International Association
for Cryptologic Research

The authentication encryption (AE) scheme based on the duplex construction can no be paralellized at the algorithmic level. To be competitive with some block cipher based modes like OCB (Offset CodeBook) or GCM (Galois Counter Mode), a scheme should allow parallel processing. In this note we show how parallel AE can be realized within the framework provided by the duplex construction. The first variant, pointed by the duplex designers, is a tree-like structure. Then we simplify the scheme replacing the final node by the bitwise xor operation and show that such a scheme has the same security level.