For years, quantum computing has been framed as a future problem for cybersecurity but that’s exactly where it has stayed, sitting comfortably on a long-term roadmap. That framing is dangerously outdated.

The reality is that the quantum threat isn’t something organizations will wake up to one day. It’s already unfolding quietly in the background through what’s known as “harvest-now, decrypt-later” attacks. Adversaries are stealing encrypted data today, fully aware that once quantum capabilities mature, that data will be trivial to decrypt. The risk isn’t hypothetical, and it isn’t confined to the next decade. It’s already started.

Quantum computing will be the next major shockwave to hit cybersecurity, but its impact won’t arrive with a single, dramatic moment. It will surface gradually through exposed intellectual property, compromised national security data, and sensitive customer information that organizations believed was safely locked away. By the time encryption fails, the damage will already be done.

This is why boards need to stop thinking about quantum resilience as an encryption problem alone. The organizations that will weather the quantum hangover aren’t the ones chasing the strongest cryptographic algorithms; they’re the ones building resilience into every layer of their networks today.

What “Harvest-Now, Decrypt-Later” Really Looks Like

Unlike ransomware attacks that announce themselves loudly and demand immediate payment, harvest-now campaigns are deliberately patient. Attackers infiltrate networks, often through misconfigured or poorly monitored infrastructure, and quietly exfiltrate large volumes of encrypted data. There’s no urgency on their side, no need to monetize the breach today. The value comes later.

Who’s most at risk? Any organization that stores long-life sensitive data: government agencies, defense contractors, financial institutions, healthcare providers, and critical infrastructure operators. But increasingly, private-sector enterprises with valuable IP or customer data are just as attractive. If data needs to remain confidential for five, ten, or twenty years, it’s already a target.

The most dangerous misconception I see is the belief that “it’s encrypted, so it’s safe.” Encryption buys time, but time is exactly what attackers are willing to wait for.

Quantum Resilience Starts With Access Resilience

Post-quantum cryptography will be essential, but it won’t arrive overnight. Standards are still evolving, and large-scale implementation across complex environments will take years. In the meantime, organizations need to focus on something far more immediate: limiting access to the data in the first place.

This is where access resilience becomes critical. If attackers can’t move freely across your network, can’t exploit misconfigurations and vulnerabilities, and can’t reach your crown jewels, the value of any harvested data drops dramatically. In practice, that means shifting attention back to foundational security controls that are often overlooked.

I’ve seen firsthand how network misconfigurations can quietly enable hundreds of known vulnerabilities over time. These aren’t exotic zero-days; they’re basic issues such as exposed management interfaces, overly permissive routing rules and unpatched network devices, that attackers rely on to gain persistence and move laterally. Fixing these doesn’t require waiting for quantum-safe algorithms. It requires visibility and discipline.

Why Crypto-Agility Matters but Isn’t Enough on Its Own

Crypto-agility is the ability to swap out cryptographic algorithms quickly as standards change. It will be a defining capability in the quantum era. Organizations that hard-code encryption deep into legacy systems will struggle to adapt when those algorithms become obsolete.

But crypto-agility only solves part of the problem. If your network is flat, poorly segmented, and inconsistently configured, agile cryptography won’t stop attackers from accessing and harvesting data. Configuration assurance, strong segmentation, and real-time visibility into network posture matter first because they reduce exposure today, not years from now.

A Practical 90-Day Plan for Boards

Preparing for quantum doesn’t require boiling the ocean. Leaders can take meaningful action in the next 90 days by focusing on four concrete steps:

1. Map your crown jewels. Identify the data that must remain confidential long-term and understand where it lives, how it’s accessed, and who can reach it.
2. Audit network configurations. Validate that routers, switches, and firewalls are configured securely and consistently, and that changes are routinely monitored.
3. Segment aggressively. Limit lateral movement so that a single foothold doesn’t become enterprise-wide access.
4. Test recovery, not just prevention. Assume breaches will happen and rehearse how quickly critical systems can be restored and isolated.

These actions don’t depend on future quantum breakthroughs. They reduce risk immediately and lay the groundwork for a smoother transition to post-quantum cryptography when the time comes.

Budgeting for Quantum Without Panic Spending

One of the biggest mistakes organizations make is treating quantum readiness as a separate, future budget line item. In reality, most of the investment is needed now and should flow into improving existing security hygiene, better configuration management, stronger segmentation, and tools that provide assurance across complex networks.

Quantum doesn’t change the fundamentals of good security; it raises the cost of ignoring them. The organizations that succeed will be those that invest steadily in network resilience rather than reacting in a rush when encryption finally breaks.

The quantum hangover won’t arrive with a warning label. By the time it’s obvious, it will already be too late. The good news is that the steps needed to prepare are well within reach today if leaders are willing to look beyond algorithms and focus on the security foundations that truly keep data out of the wrong hands.