International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Formally Bounding the Side-Channel Leakage in Unknown-Message Attacks

Michael Backes
Boris Köpf
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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 message-blinding -- 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.
  title={Formally Bounding the Side-Channel Leakage in Unknown-Message Attacks},
  booktitle={IACR Eprint archive},
  keywords={Side-Channel Attacks, Formal Verification},
  note={This is an extended version of the ESORICS '08 paper 14104 received 10 Apr 2008, last revised 13 Aug 2008},
  author={Michael Backes and Boris Köpf},