Authenticated Encryption Schemes

Authenticated encryption offers the combined security properties of an encryption scheme and a message authentication code: it protects both confidentiality and authenticity of data. Authenticated encryption schemes are also referred to as authenticated ciphers or authenticated encryption with associated data. Like pure encryption schemes, authenticated encryption schemes and their security notions were originally formalized in terms of probabilistic algorithms. The two security goals of authenticated encryption, confidentiality and authenticity, are also reflected in its design: an authenticated cipher needs to iterate a core processing step that, on the one hand, translates the plaintext to a ciphertext block by block and, on the other hand, updates an internal state to produce a final authentication tag for the entire message. More recent designs, such as the ciphers in the CAESAR portfolio, show that dedicated constructions can be very competitive both in terms of efficiency and in terms of simplicity.