Quantum-ready FN-DSA (FIPS 206) nears draft approval

Author: Joe Peck

NIST has submitted the draft standard for FN-DSA (FIPS 206), the FALCON-based digital signature scheme, moving it closer to formal adoption as part of the post-quantum cryptography (PQC) standardisation process.

FN-DSA was selected alongside ML-DSA and SLH-DSA for PQC standardisation, but its approval has taken longer due to mathematical complexity and refinements to its components. With the draft now submitted, the first release is imminent.

The draft will be published as an Initial Public Draft (IPD) for open review. While the timeline has not been finalised, it may coincide with the NIST PQC Standardisation Conference in September 2025.

Based on past schedules, the review period is expected to last around one year, with a final standard likely in late 2026 or early 2027.

Industry preparations

Companies such as DigiCert, a US-based digital security company, are preparing for FN-DSA’s rollout. To avoid confusion around naming and identifiers, DigiCert has stated it will not implement FN-DSA in production until the standard is finalised.

In the meantime, the company will make the IPD version available for experimentation through DigiCert Labs, which already hosts FALCON for testing. This will enable the wider community to trial the draft standard before formal approval.

Role in post-quantum cryptography

FN-DSA is seen as a special purpose scheme rather than a replacement for ML-DSA. Its smaller signature sizes could reduce certificate chain lengths, which is valuable in environments where efficiency is a priority.

However, due to the complexity of FALCON’s signing process, FN-DSA is less suited for frequently signed leaf certificates. Instead, it is expected to be more useful for root and intermediate certificates.

NIST has also signalled potential adjustments to signing and sampling methods, which could broaden FN-DSA’s applications once the draft specification is published.

The progress of FN-DSA marks another milestone in the move towards quantum-safe standards. Organisations are being encouraged to begin preparation now by testing draft algorithms, trialling implementations, and developing crypto-agility strategies to ensure a smooth transition as PQC standards are finalised.

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