Application "crashes" when i try to decrypt the CipherBuffer the second time - ios

Question

Hello i am trying to implement an iPhone app the takes notes and encrypts them and then decrypts them when you enter the correct PIN on a UIAlertView. When the Application loads for the first time i have included in my AppDelegate some code thats checks if there is already a public and private key. If not it goes and generates a pair and adds them to the internal storage. When the application starts for the first time it works just fine. Then i terminate the app and open it again and it just hangs when i go into an existing note and try to decrypt it. From the console i can see the it loads the cipher buffer in the decryption method but the textView is never loaded with the decrypted text this time. The Button just stays in a pressed like state and the process doesn't terminate. this is the code.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *data2 = [defaults objectForKey:#"publicKey"];
if (data2 == nil) {
encrypt = [[SecKey alloc]init];
[encrypt generateKeyPairRSA];
SecKeyRef publicKey =[encrypt getPublicKeyRef];
SecKeyRef privateKey = [encrypt getPrivateKeyRef];
size_t keySize = SecKeyGetBlockSize(publicKey);
NSData* keyData = [NSData dataWithBytes:publicKey length:keySize];
[[NSUserDefaults standardUserDefaults] setObject:keyData forKey:#"publicKey"];
keySize = SecKeyGetBlockSize(privateKey);
keyData = [NSData dataWithBytes:privateKey length:keySize];
[[NSUserDefaults standardUserDefaults] setObject:keyData forKey:#"privateKey"];
}
When i run the application for the first time this works fine.
- (IBAction)save:(id)sender {
//save the context and dismiss the AddNewNotesViewcontroller
uint8_t *cipherBuffer = NULL;
SecKey *encrypt = [[SecKey alloc]init];
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *data2 = [defaults objectForKey:#"publicKey"];
encrypt.publicKey =(SecKeyRef)[data2 bytes];
cipherBuffer = [encrypt Encryption:plainTextField.text];
NSMutableData *data = [[NSMutableData alloc]init];
[data appendBytes:cipherBuffer length:strlen((char*)cipherBuffer)+1];
[self.currentNote setNotesTitle:titleField.text];
[self.currentNote setEncryptedText:data];
[self.delegate addNewNoteViewControllerDidSave];
}
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{
NSString *title = [alertView buttonTitleAtIndex:buttonIndex];
if([title isEqualToString:#"Decrypt"])
{
UITextField *passcode = [alertView textFieldAtIndex:0];
if ([passcode.text isEqual: #"1234"]) {
SecKey *encrypt = [[SecKey alloc]init];
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
NSData *data2 = [defaults objectForKey:#"publicKey"];
encrypt.publicKey =(SecKeyRef)[data2 bytes];
data2 = [defaults objectForKey:#"privateKey"];
encrypt.privateKey =(SecKeyRef)[data2 bytes];
NSData *etData = [[NSData alloc]init];
etData = [self.currentNote encryptedText];
const void *bytes = [etData bytes];
uint8_t *crypto_data = (uint8_t*)bytes;
NSLog(#"test %s",crypto_data);
NSString *pb =[encrypt Decryption:crypto_data];
self.encryptedText.text =pb;
}
else self.encryptedText.text = #"WRONG PASSWORD";
}
}
This is the decryption process
- (void)decryptWithPrivateKey:(uint8_t *)cipherBuffer plainBuffer:(uint8_t *)plainBuffer
{
OSStatus status = noErr;
size_t cipherBufferSize = strlen((char *)cipherBuffer);
NSLog(#"decryptWithPrivateKey: length of buffer: %lu", BUFFER_SIZE);
NSLog(#"decryptWithPrivateKey: length of input: %lu", cipherBufferSize);
size_t plainBufferSize = BUFFER_SIZE;
status = SecKeyDecrypt([self getPrivateKey],
PADDING,
&cipherBuffer[0],
cipherBufferSize,
&plainBuffer[0],
&plainBufferSize
);
NSLog(#"decryption result code: %ld (size: %lu)", status, plainBufferSize);
NSLog(#"FINAL decrypted text: %s", plainBuffer);
}
-(NSString *)Decryption:(uint8_t *)cipherBuffer {
plainBuffer = (uint8_t *)calloc(CIPHER_BUFFER_SIZE, sizeof(uint8_t));
[self decryptWithPrivateKey:cipherBuffer plainBuffer:plainBuffer];
NSLog(#"DECRYPTED DATA : %s",plainBuffer);
NSString *s = [[NSString alloc] initWithBytes:plainBuffer length:BUFFER_SIZE encoding:NSUTF8StringEncoding];
return s;
}
Any ideas why this is happening? I am guessing it must be that when it tries to retrieve the private key from the NSUserDefaults. Because the first time when the pair is created it is stored in the NSUserDefaults but it is not retrieved later when i decrypt a note because i haven't close the app yet.