SoK: Delegation and Revocation, the Missing Links in the Web's Chain of Trust
This work addresses security vulnerabilities in web PKI for domain owners and users, but it is incremental as it builds on existing research with a systematic analysis.
The paper tackles the problems of key revocation and delegation in the web's public-key infrastructure, analyzing solutions and proposing a framework to address latency, availability, and privacy issues, with a focus on combining short-lived delegated credentials with revocation systems.
The ability to quickly revoke a compromised key is critical to the security of any public-key infrastructure. Regrettably, most traditional certificate revocation schemes suffer from latency, availability, or privacy problems. These problems are exacerbated by the lack of a native delegation mechanism in TLS, which increasingly leads domain owners to engage in dangerous practices such as sharing their private keys with third parties. We analyze solutions that address the long-standing delegation and revocation shortcomings of the web PKI, with a focus on approaches that directly affect the chain of trust (i.e., the X.509 certification path). For this purpose, we propose a 19-criteria framework for characterizing revocation and delegation schemes. We also show that combining short-lived delegated credentials or proxy certificates with an appropriate revocation system would solve several pressing problems.