FINDING · EVALUATION
None of the six surveyed deployed protocols — TLS 1.3, QUIC v1, WireGuard, Shadowsocks 2022, obfs4, and Tor — provides the full set of BiFEP security properties (exact shaping, delivery, protocol-state integrity, private half-close, and cross-direction isolation) at the specification level.
From 2026-chen-closing-loop-bidirectional — Closing the Loop: Bidirectional Fully Encrypted Protocols · §I (abstract contribution bullet); §VIII-G (referenced protocol comparison) · 2026 · arXiv preprint
Implications
- Current production obfuscation tools (obfs4, Shadowsocks 2022) lack at least one BiFEP property — most likely cross-direction isolation or private half-close — creating detectable side channels that should be closed before deploying in high-risk censor environments.
- Adopt the BiFEP wrapper-layer design (authenticated DATA/DUMMY/FIN framing over an inner FEP) to cover gaps that none of the surveyed protocols currently address.
Tags
Extracted by claude-sonnet-4-6 — review before relying.