International Association
for Cryptologic Research

Public data can be authenticated by obtaining from a trustworthy website with TLS. Private data, such as user profile, are usually restricted from public access. If a user wants to authenticate his private data (e.g., address) provided by a restricted website (e.g., user profile page of a utility company website) to a verifier, he cannot simply give his username and password to the verifier. DECO (CCS 2020) provides a solution for liberating these data without introducing undesirable trust assumption, nor requiring server-side modification. Their implementation is mainly based on TLS 1.2.

In this paper, we propose an optimized solution for TLS 1.3 websites. We tackle a number of open problems, including the support of X25519 key exchange in TLS 1.3, the design of round-optimal three-party key exchange, the architecture of two-party computation of TLS 1.3 key scheduling, and circuit design optimized for two-party computation. We test our implementation with real world website and show that our optimization is necessary to avoid timeout in TLS handshake.