public class EncThenMacKey
This class is a simple holder for a pair of secret keys, one used for encryption and the other one for authentication.
Yet, it is also a type of AuthEncKey and for extension a type of Secret key. Therefore, it can be passed to the
init functions of classes implementing the SymmetricEnc interface. Since ScEncryptThenMac is a type of SymmetricEnc,
it needs a key of type SecretKey to be passed in its init functions, but also it has to make sure that two distinct
keys have been passed, one for encryption and one for authentication. This can be achieved using an instance of this class.
Cryptography and Computer Security Research Group Department of Computer Science Bar-Ilan University (Yael Ejgenberg)