CCCrypt difference between iOS5 and iOS6

Question

I have got a decryption/encryption method using CCCrypt() which worked really well on iOS5. Now I am working with the iOS6 SDK and never changed my code, but it

Answer 1

There is an apple developer forum thread discussing this issue and it has a good amount of info on the topic. It seems that the padding option is an issue for many people. Comment #11 is where the solution starts to be discussed.

Answer 2

I'm not an expert i encryption, but I have the same problem and figured a workaround maybe it will be fine until some will find a real solution.

all I did is to figure which iOS is running and for 6+ i'm changing the CCCrypt call to no padding (0 is for no padding, 1 is the enum for kCCOptionPKCS7Padding)

float version = [[UIDevice currentDevice].systemVersion floatValue];
if (version >= 6)
{
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, 0,
                                          keyPtr, kCCKeySizeAES128,
                                          ivPtr,
                                          [self bytes], dataLength,
                                          buffer, bufferSize, 
                                          &numBytesDecrypted );


    if( cryptStatus == kCCSuccess )
    {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
    }

    free( buffer ); 
    return nil;
}
else
{
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, 1,
                                          keyPtr, kCCKeySizeAES128,
                                          ivPtr,
                                          [self bytes], dataLength,
                                          buffer, bufferSize, 
                                          &numBytesDecrypted );
    if( cryptStatus == kCCSuccess )
    {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
    }

    free( buffer );
    return nil;
}