fun encryptAES(cleartext: String, iv: ByteArray?, secret: SecretKeySpec): String {
            val cipher = Cipher.getInstance("AES/CBC/PKCS5Padding")
            cipher.init(Cipher.ENCRYPT_MODE, secret, if (iv == null) null else IvParameterSpec(iv))
            val ciphertext = cipher.doFinal(cleartext.toByteArray(charset("UTF-8")))
            return Base64.encodeToString(ciphertext, Base64.NO_WRAP)
        }