采用 PKCS7 填充的 ECB 模式下的 AES 加密

从 Apple 的 IV 文档，

如果使用 ECB 模式或选择了流密码算法，则忽略此参数。

func AESEncryption(key: String) -> String? {
        
        let keyData: NSData! = (key as NSString).data(using: String.Encoding.utf8.rawValue) as NSData!
        
        let data: NSData! = (self as NSString).data(using: String.Encoding.utf8.rawValue) as NSData!
        
        let cryptData    = NSMutableData(length: Int(data.length) + kCCBlockSizeAES128)!
        
        let keyLength              = size_t(kCCKeySizeAES128)
        let operation: CCOperation = UInt32(kCCEncrypt)
        let algoritm:  CCAlgorithm = UInt32(kCCAlgorithmAES128)
        let options:   CCOptions   = UInt32(kCCOptionECBMode + kCCOptionPKCS7Padding)
        
        var numBytesEncrypted :size_t = 0
        
        
        let cryptStatus = CCCrypt(operation,
                                  algoritm,
                                  options,
                                  keyData.bytes, keyLength,
                                  nil,
                                  data.bytes, data.length,
                                  cryptData.mutableBytes, cryptData.length,
                                  &numBytesEncrypted)
        
        if UInt32(cryptStatus) == UInt32(kCCSuccess) {
            cryptData.length = Int(numBytesEncrypted)
            
            var bytes = [UInt8](repeating: 0, count: cryptData.length)
            cryptData.getBytes(&bytes, length: cryptData.length)
            
            var hexString = ""
            for byte in bytes {
                hexString += String(format:"%02x", UInt8(byte))
            }
            
            return hexString
        }
        
        return nil
    }