Standardization of post-quantum cryptographic algorithms by NIST

With quantum computing rapidly advancing, traditional cryptographic algorithms face significant risks. Recognizing this emerging threat, the National Institute of Standards and Technology (NIST) launched a rigorous international process in 2016 to evaluate and standardize algorithms resilient against quantum attacks. This article provides an overview of the process, selected algorithms, and the corresponding Federal Information Processing Standards (FIPS).

1. History of the standardization process

In 2016, NIST began the international call for post-quantum cryptographic algorithms, receiving 69 submissions comprising key encapsulation mechanisms (KEMs) and digital signature algorithms. These submissions marked the beginning of an extensive multi-phase evaluation process involving cryptographers, security researchers, and government agencies worldwide.

2. Evaluation phases

The NIST process proceeded through four structured rounds:

• First Round (2017–2019): From 69 submissions, 26 algorithms advanced after initial evaluations on security and performance criteria.
• Second Round (2019–2020): NIST narrowed down the competition to 15 candidate algorithms after extensive security assessments and community feedback.
• Third Round (2020–2022): Four algorithms were selected for formal standardization:
  • CRYSTALS-ML-KEM — key encapsulation mechanism
  • CRYSTALS-ML-DSA — digital signature
  • FALCON — compact digital signature
  • SLH-DSA — stateless hash-based digital signature
• Fourth Round (2022–2024): Evaluation continued to diversify and identify additional KEM solutions, resulting in the selection of HQC.

3. Selected algorithms and FIPS standards

In 2024, NIST formally standardized three algorithms under new Federal Information Processing Standards:

• CRYSTALS-Kyber → FIPS 203 (ML-KEM)
• CRYSTALS-Dilithium → FIPS 204 (ML-DSA)
• SPHINCS+ → FIPS 205 (SLH-DSA)

FALCON is in final preparations for standardization as a fourth FIPS algorithm, covering high-performance digital signatures with compact key sizes.

4. Selection criteria

Algorithms underwent extensive evaluations based on the following criteria:

• Security: Robustness against classical and quantum cryptanalysis, including resistance to Shor's and Grover's algorithms
• Performance: Efficiency on classical computing hardware and embedded systems
• Flexibility: Suitability for diverse practical applications across industries
• Peer review: Community-driven cryptographic analysis and independent audits

5. Recent update: HQC algorithm

On March 11, 2025, NIST selected an additional KEM — HQC (Hamming Quasi-Cyclic) — to enhance the algorithm portfolio and provide greater diversity in standardized quantum-resistant solutions. HQC's code-based security assumptions differ fundamentally from the lattice-based approaches of ML-KEM, providing valuable cryptographic diversity.

6. Conclusion

The standardization of post-quantum cryptography by NIST marks a critical milestone in global cybersecurity, safeguarding digital communications against future quantum threats. Standards such as FIPS 203, FIPS 204, and FIPS 205 represent significant steps forward, enabling secure transitions to quantum-resistant cryptographic infrastructures. Organizations that begin migration today will be positioned ahead of regulatory deadlines and ahead of the quantum threat.

References

• NIST (2020). Status Report on the Second Round. Link
• NIST (2022). Status Report on the Third Round (NISTIR 8413). Link
• NIST (2024). Finalized PQC Standards Announcement. Link
• NIST (2025). Selection of Additional KEM Algorithm HQC (NIST IR 8545). Link
• NIST (2024). Approval of FIPS 203, 204, 205. Link