Paper 2026/1068 Original: eprint.iacr.org/2026/1068 ↗

Self-Guarding Arbitrary Cryptographic Primitives and 2PC Protocols

Abstract

In IEEE CSF '18, Fischlin and Mazaheri introduced the notion of self-guarding cryptographic protocols as a countermeasure to algorithm substitution attacks. After a trusted initialization phase, a Self-Guarder wraps the user's cryptographic algorithm implementation and sanitizes it in a way that (1) prevents that an adversary can exploit the subverted implementation to exfiltrate user's data and (2) maintain the correctness of the genuine implementation. Whilst the proposed solutions in CSF '18 support a bounded number of executions before requiring a re-initialization phase, we show a universal self-guarder supporting an unbounded number of executions from a single trusted setup. Our self-guarder can be applied to any cryptographic primitive and any two-party computation protocol in the stand-alone setting with the aid of a verifiable-computation-enabling compiler.