//

 //  MYSymmetricKey-iPhone.m

 //  MYCrypto

 //

 //  Created by Jens Alfke on 4/17/09.

 //  Copyright 2009 Jens Alfke. All rights reserved.

 //

 #import "MYSymmetricKey.h"

 #import "MYCryptor.h"

 #import "MYCrypto_Private.h"

 #if MYCRYPTO_USE_IPHONE_API

 typedef uint32_t CSSM_ALGORITHMS;

 enum {

 // Taken from cssmtype.h in OS X 10.5 SDK:

 	CSSM_ALGID_NONE =					0x00000000L,

 	CSSM_ALGID_DES =					CSSM_ALGID_NONE + 14,

 	CSSM_ALGID_3DES_3KEY_EDE =			CSSM_ALGID_NONE + 17,

 	CSSM_ALGID_3DES_3KEY =           	CSSM_ALGID_3DES_3KEY_EDE,

 	CSSM_ALGID_RC4 =					CSSM_ALGID_NONE + 25,

 	CSSM_ALGID_CAST =					CSSM_ALGID_NONE + 27,

 	CSSM_ALGID_VENDOR_DEFINED =			CSSM_ALGID_NONE + 0x80000000L,

 	CSSM_ALGID_AES

 };

 static const CSSM_ALGORITHMS kCSSMAlgorithms[] = {

 CSSM_ALGID_AES, CSSM_ALGID_DES, CSSM_ALGID_3DES_3KEY, CSSM_ALGID_CAST, CSSM_ALGID_RC4

 };

 static const char *kCCAlgorithmNames[] = {"AES", "DES", "DES^3", "CAST", "RC4"};

 @implementation MYSymmetricKey

 - (id) _initWithKeyData: (NSData*)keyData

               algorithm: (CCAlgorithm)algorithm

              inKeychain: (MYKeychain*)keychain

 {

     Assert(algorithm <= kCCAlgorithmRC4);

     Assert(keyData);

     NSNumber *keySizeInBits = [NSNumber numberWithUnsignedInt: keyData.length * 8];

     NSNumber *keyType = [NSNumber numberWithUnsignedInt: kCSSMAlgorithms[algorithm]];

     NSMutableDictionary *keyAttrs = $mdict( {(id)kSecClass, (id)kSecClassKey},

                                             {(id)kSecAttrKeyClass, (id)kSecAttrKeyClassSymmetric},

                                             {(id)kSecAttrKeyType, keyType},

                                             {(id)kSecValueData, keyData},

                                             {(id)kSecAttrKeySizeInBits, keySizeInBits},

                                             {(id)kSecAttrEffectiveKeySize, keySizeInBits},

                                             {(id)kSecAttrIsPermanent, keychain ?$true :$false},

                                             {(id)kSecAttrCanEncrypt, $true},

                                             {(id)kSecAttrCanDecrypt, $true},

                                             {(id)kSecAttrCanWrap, $false},

                                             {(id)kSecAttrCanUnwrap, $false},

                                             {(id)kSecAttrCanDerive, $false},

                                             {(id)kSecAttrCanSign, $false},

                                             {(id)kSecAttrCanVerify, $false},

                                             {(id)kSecReturnPersistentRef, $true});

     SecKeyRef keyRef = [[self class] _addKeyWithInfo: keyAttrs];

     if (!keyRef) {

         [self release];

         return nil;

     }

     self = [self initWithKeyRef: keyRef];

     CFRelease(keyRef);

     return self;

 }

 - (id) initWithKeyData: (NSData*)keyData

              algorithm: (CCAlgorithm)algorithm

 {

     return [self _initWithKeyData: keyData algorithm: algorithm inKeychain: nil];

 }

 + (MYSymmetricKey*) _generateSymmetricKeyOfSize: (unsigned)keySizeInBits

                                       algorithm: (CCAlgorithm)algorithm

                                      inKeychain: (MYKeychain*)keychain

 {

     return [[[self alloc] _initWithKeyData: [MYCryptor randomKeyOfLength: keySizeInBits]

                                  algorithm: algorithm

                                 inKeychain: keychain]

                     autorelease];

 }

 + (MYSymmetricKey*) generateSymmetricKeyOfSize: (unsigned)keySizeInBits

                                      algorithm: (CCAlgorithm)algorithm {

     return [self _generateSymmetricKeyOfSize: keySizeInBits

                                    algorithm: algorithm

                                   inKeychain: nil];

 }

 - (SecExternalItemType) keyClass {

     return kSecAttrKeyClassSymmetric;

 }

 - (CCAlgorithm) algorithm {

     CSSM_ALGORITHMS cssmAlg;

     id keyType = [self _attribute: kSecAttrKeyType];

     Assert(keyType!=nil, @"Key has no kSecAttrKeyType");

     cssmAlg = [keyType unsignedIntValue];

     switch(cssmAlg) {

         case CSSM_ALGID_AES:

             return kCCAlgorithmAES128;

         case CSSM_ALGID_DES:

             return kCCAlgorithmDES;	

         case CSSM_ALGID_3DES_3KEY:

             return kCCAlgorithm3DES;

         case CSSM_ALGID_CAST:

             return kCCAlgorithmCAST;

         case CSSM_ALGID_RC4:

             return kCCAlgorithmRC4;	

         default:

             Warn(@"CSSM_ALGORITHMS #%u doesn't map to any CCAlgorithm", cssmAlg);

             return (CCAlgorithm)-1;

     }

 }

 - (const char*) algorithmName {

     CCAlgorithm a = self.algorithm;

     if (a >= 0 && a <= kCCAlgorithmRC4)

         return kCCAlgorithmNames[a];

     else

         return "???";

 }

 - (unsigned) keySizeInBits {

     id keySize = [self _attribute: kSecAttrKeySizeInBits];

     Assert(keySize!=nil, @"Key has no kSecAttrKeySizeInBits");

     return [keySize unsignedIntValue];

 }

 - (NSString*) description {

     return $sprintf(@"%@[%u-bit %s]", [self class], self.keySizeInBits, self.algorithmName);

 }

 - (NSData*) _cryptData: (NSData*)data operation: (CCOperation)op options: (CCOptions)options

 {

     NSData *keyData = self.keyData;

     Assert(keyData, @"Couldn't get key data");

     NSMutableData *output = [NSMutableData dataWithLength: data.length + 256];

     size_t bytesWritten = 0;

     CCCryptorStatus status = CCCrypt(op, self.algorithm, options, 

                                      keyData.bytes, keyData.length, NULL,

                                      data.bytes, data.length, output.mutableBytes, output.length,

                                      &bytesWritten);

     if (status) {

         Warn(@"MYSymmetricKey: CCCrypt returned error %i",status);

         return nil;

     }

     output.length = bytesWritten;

     return output;

 }

 - (NSData*) encryptData: (NSData*)data {

     return [self _cryptData: data operation: kCCEncrypt options: kCCOptionPKCS7Padding];

 }

 - (NSData*) decryptData: (NSData*)data {

     return [self _cryptData: data operation: kCCDecrypt options: kCCOptionPKCS7Padding];

 }

 @end

 #endif MYCRYPTO_USE_IPHONE_API

 /*

  Copyright (c) 2009, Jens Alfke <jens@mooseyard.com>. All rights reserved.

  Redistribution and use in source and binary forms, with or without modification, are permitted

  provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice, this list of conditions

  and the following disclaimer.

  * Redistributions in binary form must reproduce the above copyright notice, this list of conditions

  and the following disclaimer in the documentation and/or other materials provided with the

  distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR

  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 

  FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRI-

  BUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 

   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 

  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 

  THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

  */