Asmmetric keypair generation

gistfile1.m

- (void)generateKeyPair:(NSUInteger)keySize {
	OSStatus sanityCheck = noErr;
	publicKeyRef = NULL;
	privateKeyRef = NULL;
	
	LOGGING_FACILITY1( keySize == 512 || keySize == 1024 || keySize == 2048, @"%d is an invalid and unsupported key size.", keySize );
	
	// First delete current keys.
	[self deleteAsymmetricKeys];
	
	// Container dictionaries.
	NSMutableDictionary * privateKeyAttr = [[NSMutableDictionary alloc] init];
	NSMutableDictionary * publicKeyAttr = [[NSMutableDictionary alloc] init];
	NSMutableDictionary * keyPairAttr = [[NSMutableDictionary alloc] init];
	
	// Set top level dictionary for the keypair.
	[keyPairAttr setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
	[keyPairAttr setObject:[NSNumber numberWithUnsignedInteger:keySize] forKey:(id)kSecAttrKeySizeInBits];
	
	// Set the private key dictionary.
	[privateKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrIsPermanent];
	[privateKeyAttr setObject:privateTag forKey:(id)kSecAttrApplicationTag];
	// See SecKey.h to set other flag values.
	
	// Set the public key dictionary.
	[publicKeyAttr setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecAttrIsPermanent];
	[publicKeyAttr setObject:publicTag forKey:(id)kSecAttrApplicationTag];
	// See SecKey.h to set other flag values.
	
	// Set attributes to top level dictionary.
	[keyPairAttr setObject:privateKeyAttr forKey:(id)kSecPrivateKeyAttrs];
	[keyPairAttr setObject:publicKeyAttr forKey:(id)kSecPublicKeyAttrs];
	
	// SecKeyGeneratePair returns the SecKeyRefs just for educational purposes.
	sanityCheck = SecKeyGeneratePair((CFDictionaryRef)keyPairAttr, &publicKeyRef, &privateKeyRef);
	LOGGING_FACILITY( sanityCheck == noErr && publicKeyRef != NULL && privateKeyRef != NULL, @"Something really bad went wrong with generating the key pair." );
	
	[privateKeyAttr release];
	[publicKeyAttr release];
	[keyPairAttr release];
}

- (void)deleteAsymmetricKeys {
	OSStatus sanityCheck = noErr;
	NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];
	NSMutableDictionary * queryPrivateKey = [[NSMutableDictionary alloc] init];
	
	// Set the public key query dictionary.
	[queryPublicKey setObject:(id)kSecClassKey forKey:(id)kSecClass];
	[queryPublicKey setObject:publicTag forKey:(id)kSecAttrApplicationTag];
	[queryPublicKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
	
	// Set the private key query dictionary.
	[queryPrivateKey setObject:(id)kSecClassKey forKey:(id)kSecClass];
	[queryPrivateKey setObject:privateTag forKey:(id)kSecAttrApplicationTag];
	[queryPrivateKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
	
	// Delete the private key.
	sanityCheck = SecItemDelete((CFDictionaryRef)queryPrivateKey);
	LOGGING_FACILITY1( sanityCheck == noErr || sanityCheck == errSecItemNotFound, @"Error removing private key, OSStatus == %d.", sanityCheck );
	
	// Delete the public key.
	sanityCheck = SecItemDelete((CFDictionaryRef)queryPublicKey);
	LOGGING_FACILITY1( sanityCheck == noErr || sanityCheck == errSecItemNotFound, @"Error removing public key, OSStatus == %d.", sanityCheck );
	
	[queryPrivateKey release];
	[queryPublicKey release];
	if (publicKeyRef) CFRelease(publicKeyRef);
	if (privateKeyRef) CFRelease(privateKeyRef);
}

- (SecKeyRef)getPublicKeyRef {
	OSStatus sanityCheck = noErr;
	SecKeyRef publicKeyReference = NULL;
	
	if (publicKeyRef == NULL) {
		NSMutableDictionary * queryPublicKey = [[NSMutableDictionary alloc] init];
		
		// Set the public key query dictionary.
		[queryPublicKey setObject:(id)kSecClassKey forKey:(id)kSecClass];
		[queryPublicKey setObject:publicTag forKey:(id)kSecAttrApplicationTag];
		[queryPublicKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
		[queryPublicKey setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecReturnRef];
		
		// Get the key.
		sanityCheck = SecItemCopyMatching((CFDictionaryRef)queryPublicKey, (CFTypeRef *)&publicKeyReference);
		
		if (sanityCheck != noErr)
		{
			publicKeyReference = NULL;
		}
		
		[queryPublicKey release];
	} else {
		publicKeyReference = publicKeyRef;
	}
	
	return publicKeyReference;
}

- (SecKeyRef)getPrivateKeyRef {
	OSStatus sanityCheck = noErr;
	SecKeyRef privateKeyReference = NULL;
	
	if (privateKeyRef == NULL) {
		NSMutableDictionary * queryPrivateKey = [[NSMutableDictionary alloc] init];
		
		// Set the private key query dictionary.
		[queryPrivateKey setObject:(id)kSecClassKey forKey:(id)kSecClass];
		[queryPrivateKey setObject:privateTag forKey:(id)kSecAttrApplicationTag];
		[queryPrivateKey setObject:(id)kSecAttrKeyTypeRSA forKey:(id)kSecAttrKeyType];
		[queryPrivateKey setObject:[NSNumber numberWithBool:YES] forKey:(id)kSecReturnRef];
		
		// Get the key.
		sanityCheck = SecItemCopyMatching((CFDictionaryRef)queryPrivateKey, (CFTypeRef *)&privateKeyReference);
		
		if (sanityCheck != noErr)
		{
			privateKeyReference = NULL;
		}
		
		[queryPrivateKey release];
	} else {
		privateKeyReference = privateKeyRef;
	}
	
	return privateKeyReference;
}