Abstract. We propose a novel approach for quantifying a system's resistance to unknown-message side-channel attacks. The approach is based on a measure of the secret information that an attacker can extract from a system from a given number of side-channel measurements. We provide an algorithm to compute this measure, and we use it to analyze the resistance of hardware implementations of cryptographic algorithms with respect to power and timing attacks. In particular, we show that messageblinding -the common countermeasure against timing attacks -reduces the rate at which information about the secret is leaked, but that the complete information is still eventually revealed. Finally, we compare information measures corresponding to unknown-message, known-message, and chosen-message attackers and show that they form a strict hierarchy.
For quantitative analysis of timing side channels, Köpf and Backes REF propose an approach for quantifying resistance to unknown-message side-channel attacks and use this approach to assess the resistance of cryptographic implementations against timing attacks.
Formally Bounding the Side-Channel Leakage in UnknownMessage Attacks
In Proc. ESORICS ’08 (to appear), LNCS
Computer Science