/*

     File: QCCRSASmallCryptorT.h

 Abstract: Implements RSA encryption and decryption (using SecTransform API).

  Version: 1.0

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#import <Foundation/Foundation.h>

// IMPORTANT: This is for encrypting and decrypting small amounts of data, not an 

// entire file.  The standard technique for encrypting a large file is to 

// encrypt it with a symmetric algorithm (AES-128) using a randomly generated 

// key and then encrypt that key with RSA.  However, doing that sort of thing 

// correctly is a challenge and we recommend you use some standard encryption 

// scheme (such as CMS).

// 

// The exact definition of small depends on the key size and the padding in 

// use.  For example, a 2048-bit key with PKCS#1 padding can encrypt 245 bytes 

// (2048 bits -> 256 bytes - 11).  Don't ask me why or I'll start to whimper (-:

@interface QCCRSASmallCryptorT : NSOperation

- (id)initToEncryptSmallInputData:(NSData *)smallInputData key:(SecKeyRef)key;      // must be the *private* key

- (id)initToDecryptSmallInputData:(NSData *)smallInputData key:(SecKeyRef)key;      // must be the *public*  key

// properties set by the init method

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

@property (atomic, assign, readonly ) SecKeyRef     key;

// properties that may be set before running

// IMPORTANT: kQCCRSASmallCryptorTPaddingNone requires OS X 10.8 or later due to 

// limitations of the underlying security transform <rdar://problem/9987765>.

enum QCCRSASmallCryptorTPadding {

    kQCCRSASmallCryptorTPaddingNone,

    kQCCRSASmallCryptorTPaddingPKCS1                                    // the default

};

typedef enum QCCRSASmallCryptorTPadding QCCRSASmallCryptorTPadding;

@property (atomic, assign, readwrite) QCCRSASmallCryptorTPadding padding;

// properties set on finish

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

@property (atomic, copy,   readonly ) NSData *      smallOutputData;    // on successful encrypt, length match the key size (that is, for a 2048-bit key this will be 256 bytes)

                                                                        // on successful decrypt, length can be any value

@end