Chrome tests Merkle Tree Certificates to future proof TLS

Chrome has unveiled a plan to shield HTTPS connections from the future threat of quantum computers by redesigning how certificates work, focusing on Merkle Tree Certificates (MTCs) rather than enlarging existing X.509 root store certificates. According to Infosecurity Magazine, the effort is being developed within the IETF PLANTS group, which stands for PKI, Logs and Tree Signatures, to tackle the quantum-resistant cryptography hurdles that increase TLS data sizes.

Chrome has begun testing MTCs on live traffic and outlined a three-phase rollout, with Phase 1 currently underway and a feasibility study conducted with Cloudflare, pairing each MTC-backed connection with a traditional X.509 certificate as a fail-safe. Phase 2 is scheduled for the first quarter of 2027 and will involve selected Certificate Transparency log operators to help bootstrap public MTC deployment, followed by Phase 3 in the third quarter of 2027 to introduce the Chrome Quantum-resistant Root Store.

The programme aims to modernise certificate governance while allowing continued support for existing authorities and private PKIs, as Chrome says it builds infrastructure for quantum-resistant HTTPS.