ZLR

Abstract

Online authenticated encryption has been considered of practical relevance in lightweight environments due to low latency and constant memory usage. In this paper, we propose a new tweakable block cipher-based online authenticated encryption scheme, dubbed ZLR and its domain separation variant, dubbed DS-ZLR. ZLR and DS-ZLR follow the Encrypt-Mix-Encrypt paradigm. However, on the contrast to existing schemes using the same paradigm such as ELmE or CoLM, ZLR and DS-ZLR enjoy n-bit security by introducing larger internal states and maintaining them by an efficient ZHash algorithm. In this way, ZLR and DS-ZLR process 2n-bit blocks with only one primitive call for hashing and two primitive calls for encryption and decryption. As a result, ZLR and DS-ZLR efficiently support parallel computation with rate 2/3, enjoying online nonce-misuse resistance.