Algorithms
What is FN-DSA?
Also known as Falcon.
FFT-over-NTRU-Lattices Digital Signature Algorithm. NIST signature standard scheduled as FIPS 206 (draft). Two parameter sets (512, 1024). Smaller signatures than ML-DSA, used by QNSI for code-signing and TLS certificates where on-wire size matters.
Decision context
Why FN-DSA matters
FN-DSA addresses post-quantum signature use cases where compact signatures are valuable, but its implementation requirements and standardization status differ from finalized FIPS 204 and FIPS 205 paths. Those distinctions affect procurement language, assurance claims, interoperability, and production eligibility.
How to evaluate FN-DSA
Check the current NIST publication status, selected parameter set, implementation origin, floating-point or constant-time considerations, and protocol support. Do not describe FN-DSA as FIPS validated without the applicable finalized standard and implementation certificate. Keep experimental and production-approved paths visibly separate.
Algorithms
Algorithms evidence boundary
Algorithm names alone do not establish security or deployment readiness. Parameter set, implementation, key and signature sizes, execution boundary, validation status, and failure behaviour all matter. Buyers should distinguish a standardized primitive from a product path that has independently demonstrated that primitive in production.
Deep dive
FN-DSA on QNSI
NIST's fourth standardised PQC signature scheme, formally FN-DSA under FIPS 206 - the initial public draft is still pending as of mid-2026. Falcon's signatures are the most compact of the lattice-based PQC schemes, making it preferred for size-constrained transport.
For parameter sets, key and signature sizes, NIST ACVP conformance status, and when to use it, see the full FN-DSA algorithm reference.
FAQ
Common questions
What is FN-DSA?
FFT-over-NTRU-Lattices Digital Signature Algorithm. NIST signature standard scheduled as FIPS 206 (draft). Two parameter sets (512, 1024). Smaller signatures than ML-DSA, used by QNSI for code-signing and TLS certificates where on-wire size matters.
Why does FN-DSA matter?
FN-DSA addresses post-quantum signature use cases where compact signatures are valuable, but its implementation requirements and standardization status differ from finalized FIPS 204 and FIPS 205 paths. Those distinctions affect procurement language, assurance claims, interoperability, and production eligibility.
How should FN-DSA be evaluated?
Check the current NIST publication status, selected parameter set, implementation origin, floating-point or constant-time considerations, and protocol support. Do not describe FN-DSA as FIPS validated without the applicable finalized standard and implementation certificate. Keep experimental and production-approved paths visibly separate.
What is FN-DSA also known as?
FN-DSA is also known as Falcon. FFT-over-NTRU-Lattices Digital Signature Algorithm. NIST signature standard scheduled as FIPS 206 (draft). Two parameter sets (512, 1024). Smaller signatures than ML-DSA, used by QNSI for code-signing and TLS certificates where on-wire size matters.
More