Companies encrypt data, secure connections, use certificates, and sign software in line with current security standards. However, data that is secure today may not remain secure in 5 or 10 years.

If certain information needs to remain confidential for a long time, or if we know that a device installed today will still be operating in the next decade, it is worth looking at cryptography from the perspective of the entire lifecycle of data and systems, while also taking into account the continuing development of quantum technologies.

Today’s quantum computers are not yet capable of practically breaking widely used RSA or elliptic curve cryptography, but this may change in the near future. Standards designed to replace vulnerable algorithms have already been developed, and institutions responsible for cybersecurity are providing increasingly specific guidance on how to prepare for this transition.

It is therefore worth starting preparations before Q-Day — the point at which a quantum computer becomes capable of posing a real threat to the public-key cryptography used today. Organizations should already be determining where cryptography is used and whether they will be able to replace it efficiently when the need arises.

Why is post-quantum cryptography becoming important now?

The development of quantum computers is still surrounded by considerable uncertainty. There is no single parameter, such as the number of qubits, that would allow Q-Day to be predicted reliably, although a real threat could emerge even within two years.

There has been clear progress in areas required to build large and reliable quantum computers. One example is the work of the Google Quantum AI team on the Willow processor, published in Nature in December 2024. The researchers demonstrated significant progress in error correction, one of the basic requirements for performing long and reliable quantum computations. At the same time, researchers are producing increasingly precise estimates of the resources that future attacks on RSA or elliptic curve cryptography — two widely used forms of asymmetric cryptography — would require. Although such analyses still do not allow us to calculate the date of Q-Day, they help us better understand the scale of technology required to carry out a real attack.

From a business perspective, what appears more important at this point is that standards for algorithms designed to replace vulnerable solutions already exist. In 2024, the U.S. National Institute of Standards and Technology (NIST) published the first three post-quantum cryptography standards: ML-KEM for establishing a shared key, and ML-DSA and SLH-DSA for digital signatures. At the same time, NIST encouraged organizations to begin preparing for migration and emphasized that implementing the new standards in complex environments will take time.

The European Union has taken a similar approach. In June 2025, EU Member States adopted a coordinated roadmap for the transition to post-quantum cryptography. It calls for migration activities to begin by the end of 2026 and, for high-risk use cases, for the transition to new solutions to take place as soon as possible and no later than the end of 2030. It also identifies specific actions that should be taken, including:

• creating an inventory of cryptographic assets,
• assessing risk,
• mapping dependencies,
• ensuring systems can be updated,
• and gradually deploying new algorithms.

What could quantum computers actually change?

Not all modern cryptography is exposed to the risks associated with quantum computing to the same degree. The most important distinction for understanding the issue is between symmetric cryptography and asymmetric cryptography, also known as public-key cryptography.

• Symmetric cryptography uses the same secret key to encrypt and decrypt data. One of the most widely used algorithms of this type is AES (Advanced Encryption Standard), which is used, among other things, to protect files, databases, and data in transit. This type of cryptography is far less vulnerable to threats associated with quantum computers than asymmetric cryptography.

• Asymmetric cryptography (public-key cryptography) uses a pair of related keys: a public key and a private key. This makes it possible, among other things, to establish secure connections, authenticate users and systems, and create digital signatures. The most widely used solutions of this type include RSA and ECC (Elliptic Curve Cryptography).

These are the mechanisms that are most exposed. A sufficiently advanced quantum computer could use Shor’s algorithm to solve much more quickly the mathematical problems on which the security of RSA and ECC is based. In practice, this could make it possible to derive a private key from information that may be publicly available today, thereby undermining the security of mechanisms based on these algorithms.

The risks associated with quantum computers may arrive sooner than you think

One of the most important post-quantum risk scenarios is Harvest Now, Decrypt Later. The idea is simple: an attacker can intercept encrypted data today, even if they cannot currently read it, and return to it later when technology becomes available that can break the protections used.

The significance of such an attack depends primarily on how long the information retains its value. Some data becomes outdated quickly, while in other cases confidentiality needs to be maintained for years or even decades. This applies, among other things, to trade secrets, intellectual property, strategic financial information, medical records, and data related to critical infrastructure.

Digital signatures and certificates are also at risk

Asymmetric cryptography is used not only to protect communications, but also to confirm identities and verify that data or software has not been altered. Digital signatures and certificates are among the mechanisms used for this purpose: a signature helps confirm the origin and integrity of data or software, while a certificate helps verify the identity of a system or device.

One example of this use of digital signatures is code signing. A manufacturer can digitally sign software or an update so that a device or user can verify that it really comes from a trusted source and has not been modified along the way.

When migrating to post-quantum cryptography, securing communication alone will not be enough. If a digital signature still relies on an algorithm that is vulnerable to quantum attacks, that mechanism will also need to be replaced.

This is particularly important in OT and IoT environments, where devices often remain in use for many years. A system installed today in a factory, power plant, or other infrastructure facility may still be operating long after the rest of the environment has begun moving to new cryptographic mechanisms. Whether it can be updated will depend, among other things, on the hardware design, firmware, vendor support, and the availability of updates.

When assessing post-quantum risk, organizations therefore need to consider not only how long data must remain protected, but also how long the systems and devices using that cryptography will remain in operation. To assess the scale of future changes, an organization first needs to know where and how cryptography is currently being used.

Before you can change something, you need to know where it is being used

In a large environment, answering the seemingly simple question “Where do we use RSA and ECC?” can be much more difficult than it appears. Cryptography is used across almost the entire IT environment — from applications and operating systems to cloud services, devices, and OT environments. It also underpins certificates, digital signatures, and many software security processes. Some of these mechanisms are embedded within third-party products and services, which means an organization may not always have full visibility into which algorithms are being used.

The starting point for a transition to post-quantum cryptography should therefore be an up-to-date inventory of cryptographic assets. A simple list of algorithms, however, will say very little if the organization does not know where they are used, what role they perform, what they protect, and which other elements of the environment they depend on. It is also important to understand how long a given system will remain in use and whether it will be possible to update it in the future.

Tools that detect the algorithms, certificates, and keys in use and track changes across the environment can help collect and organize this information. This allows an organization not only to create a picture of the current state, but also to keep it up to date as the infrastructure evolves.

Will the organization be able to change its cryptography?

Just as important as knowing which cryptographic mechanisms are in use is whether the organization will be able to replace them safely when they no longer provide the required level of protection or when new standards emerge.

The ability to replace or adapt cryptographic mechanisms efficiently is known as crypto-agility. The goal is to ensure that changing an algorithm does not require months of searching for dependencies or cause major disruptions to system operations.

In the case of post-quantum migration, some changes will likely be introduced through subsequent versions of systems, libraries, and services. Vendors are already gradually adding support for new cryptographic mechanisms, but the availability of an update does not mean that an organization has actually migrated to the new solution. It first needs to know where the update is required, whether it has actually been deployed, and whether the infrastructure components that interact with the system are compatible with it. In a large environment, different systems will move to new mechanisms at different speeds, which means classical and post-quantum cryptography will coexist for some time.

Vendor roadmaps will also matter. For SaaS services, network devices, or hardware security modules, the ability to move to new algorithms may depend on when the manufacturer releases an appropriate software version and how long older products continue to receive support.

Not every part of the infrastructure will be easy to update. This applies in particular to older devices and some OT environments, where changing cryptography may be technically difficult or impossible. If modernization is not feasible, the risk needs to be reduced in other ways, for example through network segmentation, device isolation, and strict monitoring and control of communications.

Preparations should start today

Although the development of quantum computers may still seem like a distant issue, it is better not to leave preparations until the last moment. Post-quantum cryptography standards are already available, solutions exist for discovering and inventorying cryptographic assets, and support for new algorithms is gradually being introduced into more products and services.

Organizations should therefore already begin building an understanding of which cryptographic mechanisms they use, which of them will need to change, and whether those changes can be carried out safely. The sooner an organization gains this visibility, the greater the chance that migration to new standards will be a planned process rather than a reaction carried out under time pressure.

If you want to find out where cryptography is used in your organization and which areas may require changes in connection with PQC, talk to the 4Prime experts. We can help assess your current environment, identify key dependencies, and plan the next steps.