The quantum train – Sixth station: the final boarding call

When a train is about to leave a station, an announcement always sounds a few moments before the doors close. Travelers are invited to board one last time. At that instant, the train is still motionless, but everyone understands that the time available is no longer the same. Those already seated carry on reading or looking out the window. Those still hesitating suddenly realize that a few more minutes would have made all the difference.

The transition to quantum computing has a comparable characteristic. For several years, discussions have focused mainly on when quantum computers will reach sufficient power to call certain cryptographic mechanisms into question. That question remains important, but it often obscures a far more decisive element: by the time that deadline becomes obvious, part of the work should already have been done.

The reason is relatively simple. Not all information has the same lifespan. Some data quickly loses its relevance, while other data retains strategic value for several decades. Medical records, certain industrial secrets, research work, plans for critical infrastructure, or information related to national security must sometimes remain confidential well beyond the lifespan of the technologies that protect them today.

This reality gives rise to a scenario that cybersecurity specialists have been describing for several years: encrypted information can be intercepted and stored right now in the hope that it will become readable once computing capabilities have evolved sufficiently. This approach, often summed up by the expression “harvest now, decrypt later,” is a reminder that the value of a piece of data depends not only on its content, but also on how long it must remain protected.

For many organizations, this line of thinking represents a change of perspective. Cybersecurity has long consisted of protecting systems against immediate threats. Quantum computing now requires a much broader time dimension to be taken into account. It is no longer enough to ask whether a piece of information is secure today; one must also ask whether the mechanisms protecting it will remain suitable for the entire period during which that information retains its value.

This evolution explains why migrating to post-quantum cryptography cannot be reduced to a simple software update. Before replacing an encryption algorithm, an organization will need to know where it is used, which systems depend on it, which applications communicate with one another, and which partners will have to evolve at the same pace. In many companies, this inventory exists only partially. Some applications still rely on legacy technologies, sometimes developed by vendors that no longer even exist. Others are so tightly integrated into operations that it becomes difficult to gauge the impacts without an in-depth analysis.

The challenge will therefore not be technological alone. It will also be organizational. Companies that have taken the time to map their assets, document their dependencies, and classify their information according to its level of sensitivity will be able to plan their transition gradually. The others risk discovering that the difficulty lies not in choosing a new technology, but in understanding their own digital environment.

This difference is fundamental. A successful migration rarely calls for hasty decisions. On the contrary, it rests on methodical preparation, testing, validation, and coordination among many stakeholders. Yet all these steps take time. Time that can no longer be recovered once the new requirements become unavoidable.

At the risk of repeating ourselves, Quantum Beyond is convinced that preparation is never a matter of prediction. No one can state with certainty the precise moment when certain quantum capabilities will reach full commercial maturity. Every organization is, however, able to assess the value of its information assets, understand their dependencies, and estimate how long they will need to remain protected. It is this reflection that will make it possible to approach the next stage with confidence.

The final boarding call is never announced as the train pulls away from the station. It is announced while it is still possible to board. The whole difficulty lies in recognizing that moment before it is too late.