Attack-Resilient TLS Certificate Transparency

Abstract

The security of Public-Key Infrastructure (PKI) for Internet-based communications has lately attracted researchers' attention because of Certification Authorities (CAs) crashes and consequent attacks. Google Certificate Transparency and subsequent log-based PKI proposals (e.g., AKI and ARPKI) have succeeded in making certificate-management processes more transparent, accountable, and verifiable. However, those proposals failed to solve the root CA generous delegation of trust to intermediate CAs, non-conformant certificate-issuance by them, and lack of rigorous authentication of domain ownership during certificate-issuance problems. This study presents Attack-Resilient TLS Certificate Transparency (ARCT) based on log servers to address these problems. ARCT enables root CA to enforce intermediate CAs to follow community standards through leveraging a log server at each root level. It also introduces a collaborative domain ownership verification method that deters false certificate-issuance and ensures that a set of CAs validates every certificate before any client will accept it. A certificate collectively approved by a set of CAs assures users that the certificate has been seen, and not instantly detected malicious, by a group of CAs. Finally, formal security and performance evaluations prove the reliability and effectiveness of ARCT.