Authenticated Encryption Based on Finite Automata Cryptosystems

We present a new Authenticated Encryption (AE) scheme based on finite automata using the method Encrypt-then-MAC. The scheme is constructed from two cryptographic primitives, a symmetric encryption scheme based on finite automata known as FASKC and a Message Authentication Code (MAC) constructed from a finite automaton. The paper shows how the scheme works and how to construct a MAC from a finite automaton using a boolean function with good cryptographic properties. Due to the construction method and the assumption that the symmetric encryption scheme is secure under Chosen Plaintext Attack (CPA), it is shown that the MAC is unforgeable under Chosen Message Attack (UF-CMA) making the scheme secure under Chosen Ciphertext Attack (CCA).