DiStefano: decentralized infrastructure for sharing trusted encrypted facts and nothing more

We design DiStefano: an efficient, maliciously-secure framework for generating private commitments over TLS-encrypted web traffic, for a designated third-party. DiStefano provides many improvements over previous TLS commitment systems, including: a modular protocol specific to TLS 1.3, support for arbitrary verifiable claims over encrypted data, client browsing history privacy amongst pre-approved TLS servers, and various optimisations to ensure fast online performance of the TLS 1.3 session. We build a permissive open-source implementation of DiStefano integrated into the BoringSSL cryptographic library (used by Chromium-based Internet browsers). We show that DiStefano is practical in both LAN and WAN settings for committing to facts in arbitrary TLS traffic, requiring < 1 s and ≤ 5 KiB to execute the online phase.