Paper 2019/724

Breaking Tweakable Enciphering Schemes using Simon's Algorithm

Sebati Ghosh and Palash Sarkar

Abstract

The threat of the possible advent of quantum computers has motivated the cryptographic community to search for quantum safe solutions. There have been some works in past few years showing the vulnerability of symmetric key crypto-systems in the quantum setting. Among these the works by Kuwakado et al. and Kaplan et al. use the quantum period finding procedure called Simon’s algorithm to attack several symmetric crypto-systems. In this work, we use Simon’s algorithm to break six tweakable enciphering schemes (TESs) in the quantum setting. These are CMC, EME, XCB, TET, AEZ and FAST. All of them have usual proofs of security in the classical sense. A version of EME and a version of XCB are IEEE standardised TESs.