Symmetric nonce respecting security model and the mem mode of operation

Abstract

The MEM mode is a nonce-based encryption mode of operation proposed by Chakraborty and Sarkar, which was claimed to be secure against symmetric nonce respecting adversaries. We first compare this security model with two similar models and then show that MEM is not secure under symmetric respecting attacks. One attack needs one decryption and one encryption queries, and the other only needs one encryption query.