Mind the Gap: Policy vs Reality in Post-Quantum TLS Deployment#

Authors: Nimesha Wickramasinghe (UNSW), Frank Li (Georgia Tech), Sanjay Jha (UNSW), Arash Shaghaghi (UNSW)

• Why: If you own or influence TLS-terminated services, the PQC migration is now an operational question, not a planning exercise. This paper tells you where the Internet actually is versus where government roadmaps say it should be — useful both for your own rollout sequencing and for evaluating vendor readiness claims.
• What: Three measurement rounds (July 2025–March 2026) covering one million public HTTPS endpoints, with over two billion TLS 1.3 handshakes from 11 distributed vantage points. Key findings: every observed post-quantum negotiation converged on the same hybrid — X25519MLKEM768 — but there is no verified deployment of post-quantum signature algorithms for authentication; hybrid adoption is concentrated in managed infrastructure providers; country/sector deployment does not track published transition timelines; and — counter to earlier experimental studies — hybrid key exchange showed no meaningful latency penalty in Internet settings. (from abstract only)
• How: Large-scale active TLS handshake measurement characterizing cryptographic negotiation behavior, cross-referenced against endpoint attribution (provider, country, sector) and against a survey of published PQC transition policies.
• Where applicable: Public-facing HTTPS broadly. The latency finding is calibrated to Internet RTT regimes — it does not tell you the handshake cost inside a datacenter fabric, so don't extrapolate it to internal service-to-service TLS.