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.