Cloudflare plans to issue quantum-proof TLS certificates, positioning itself as one of the first certificate authorities to offer cryptography designed to withstand attacks from quantum computers. The company targets Q1 2027 for initial production Merkle Tree Certificate issuance.
The initiative amounts to a fundamental overhaul of WebPKI—the public key infrastructure underpinning the web. Today's system relies on a chain of quantum-vulnerable signatures to verify certificate authenticity. Cloudflare aims to secure that chain against future threats.
The company will acquire a trusted certificate root from CA GlobalSign to enable millions of websites to adopt post-quantum certificates with minimal operational friction and no performance overhead. It will offer both traditional and post-quantum hybrid certificates free to all users.
The core technical challenge: quantum-resistant signatures must remain compact enough for web requests and certificate transparency logs. Standard post-quantum X.509 certificates would bloat TLS handshake data by roughly 40 times—enough to degrade internet functionality at scale.
Google introduced a solution in February using Merkle Trees, hierarchical data structures that verify large information sets using only a fraction of their content. Cloudflare and Google have tested the design in limited pilots. Merkle Trees compress the TLS handshake to approximately 40 kilobytes, comparable to current levels, replacing resource-intensive quantum-resistant signature chains with compact Merkle Tree proofs.
"We are not issuing certificates yet, and it will be a little while before we do," said Steve Goldsmith, Cloudflare. "What we are doing is committing to the work in public, sharing the milestones as they land, and telling you exactly what we are building while working with the root programs and other members of the WebPKI community."
Securing WebPKI against quantum attacks requires architectural changes beyond algorithm swaps. The transition will span years and demand coordination across operating systems, browsers, certificate authorities, and infrastructure providers.
