Paper 2018/1232 Original: eprint.iacr.org/2018/1232 ↗

Certificate Transparency Using Blockchain

Abstract

The security of web communication via the SSL/TLS protocols relies on safe distributions of public keys associated with web domains in the form of $\mathsf{X.509}$ certificates. Certificate authorities (CAs) are trusted third parties that issue these certificates. However, the CA ecosystem is fragile and prone to compromises. Starting with Google's Certificate Transparency project, a number of research works have recently looked at adding transparency for better CA accountability, effectively through public logs of all certificates issued by certification authorities, to augment the current $\mathsf{X.509}$ certificate validation process into SSL/TLS. In this paper, leveraging recent progress in blockchain technology, we propose a novel system, called $\mathsf{CTB} $, that makes it impossible for a CA to issue a certificate for a domain without obtaining consent from the domain owner. We further make progress to equip $\mathsf{CTB}$ with certificate revocation mechanism. We implement $\mathsf{CTB}$ using IBM's Hyperledger Fabric blockchain platform. $\mathsf{CTB}$'s smart contract, written in Go, is provided for complete reference.