Securing infrastructure and services against the cryptographically relevant quantum computer of the future presents a major concern for the IT industry. Every encrypted connection will present a liability.
The nation-state adversaries and organized threat actors who keep harvesting encrypted traffic are betting that a future quantum computer will hand them decryption keys. This strategy turns post-quantum cryptography from an academic exercise into a hard migration deadline.
But the algorithms that defeat this threat carry a cost that most organizations haven't reckoned with. Quantum-resistant keys and signatures are dramatically larger than their classical counterparts.
Stapling these keys and signatures onto the public key infrastructure that the Internet already runs also presents a problem. It threatens to inflate every transport layer handshake while straining mobile and high-latency connections. Legacy load balancers could even break outright.
The Fight to Save the Plumbing of the Web
To help the IT industry take on this challenge, Google Cloud recently published a roadmap to achieve full post-quantum cryptography readiness by 2029. The roadmap confronts the cost trade-off head-on. The most consequential move isn't a bigger key size—but rather an entirely different architecture.
Instead of forcing post-quantum signatures into standard X.509 certificates, Google Cloud, along with Cloudflare, is experimenting with Merkle Tree Certificates—a structural rethink of how trust gets verified at scale. The pilot is now advancing through a working group within the Internet Engineering Task Force (IETF) toward a 2028 production target.
“The Merkle Tree Certificates (MTCs) do not force large post-quantum signatures into an infrastructure that wasn't designed for them,” notes Jason Soroko, a Senior Fellow at Sectigo, which is also contributing to the IETF workgroup. “Instead, they rethink how certificates are built and delivered for the post-quantum era.”
For security leaders, the Google Cloud roadmap is less a checklist than a signal. The fight to make quantum-safe cryptography usable is now a fight over the plumbing of the web itself.
The Clock Is Already Running
The "harvest now, decrypt later" paradigm used by threat actors seeks to intercept and store encrypted network traffic and data now, and then retroactively unlock it once quantum computers become operational. In essence, today's encrypted traffic is tomorrow's exposed data.
At the same time, post-quantum cryptography is shifting from a research topic to a compliance mandate, and the clock is already running. These developments have set the stakes: this is a migration problem, not a theoretical one.
While quantum-resistant algorithms solve confidentiality, they also balloon key and signature sizes. Bolted onto the current Public Key Infrastructure, the larger keys inflate bandwidth, processing, and storage.
“The Public key infrastructure (PKI) is ubiquitous in all our technology stacks,” Soroko points out. “Cloud applications, AI-driven workloads, and billions of connected devices all rely on fast, constant TLS handshakes. If post-quantum authentication slows those handshakes down, everyone feels it.”
Google Focuses on Three Risk Domains
Google Cloud has organized its roadmap around three risk domains:
- Store now and decrypt later mitigation
- Signature integrity
- Cryptographic agility
The Google Chrome browser will not carry post-quantum signatures in standard X.509 certificates. Instead, Google Cloud and Cloudflare are proposing the Merkle Tree Certificates as a structural alternative.
This is not a patch. The two companies are piloting the approach at production scale.
Working with the IETF PLANTS (PKI, Logs and Tree Signatures) group, Google Cloud and Cloudflare are reshaping the PKI standard industry-wide. Specifically, the Google Trust Service targets securing Merkle Tree Certificates by 2028. The shared responsibility model of this service will split infrastructure migration from customer-side updates.
What Practitioners Should Do Now
“The momentum behind this shift is real and measurable,” Soroko adds. “Browsers have signaled that the Merkle Tree Certificates are their preferred path for bringing post-quantum certificates to the public web, and feasibility experiments are already running against live Internet traffic.”
With the IETF targeting a 2028 production target and Google Cloud working towards full post-quantum cryptography readiness by 2029, there are key measures that enterprise security teams should implement in the interim 2-3 years:
- Inventory cryptographic assets before prioritizing a migration backlog.
- Update tooling and SDKs to negotiate post-quantum cryptography handshakes by default.
- Validate application behaviors against quantum-safe endpoints before mandates force the issue.
Taking these steps in the short term is critical, but the work of the IETF is sure to pay huge dividends. Sectigo believes the Merkle Tree Certificates represent the most promising route to post-quantum authentication that preserves the performance and scalability organizations depend on today.
“At the same time, we continue to track the broader post-quantum ecosystem, from NIST-standardized algorithms, such as ML-DSA, to evolving IETF specifications, browser roadmap decisions, and enterprise adoption requirements,” Soroko adds. “The full scope of what Merkle Tree Certificates can do is still coming into focus. What is clear is that organizations must have visibility, automation, and crypto agility to adapt as standards mature.”
