For years, the threat quantum computing poses to encryption could be treated as a future problem. That position is becoming harder to sustain. The reason is not simply how quickly quantum computing develops. It is how long the data enterprises hold today needs to remain protected. In a "harvest now, decrypt later" attack, an adversary can collect encrypted information today and retain it in the hope of decrypting it in future, when sufficiently powerful quantum computers become available.

For organisations protecting information that must remain confidential for many years — from financial and healthcare records to intellectual property and government communications — post-quantum security is therefore becoming a present-day planning consideration. That shift is already reflected in global standards. The US National Institute of Standards and Technology (NIST) published its first three final post-quantum cryptography standards in 2024 and has encouraged organisations to begin transitioning towards quantum-resistant cryptography.¹ The question for enterprises is increasingly moving from "When should we think about this?" to "Where do we start?"

The good news is that enterprise leaders do not need to become cryptographers to understand the implications. At a high level, the public-key cryptography threatened by sufficiently capable quantum computers performs two important jobs. The first is establishing shared secrets for secure communications. This happens behind the scenes when systems establish encrypted connections. The second is digital signing — verifying that a user, device, application, software update or piece of data is genuinely what it claims to be.
 

NIST's first three standards address these functions:¹
 

• L-KEM establishes shared secrets that can be used to secure communications, making it relevant to areas such as secure network connections.
 

• ML-DSA provides digital signatures that can help authenticate identities, software and data.
 

• SLH-DSA provides another approach to digital signatures, based on different security assumptions, giving organisations and technology providers greater cryptographic diversity.

Other algorithms are progressing through NIST's standardisation process, including alternatives for both key establishment and digital signatures.² ³ That continuing evolution is important. Enterprises should not think of post-quantum migration as replacing today's algorithm with a single new one and considering the job finished.

Cryptographic standards will continue to develop, and vulnerabilities or new requirements may emerge over time. That makes the ability to change cryptography increasingly important.

Consider how deeply cryptography is embedded across a modern enterprise. It can sit inside applications, network connections, VPNs, certificates, cloud services, security appliances, hardware, APIs, software updates and connected devices. Now consider what happens if an algorithm used across thousands of those systems needs to be replaced. For many organisations, that could be a much bigger challenge than selecting the algorithm itself. This is where crypto agility becomes important: the ability to discover where cryptography is being used and update, replace or combine cryptographic approaches without redesigning the entire technology environment. It changes the post-quantum conversation.

Instead of asking only:

Which post-quantum algorithm should we adopt?

Enterprises should also ask:

How quickly could we change it if we needed to?

That is particularly relevant because post-quantum standardisation is still progressing. In May 2026, NIST advanced nine additional digital-signature candidates into a third round of evaluation, which is expected to run for approximately two years.² For enterprises, the lesson is straightforward: build for change rather than hard-coding today's choices into tomorrow's infrastructure.

A post-quantum migration does not have to begin with a wholesale infrastructure replacement. A more practical starting point is understanding where cryptography exists today, which data and systems have the longest security lifespans, and where future quantum threats would create the greatest business risk.

Several areas are likely to demand early attention.

• Network connections. Post-quantum cryptography can protect how shared secrets are established for secure communications, including connections across enterprise networks.¹

• VPNs and remote connectivity. Organisations with distributed operations need to consider how cryptographic changes will affect secure connections between offices, data centres, clouds and remote environments.

• Certificates and identity infrastructure. Digital certificates underpin trust across a vast range of enterprise systems. The IETF has standardised conventions for using ML-DSA in X.509 certificates and certificate revocation lists.⁴

• Software and firmware signing. Long-lived systems need to continue verifying that updates come from trusted sources. This is particularly important for infrastructure and devices expected to remain operational for many years.

• Long-lived sensitive data. Organisations should identify information that must remain confidential well into the future and assess whether "harvest now, decrypt later" presents a meaningful risk.

These assessments can help enterprises decide where migration should begin rather than attempting to change everything at once.

Post-Quantum Cryptography (PQC) is not the only technology being developed to address quantum-era security. Quantum Key Distribution (QKD) uses principles of quantum physics to distribute cryptographic keying material. Unlike PQC, it requires specialised infrastructure, which influences where and how it can be deployed. That means the enterprise conversation does not necessarily need to be framed as PQC versus QKD. The two can play different roles:
 

• PQC can provide scalable quantum-resistant protection using conventional computing and networking infrastructure, making it applicable across distributed enterprise environments.
  
  
• QKD can be applied to selected high-value connections where specialised infrastructure is practical and the sensitivity of the communications warrants it.

A hybrid approach can therefore enable enterprises to match different security technologies to different levels of risk and different parts of their network.

This is where the challenge moves beyond cryptography. An organisation may understand the emerging standards and still face a much harder question: how does it apply quantum-resistant protection consistently across data centres, branch offices, cloud environments, remote locations and international operations?

Singtel's Hybrid Quantum-Safe Network (QSN) is designed to address this infrastructure challenge. Launched as Southeast Asia's first Hybrid Quantum-Safe Network, it brings PQC and QKD together within a managed network architecture.⁵ ⁶

The hybrid approach enables enterprises to apply PQC across distributed and cloud environments while using QKD for selected communications where specialised quantum infrastructure is appropriate.⁵ ⁶ Rather than requiring organisations to approach quantum-safe security as an isolated infrastructure project, Hybrid QSN is designed to integrate quantum-safe capabilities into existing enterprise network and cybersecurity environments.⁵

Singtel's QSN also supports encryption across OSI Layers 1, 2 and 3, as well as MPLS, giving organisations flexibility in how quantum-safe protection is introduced according to their existing architecture and security requirements.⁵ For organisations that want to understand how these technologies would operate in their own environments before moving towards wider deployment,

Singtel also provides a three-phase pilot programme covering exploration workshops, integration testbeds and operational trials.⁵

Preparing for the post-quantum era does not mean replacing every cryptographic system tomorrow. It means understanding where the risks are and ensuring today's architecture does not limit tomorrow's choices.

Enterprise technology and security leaders can start with five questions:
 

1. Where is public-key cryptography used across our organisation today?
   
   
2. Which data needs to remain confidential for the longest period?
   
   
3. Which systems, devices and network connections would be hardest to migrate?
   
   
4. Can our existing security infrastructure support new or hybrid cryptographic approaches?
   
   
5. How quickly could we replace an algorithm if standards or threats changed?
    

The first post-quantum standards are already here. More will follow. For enterprises, the objective should not be to predict exactly which cryptographic algorithm will dominate ten years from now. It should be to build an infrastructure capable of adapting whichever way the standards evolve. That is what turns post-quantum readiness from a cryptography project into a resilience strategy.

Explore how Singtel's Hybrid Quantum-Safe Network can help your organisation build a practical path towards post-quantum readiness.