Paper 2025/1686 Original: eprint.iacr.org/2025/1686 ↗

Honest Users Make Honest Mistakes: A Framework for Analysing eID Protocols

Abstract

Electronic identification (eID) protocols and federated identity management systems play an increasingly important role in our modern society, both on the internet through services from Google and others, and through the eIDAS regulation in Europe. A key feature of eID protocols is that humans are intimately involved in the protocol, often responsible for critical security steps. Traditional security analyses of such protocols typically assume flawless user behaviour, yet widespread real-world adoption makes user mistakes inevitable. We present a framework for analysing the security of eID protocols that can model users making mistakes. It is suitable for automated analysis with Tamarin and supports fine-grained corruption modelling of protocol actors. We demonstrate the framework's utility by describing and analysing common eID protocols based on passwords, mobile applications and authentication tokens, as well as by systematically evaluating the impact of various combinations of user mistakes on security.