This object selects the encryption algorithm, aes128 or aes256, used to protect traffic on this radio link, with the key length determined by the chosen algorithm. An admin picks aes256 for stronger encryption at the cost of slightly more processing overhead, or aes128 where a lighter-weight cipher suffices. Setting this to aes256(2), the default, means the paired rdEncryptKey object must then hold a 32-byte key.