@property (readonly) MYPublicKey *publicKey;

/** The public key's SHA-1 digest. 

    This is a convenient short (20-byte) identifier for the key pair. You can store it in your

    application data, and then later look up either key using MYKeychain methods. */

@property (readonly) MYSHA1Digest *publicKeyDigest;

/** Decrypts data that was encrypted using the public key.

    See the description of -[MYPublicKey encryptData:] for warnings and caveats.

    This method is usually used only to decrypt a symmetric session key, which then decrypts the

    rest of the data. */

- (NSData*) rawDecryptData: (NSData*)data;

/** Generates a signature of data.

    (What's actually signed using RSA is the SHA-256 digest of the data.)

    The resulting signature can be verified using the matching MYPublicKey's

    verifySignature:ofData: method. */

- (NSData*) signData: (NSData*)data;

/** @name Mac-Only

 *  Functionality not available on iPhone. 

 */

//@{

#if !TARGET_OS_IPHONE

/** Exports the private key as a data blob, so that it can be stored as a backup, or transferred

    to another computer. Since the key is sensitive, it must be exported in encrypted form

    using a user-chosen passphrase. This method will display a standard alert panel, run by

    the Security agent, that prompts the user to enter a new passphrase for encrypting the key.

    The same passphrase must be re-entered when importing the key from the data blob.

    (This is a convenient shorthand for the full exportPrivateKeyInFormat... method.

    It uses OpenSSL format, wrapped with PEM, and a default title and prompt for the alert.) */

- (NSData*) exportKey;

/** Exports the private key as a data blob, so that it can be stored as a backup, or transferred

    to another computer. Since the key is sensitive, it must be exported in encrypted form

    using a user-chosen passphrase. This method will display a standard alert panel, run by

    the Security agent, that prompts the user to enter a new passphrase for encrypting the key.

    The same passphrase must be re-entered when importing the key from the data blob.

    @param format  The data format: kSecFormatOpenSSL, kSecFormatSSH, kSecFormatBSAFE or kSecFormatSSHv2.

    @param withPEM  YES if the data should be encoded in PEM format, which converts into short lines

        of printable ASCII characters, suitable for sending in email.

    @param alertTitle  An optional title for the alert panel. (Currently ignored by the OS?)

    @param prompt  An optional prompt message to display in the alert panel. */

- (NSData*) exportKeyInFormat: (SecExternalFormat)format

                      withPEM: (BOOL)withPEM

                   alertTitle: (NSString*)alertTitle

                  alertPrompt: (NSString*)prompt;

/** Decrypts a session key that was wrapped (encrypted) using my matching public key.

    @param wrappedData  The wrapped/encrypted session key

    @param algorithm  The algorithm of the original session key

    @param sizeInBits  The key size (in bits) of the original session key

    @return  The reconstituted session key */

- (MYSymmetricKey*) unwrapSessionKey: (NSData*)wrappedData

                       withAlgorithm: (CCAlgorithm)algorithm

                          sizeInBits: (unsigned)sizeInBits;

#endif

//@}

@end