Paper 2023/241 Original: eprint.iacr.org/2023/241 ↗

Lynx: Family of Lightweight Authenticated Encryption Schemes based on Tweakable Blockcipher

Abstract

The widespread deployment of low-power and handheld devices opens an opportunity to design lightweight authenticated encryption schemes. The schemes so proposed must also prove their resilience under various security notions. Romulus-N1 is an authenticated encryption scheme with associated data based on a tweakable blockcipher, a primary variant of Romulus-N family which is NIST (National Institute of Standards and Technology) lightweight cryptography competition finalist; provides beyond birthday bound security for integrity security in nonce respecting scenario but fails to provide the integrity security in nonce misuse and RUP (release of unverified plaintext) scenarios. In this paper, we propose lynx, a family with $14$ members of 1-pass and rate-1 lightweight authenticated encryption schemes with associated data based on a tweakable blockcipher, that provides birthday bound security for integrity security in both nonce respecting as well as nonce misuse and RUP scenarios and birthday bound security for privacy in nonce respecting scenario. For creating such a family of schemes we propose a family of function $\mathcal{F}$ that provides a total of $72$ cases out of which we show that only $14$ of them can be used for creating authenticated encryption schemes. We provide the implementation of one of the members of lynx family on six different hardware platforms and compare it with Romulus-N1. The comparison clearly shows that the lynx member outperforms Romulus-N1 on all the six platforms.