Cryptology ePrint Archive: Report 2019/989

Substitution Attacks against Message Authentication

Marcel Armour and Bertram Poettering

Abstract: This work introduces Algorithm Substitution Attacks (ASAs) on message authentication schemes. In light of revelations concerning mass surveillance, ASAs were initially introduced by Bellare, Paterson and Rogaway as a novel attack class against the confidentiality of encryption schemes. Such an attack replaces one or more of the regular scheme algorithms with a subverted version that aims to reveal information to an adversary (engaged in mass surveillance), while remaining undetected by users. While most prior work focused on subverting encryption systems, we study options to subvert symmetric message authentication protocols. In particular we provide powerful generic attacks that apply e.g. to HMAC or Carter-Wegman based schemes, inducing only a negligible implementation overhead. As subverted authentication can act as an enabler for subverted encryption (software updates can be manipulated to include replacements of encryption routines), we consider attacks of the new class highly impactful and dangerous.

Category / Keywords: secret-key cryptography / Algorithm Substitution Attacks, Authentication, Mass Surveillance

Original Publication (with minor differences): IACR-FSE-2020

Date: received 30 Aug 2019, last revised 23 Sep 2019

Contact author: marcel armour 2017 at rhul ac uk

Available format(s): PDF | BibTeX Citation

Version: 20190923:113133 (All versions of this report)

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