gistfile1.m

static __attribute__((always_inline)) CCCryptorStatus AES128Run(CCOperation operation, NSData *inData, NSData *key, NSData *__autoreleasing *outData) {
    CCCryptorStatus status = kCCParamError;

    if (outData != NULL) {
        CCCryptorRef cryptor = NULL;

        //correct key length
        NSMutableData *correctedKey = [key mutableCopy];
        if ([key length] <= kCCKeySizeAES128) {
            [correctedKey setLength:kCCKeySizeAES128];
        }
        else if ([key length] <= kCCKeySizeAES192) {
            [correctedKey setLength:kCCKeySizeAES192];
        }
        else {
            [correctedKey setLength:kCCKeySizeAES256];
        }
#if !__has_feature(objc_arc)
        [correctedKey autorelease];
#endif
        
        status = CCCryptorCreate(operation, kCCAlgorithmAES128, kCCOptionPKCS7Padding, [correctedKey bytes], [correctedKey length], NULL, &cryptor);

        if (status == kCCSuccess) {
            size_t length = CCCryptorGetOutputLength(cryptor, [inData length], true);
            NSMutableData *result = [NSMutableData dataWithLength:length];
            size_t updateLength;
            status = CCCryptorUpdate(cryptor, [inData bytes], [inData length], [result mutableBytes], [result length], &updateLength);
            if (status == kCCSuccess) {
                char *finalDataPointer = (char *)[result mutableBytes] + updateLength;
                size_t remainingLength = [result length] - updateLength;
                size_t finalLength;
                status = CCCryptorFinal(cryptor, finalDataPointer, remainingLength, &finalLength);
                [result setLength:updateLength + finalLength];
            }
            *outData = status == kCCSuccess ? [NSData dataWithData:result] : nil;
        }

        CCCryptorRelease(cryptor);
    }

    return status;
}