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Google announced a new Chrome program to make HTTPS certificate authentication resilient to future quantum attacks by evolving Certificate Transparency (CT) toward Merkle Tree Certificates (MTCs). The approach is designed to mitigate the risk that a sufficiently capable quantum computer running Shor’s algorithm could forge classical signatures used in today’s PKI/CT ecosystem (e.g., forging Signed Certificate Timestamps to make unlogged certificates appear valid). Rather than immediately adding post-quantum X.509 certificate chains into the Chrome Root Store, Google is pursuing MTCs through the IETF’s new PLANTS working group (PKI, Logs, And Tree Signatures), replacing heavyweight serialized signature chains with compact Merkle proofs of inclusion anchored by a CA-signed tree head.
Google’s design combines classical and post-quantum cryptography (including ML-DSA) so an attacker would need to break both to successfully forge proofs, while keeping handshake/CT authentication data small. Ars Technica reports Google is using “clever math” to keep MTC-related authentication artifacts roughly 64 bytes (similar to current CT proofs) despite post-quantum key and signature size growth, and that the system is already implemented in Chrome with Cloudflare enrolling roughly 1,000 TLS certificates to test MTC behavior; Cloudflare is currently generating the distributed ledger, with a plan for CAs to eventually assume that role.
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Google plans to launch a Chrome Quantum-resistant Root Store and program in Q3 2027 that supports only Merkle Tree Certificates, operating alongside the existing Chrome Root Program during transition.
As the second rollout phase, Google plans to bootstrap public Merkle Tree Certificates with qualified Certificate Transparency log operators, expanding the system beyond feasibility testing.
Google said Chrome expects to support post-quantum X.509 certificates for private PKIs later in 2026, while deferring such support for the public Chrome Root Store in favor of Merkle Tree Certificates.
TrustAsia Technologies filed what appears to be the first certificate authority application for Chrome’s Merkle Tree Certificate test root store in Chromium Issue 538260165. The filing signals that independent CAs are beginning to implement Google’s emerging MTC-based post-quantum web PKI architecture.
Google said the new quantum-resistant root store approach is already implemented in Chrome, combining classical and post-quantum protections to harden certificate proof mechanisms against future forgery.
The IETF formed the PKI, Logs, And Tree Signatures (PLANTS) working group to develop a standards-based approach for Merkle Tree Certificates and related post-quantum web PKI changes.
Google publicly announced a multi-year Chrome initiative to make HTTPS certificate authentication resilient to future quantum-computing threats by using Merkle Tree Certificates instead of embedding post-quantum cryptography directly into public X.509 chains.
Google began experimenting with Merkle Tree Certificates on real internet traffic with Cloudflare, using a fail-safe model backed by traditional X.509 certificates. Ars Technica reports Cloudflare enrolled about 1,000 TLS certificates in the test deployment.
Google states its planned quantum-resistant root store will complement the Chrome Root Store introduced in 2022, establishing the existing trust framework that the new program will extend rather than replace immediately.
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Let's Encrypt said it will use **Merkle Tree Certificates (MTCs)** as its preferred approach for post-quantum authentication on the public web, arguing that conventional post-quantum signatures such as `ML-DSA` would make standard TLS certificate chains too large for reliable internet-scale handshakes. The model batches certificate issuance under a single signed Merkle tree head and delivers compact inclusion proofs, reducing handshake overhead while making Certificate Transparency inherent to issuance. Let’s Encrypt said current subscribers do not need to take immediate action, but future ACME clients and related tooling will need updates as the ecosystem moves toward the new format. The move aligns Let’s Encrypt with broader work by **Google, Cloudflare, Chrome, DigiCert, and the IETF**, as browser and infrastructure vendors push for scalable post-quantum TLS ahead of government migration deadlines from the NSA, NIST, and the EU. Let’s Encrypt plans a staging environment for MTC issuance in late 2026 and a production-ready deployment in 2027, while continuing to track `ML-DSA` support for traditional X.509 use cases outside the browser ecosystem. It also said the more urgent near-term defense remains post-quantum encryption against harvest-now-decrypt-later threats, urging operators to enable hybrid key exchange such as: ```text X25519MLKEM768 ```
Jun 29, 2026
Cloudflare has added post-quantum authentication to **Authenticated Origin Pulls** and **Custom Origin Trust Store**, enabling customers to use **ML-DSA** signatures for Cloudflare-to-origin TLS and build fully post-quantum-secure mutual TLS on that link. The company said the protection is effective only if organizations also remove trust in classical authentication paths to avoid downgrade attacks, and positioned the release as a key step toward its stated goal of full post-quantum security by 2029. Cloudflare also noted that post-quantum authentication for browser-facing WebPKI traffic will follow a different approach based on **Merkle Tree Certificates**. The rollout comes amid broader industry acceleration toward quantum-safe security. Cloudflare Radar has been tracking worldwide post-quantum encryption adoption, while Microsoft said the timeline for quantum risk is shifting and urged faster migration planning. Cloudflare said the new capability required changes across its Go-based control plane and **Pingora Origin** data plane, and disclosed that a **BoringSSL** upgrade triggered a June 10, 2026 incident when stricter `KeyUsage` enforcement caused compatibility problems before the issue was patched and resolved.
Jul 29, 2026
Google said **Android 17** will begin a broad migration to post-quantum cryptography as part of a plan to harden the platform against future quantum attacks on public-key systems. The company is introducing quantum-resistant protections across core trust components, including **Android Verified Boot**, **Remote Attestation**, **KeyMint**, and **Android Keystore**, with support centered on the NIST-standardized `ML-DSA` algorithm. Google said the move is intended to build a quantum-resistant chain of trust spanning device boot, identity verification, and hardware-backed security services. Google also said **Google Play** will support hybrid app signing that combines classical and post-quantum signatures, and will begin generating quantum-safe `ML-DSA` signing keys for new apps while allowing existing apps to opt in. The company is targeting completion of its broader post-quantum migration by **2029**, citing the risk of **store-now-decrypt-later** attacks and warning that organizations should begin adopting NIST-developed PQC standards before fault-tolerant quantum computers can break current encryption. Google added that future Play updates are expected to support hybrid key upgrades and prompt developers to rotate signing keys every two years.
Jun 29, 2026