Paper 2019/989

Substitution Attacks against Message Authentication

Marcel Armour and Bertram Poettering


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.

Available format(s)
Secret-key cryptography
Publication info
A minor revision of an IACR publication in FSE 2020
Algorithm Substitution AttacksAuthenticationMass Surveillance
Contact author(s)
marcel armour 2017 @ rhul ac uk
2019-09-23: revised
2019-09-02: received
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Short URL
Creative Commons Attribution


      author = {Marcel Armour and Bertram Poettering},
      title = {Substitution Attacks against Message Authentication},
      howpublished = {Cryptology ePrint Archive, Paper 2019/989},
      year = {2019},
      doi = {10.13154/tosc.v2019.i3.152-168},
      note = {\url{}},
      url = {}
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