Preparing for Q-Day

What It Covers

Cloudflare cryptography engineer Bas Vesterbahn joins host Kevin Ball to explain how quantum computers threaten public key cryptography via Shor's algorithm, why Q-Day timelines have compressed dramatically toward 2029, and what concrete steps software engineers must take now to migrate systems to post-quantum standards.

Key Questions Answered

• •Harvest-now-decrypt-later exposure: Over 65% of Cloudflare clients already use post-quantum key exchange (ML-KEM), protecting against adversaries recording encrypted TLS sessions today for future quantum decryption. Engineers running modern browsers get this protection automatically, but server-side certificate automation must be implemented now to cover the remaining gap before Q-Day arrives.
• •Post-quantum certificate deployment timeline: Chrome will begin accepting post-quantum certificate authorities in Q1 2027. Servers will need two simultaneous certificates — one classical RSA/ECC and one post-quantum — to maintain backward compatibility. Engineers should audit whether their application servers currently support multiple certificate slots, since many assume a single slot only.
• •Signature size performance impact: ML-DSA-44 post-quantum signatures measure 2.5 kilobytes versus 64 bytes for elliptic curve signatures. TLS handshakes typically send six signatures, adding roughly 15 kilobytes per connection. Since approximately half of QUIC connections transfer under 8 kilobytes total, engineers must audit latency-sensitive or bandwidth-constrained endpoints for degradation before enabling post-quantum authentication by default.
• •Quantum timeline compression: Required physical qubits to break RSA-2048 dropped from 200 million to roughly 1 million on superconducting hardware. A separate result using neutral-atom reconfigurable architectures shows P-256 elliptic curve keys crackable with only 10,000–20,000 physical qubits in approximately one month, making a 2030 cryptographically relevant quantum computer plausible rather than theoretical.
• •Migration prioritization framework: Rather than bottom-up key inventories, engineers should conduct top-down business continuity analysis — assuming a quantum computer exists today and mapping actual operational impact per system. Hard cases to surface immediately include JWT tokens in URLs, chunky HTTP headers, hardware-bound cryptography, bespoke protocols like WireGuard, and vendor dependencies with no clear upgrade roadmap.