NIST Selects HQC as Fifth Algorithm for Post-Quantum Encryption: What It Means For You

Last year, the National Institute of Standards and Technology (NIST) finalized a set of post-quantum encryption standards designed to withstand attacks from future quantum computers. Now, NIST has chosen another algorithm, HQC, as a backup to ML-KEM, the primary encryption algorithm for protecting internet traffic and stored data. But what does this mean for organizations preparing for the post-quantum era? Let’s break it down.

Introduction to HQC

Last year, NIST standardized ML-KEM (Kyber) as the primary choice for post-quantum encryption due to its efficiency and strong security. Now, as a precautionary measure, NIST has selected HQC (Hamming Quasi-Cyclic) as a backup, ensuring continued protection if vulnerabilities in ML-KEM ever arise.

While ML-KEM remains the preferred algorithm, HQC provides an alternative, reinforcing the need for flexibility in encryption strategies. The key distinction between the two lies in their mathematical foundations; ML-KEM is based on structured lattices, whereas HQC relies on error-correcting codes, a well-established cryptographic approach. This diversity strengthens overall security, reducing reliance on a single encryption method.

HQC is not intended to replace ML-KEM but to serve as a contingency plan. Though it is slightly more resource-intensive, its robust security properties make it a viable long-term option. By diversifying encryption methods, NIST is ensuring organizations remain resilient against future quantum advancements.

How HQC Fits with Existing Algorithms

NIST’s post-quantum cryptography standardization process has resulted in a diverse set of algorithms, each designed to address different security needs. HQC and ML-KEM both function as key encapsulation mechanisms (KEMs), securing data in transit and at rest. However, they are built on distinct mathematical foundations, ensuring resilience in case vulnerabilities arise in one approach.

Beyond KEMs, NIST has also standardized digital signature algorithms such as CRYSTALS-Dilithium, FALCON, and SPHINCS+, which authenticate data and verify identities. Together, these encryption and authentication mechanisms form a comprehensive security framework for organizations preparing for post-quantum threats. The inclusion of HQC enhances this framework by providing redundancy and risk mitigation, ensuring encryption remains secure as cryptographic research evolves.

Rather than replacing ML-KEM, HQC complements it, creating a two-layered defense that reduces reliance on a single cryptographic approach:

• ML-KEM (Structured Lattices): Highly efficient and widely studied, making it the preferred choice for general encryption.
• HQC (Error-Correcting Codes): A long-established cryptographic method that serves as a strong alternative if lattice-based encryption ever becomes vulnerable.

Timeline and Next Steps

NIST plans to release a draft standard incorporating HQC in about a year, with a finalized version expected by 2027. In the meantime, organizations should continue migrating to the finalized post-quantum encryption standards published in 2024, including ML-KEM for general encryption and the digital signature algorithms in FIPS 204 and FIPS 205.

How This Impacts Organizations

If your organization is in the process of migrating to post-quantum cryptography, the selection of HQC doesn’t mean you need to change course.

• Continue migrating to ML-KEM as NIST finalizes this standard in 2024.
• Be aware of HQC as a backup option and stay updated on its standardization timeline (expected finalization in 2027).
• Prepare for a multi-layered cryptographic approach having diverse encryption mechanisms that ensure resilience against future threats.

Next Steps for Security Teams

As organizations prepare for the quantum era, security teams must take proactive measures to ensure a smooth and secure transition to post-quantum cryptography. Here are the key steps professionals should take:

• Review NIST’s Guidance on Post-Quantum Cryptography (PQC)

  Security teams should closely follow NIST’s recommendations, particularly for Key Encapsulation Mechanisms (KEMs) like ML-KEM and HQC, as well as digital signature algorithms such as CRYSTALS-Dilithium, FALCON, and SPHINCS+. Understanding the strengths, limitations, and best practices for each algorithm is crucial for effective implementation.

• Monitor HQC’s Standardization Process

  While ML-KEM is the primary post-quantum encryption algorithm, HQC has been selected as a backup. Security teams should stay updated on its development, testing phases, and anticipated finalization in 2027 to determine when and how it might fit into their cryptographic strategy.

• Begin Adopting Quantum-Resistant Encryption Now

  The quantum threat is not a distant possibility; it is a real and imminent challenge. Organizations should start transitioning to quantum-safe encryption before quantum computers become capable of breaking classical cryptographic algorithms. This includes conducting cryptographic inventories, identifying at-risk data, implementing hybrid cryptographic models, and ensuring systems are adaptable to future advancements.

How Encryption Consulting’s PQC Advisory Can Help

Navigating the transition to post-quantum cryptography requires careful planning, risk assessment, and expert guidance. At Encryption Consulting, we provide a structured approach to help organizations seamlessly integrate PQC into their security infrastructure.

• Validation of Scope and Approach: We assess your organization’s current encryption environment and validate the scope of your PQC implementation to ensure alignment with industry best practices.
• PQC Program Framework Development: Our team designs a tailored PQC framework, including projections for external consultants and internal resources needed for a successful migration.
• Comprehensive Assessment: We conduct in-depth evaluations of your on-premise, cloud, and SaaS environments, identifying vulnerabilities and providing strategic recommendations to mitigate quantum risks.
• Implementation Support: From program management estimates to internal team training, we provide the expertise needed to ensure a smooth and efficient transition to quantum-resistant algorithms.
• Compliance and Post-Implementation Validation: We help organizations align their PQC adoption with emerging regulatory standards and conduct rigorous post-deployment validation to confirm the effectiveness of the implementation.

Conclusion

NIST’s selection of HQC reinforces the importance of having backup options in cryptographic security. As organizations transition to quantum-resistant encryption, a diverse and adaptable approach will be key to staying protected.