Chrome unveils 3-phase quantum-resistant HTTPS upgrade with Merkle Tree Certificates
Merkle Tree Certificates could reshape Chrome’s HTTPS security model.
Google has outlined a plan to strengthen Chrome’s HTTPS security against future quantum-computing threats. Rather than expanding traditional X.509 certificate chains in Chrome with post-quantum cryptography, the company is developing a new model based on Merkle Tree Certificates (MTCs).
The proposal from the PLANTS working group seeks to modernise the web public key infrastructure. Under the MTC model, a Certification Authority signs a single ‘Tree Head’ covering many certificates. Browsers receive a lightweight proof instead of a full certificate chain.
Google said this structure reduces authentication data exchanged during TLS handshakes while supporting post-quantum algorithms. By decoupling cryptographic strength from certificate size, the approach seeks to preserve performance as stronger security standards are adopted.
The company is already testing MTCs with real internet traffic. Phase one involves feasibility studies with Cloudflare, while phase two, in early 2027, will invite selected Certificate Transparency log operators to support initial public deployment.
By the third quarter of 2027, Google plans to establish requirements for onboarding certificate authorities to the quantum-resistant Chrome Root Store, which exclusively supports MTCs. The company described the initiative as foundational to maintaining long-term web security resilience.
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