Analysis and design of authenticated ciphers
Date of Issue2016
School of Physical and Mathematical Sciences
An authenticated cipher is a symmetric key cryptographic primitive which protects the confidentiality, integrity and authenticity of the data. It is an integration of the existing symmetric key primitives such as block ciphers, stream ciphers and hash functions, and attracts a lot of research interests in recent years, especially after the announcement of the CAESAR competition. In this thesis, we study the analysis and designs of the authenticated ciphers. We begin with an introduction to symmetric key cryptography and authenticated ciphers followed by discussing on the typical methods used in the cryptanalysis and design of authenticated ciphers. Then, several concrete case studies in analyzing the authenticated ciphers are presented. We apply differential-linear cryptanalysis to recover the internal state of ICEPOLE. Differential IV cryptanalysis is used to attack the initialization of the 128-EEA3/128-EIA3 stream cipher ZUC. By exploiting the leaked state from the keystreams, we present a forgery attack on ALE. By exploiting the parameter settings, we present distinguishing and forgery attacks against the authenticated encryption scheme COFFE. We provide a collision attack to break the authentication claim for the authenticated encryption mode IOC. For the design of authenticated ciphers, we propose two schemes, JAMBU and MORUS fulfilling various features. JAMBU is a lightweight authenticated encryption mode which provides an intermediate level of nonce misuse resistance. MORUS is a nonce-based authenticated cipher which is targeted for high performance in both software and hardware.