2029 and counting. Does Google’s Q-Day deadline highlight gaps in cybersecurity?

Last month Google set a 2029 deadline to complete its shift to post-quantum cryptography, warning that today’s encryption is already exposed to “harvest now, decrypt later” attacks. The company says the timeline reflects progress in quantum computing and a need to move before existing standards fail, aligning its approach with work led by NIST, the US science and tech standards body.

Putting a date on the transition, however, does not make it straightforward. Swapping out algorithms is one part of the job. Untangling the systems that rely on them, such as identity systems, key management, hardware trust, and the sprawl of certificates across modern infrastructure, is another. The risk is that post-quantum security is still being treated as a cryptography upgrade, when in practice it looks closer to a rebuild of the security stack.

And yet there is an increasing sense of urgency. As Philip Intallura, head of quantum at HSBC, says in a LinkedIn post (from the Quantum Australia event in Adelaide), when it comes to quantum security, it’s now undeniable. “CISOs are waking up. Boards are waking up. The penny has dropped that the urgency around quantum security is not a future problem, it’s a transformation programme that needs to start today.”

“If the UK transitions successfully that isn’t the whole story. We all use websites and resources from all over the world all the time, and share our data with companies from all over the world on a daily basis.”

Chloe Martindale, University of Bristol

The reason for this is that it’s not a standard cybersecurity upgrade. As Chloe Martindale, senior lecturer in cryptography at the University of Bristol says, post-quantum security may begin as a cryptography problem, but it does not end there.

“Changing systems that are currently secure to post-quantum secure is a problem that first has to be solved as a cryptography problem,” she says. “But this step is quite advanced and the challenges remaining are engineering, sociological, and political.”

Those challenges extend beyond national borders. Even if organisations in the UK move quickly, they remain dependent on global systems, services, and suppliers.

“If the UK transitions successfully that isn’t the whole story,” Martindale says. “We all use websites and resources from all over the world all the time, and share our data with companies from all over the world on a daily basis.”

Many systems are not secure today, regardless of the algorithms they use, and the gap between theory and practice shows up quickly inside organisations.

Jason Soroko, fellow at Sectigo, argues that while quantum computing weakens the mathematical foundations of today’s cryptography, it leaves much of the operational reality untouched.

“If an organisation could not track its RSA certificates, automate renewal, or enforce key protection policies before, it will fail in exactly the same ways with ML-DSA and ML-KEM,” he says.

The problem, in his view, is not just the choice of algorithm, but visibility.

“You cannot migrate what you cannot see.”

Most organisations, he argues, do not have a clear inventory of their cryptographic assets – where keys are stored, which systems depend on them, or who is responsible for managing them. Without that, the shift to post-quantum cryptography risks becoming a technical upgrade applied to systems that are already poorly understood.

Increasing risks

If post-quantum cryptography is forcing organisations to rethink their security foundations, advances in AI are raising the stakes further.

Anthropic’s Mythos model – an advanced AI system designed to identify previously unknown vulnerabilities – has added a new dimension to the problem. According to the company, the model is capable of uncovering “zero-day” flaws across major operating systems and browsers, exposing weaknesses that organisations may not even know exist.

That cuts directly across the assumptions behind post-quantum transition planning. For Martindale, the issue is not just future cryptographic risk, but the state of systems today.

“There are already huge numbers of systems with cybersecurity gaps, and for those making them post-quantum won’t change that by itself,” she says.

Tools capable of systematically identifying those gaps only increase the urgency. As Soroko argues, the challenge is often not the absence of security controls, but the lack of visibility and ownership around them.

In that context, post-quantum cryptography addresses one class of future threat, while systems like Mythos expose the weaknesses that already exist. And there are plenty.  As the UK government’s cybersecurity breaches survey shows, attacks remain common, while many organisations still fall short on basic practices such as patching, access control, and incident response.

The transition to post-quantum cryptography sits on top of that. It is not a clean upgrade. It is another layer added to systems that are already under considerable strain.

But for Martindale, this transition also opens a window.

“There is always a risk,” of repeating past mistakes, she says. “But there may actually be an opportunity in this transition effort to fix existing broken security systems.”

That depends on more than adopting new standards or meeting deadlines. It comes down to whether organisations understand the systems they are trying to secure, and whether they deal with the weaknesses that have been left in place.