Secure Message Authentication in the Presence of Leakage and Faults

. Security against side-channels and faults is a must for the deployment of embedded cryptography. A wide body of research has investigated solutions to secure implementations against these attacks at diﬀerent abstraction levels. Yet, to a large extent, current solutions focus on one or the other threat. In this paper, we initiate a mode-level study of cryptographic primitives that can ensure security in a (new and practically-motivated) adversarial model combining leakage and faults. Our goal is to identify constructions that do not require a uniform protections of all their operations against both attack vectors. For this purpose, we ﬁrst introduce a versatile and intuitive model to capture leakage and faults. We then show that a MAC introduced at Asiacrypt 2021 natively enables a leveled implementation where only its underlying tweakable block cipher must be protected, as long as only its tag veriﬁcation can be faulted. We ﬁnally describe two approaches to amplify security in the case where also the tag generation can be faulted. One is based on iteration and requires the adversary to inject increasingly large faults to succeed. The other is based on randomness and allows provable security against diﬀerential faults.