An AEAD Variant of the Grain Stream Cipher.

A new Grain stream cipher, denoted Grain-128AEAD is presented, with support for authenticated encryption with associated data. The cipher takes a 128-bit key and a 96-bit IV and produces a pseudo random sequence that is used for encryption and authentication of messages. The design is based on Grain-128a but introduces a few changes in order to increase the security and protect against recent cryptanalysis results. The MAC is 64 bits, as specified by the NIST requirements in their lightweight security standardization process.