Post-quantum cryptography and the number 35

Cloudflare published a blog post in early April 2026 announcing accelerated post-quantum cryptography migration, targeting full PQC readiness by 2029. The framing implies quantum computers pose an imminent threat to current encryption.

The numbers tell a different story.

the state of factoring

The largest number factored by a quantum computer without classical pre-processing assistance is 35. That is 5 × 7. This was achieved using Shor's algorithm on a small number of physical qubits.

RSA-2048 requires factoring a 617-digit number. The gap between 35 and a 617-digit number is not a gap — it is seven orders of magnitude of unsolved engineering, physics, and error correction.

the qubit problem

Current quantum computers operate with physical qubits that have error rates around 0.1–1%. To run Shor's algorithm on RSA-2048, you would need approximately 4,000 logical qubits. Each logical qubit requires roughly 1,000–10,000 physical qubits for error correction using surface codes.

That means 4–40 million physical qubits operating coherently. The largest quantum computers today have approximately 1,200 physical qubits. The gap is not closing on any published timeline.

harvest now, decrypt later

The one legitimate concern is "harvest now, decrypt later" — adversaries collecting encrypted traffic today to decrypt it when quantum computers eventually arrive. This is real, but the timeline matters. Most harvested data loses value within 5–10 years. If quantum computers capable of breaking RSA-2048 are 15–25 years away (the consensus estimate among physicists, not marketing departments), the harvest window is mostly irrelevant.

what the migration actually is

Cloudflare's PQC migration is sound engineering practice — upgrading to algorithms that are quantum-resistant regardless of when quantum computers arrive. This is reasonable. What is not reasonable is the implicit urgency, the marketing timeline, and the suggestion that "Q-day" is approaching.

Q-day is not approaching. The number is still 35.