NIST picks HQC as a backup post-quantum encryption algorithm
11 MARCH 2025, GAITHERSBURG
NIST announced that it had selected HQC (Hamming Quasi-Cyclic) as a fifth post-quantum algorithm and a backup for general encryption. HQC is a code-based key-encapsulation mechanism, meaning a method for two parties to agree a shared secret key, built on error-correcting codes. ML-KEM (FIPS 203), the main standard, rests on structured lattices instead. NIST's release says reviewers found HQC computationally heavier than ML-KEM but secure and clean in operation.
The reason for the choice is diversification. Dustin Moody, who heads NIST's post-quantum project, said NIST wants a backup standard based on a different mathematical approach than ML-KEM. If someone found a weakness in lattice constructions, organizations would then have an approved alternative with a different security basis.
NIST set out a timeline. It expected to publish a draft standard in about a year, follow that with a 90-day public comment period, and finalize the standard in 2027. NIST also told organizations not to wait: Moody said they should keep migrating to the standards finalized in 2024. HQC is not meant to replace ML-KEM as the recommended general choice.
The choice reaches vendors of key-establishment products, hardware security module makers, protocol designers and standards bodies that plan for algorithm-agility, along with federal agencies that will eventually run HQC alongside ML-KEM. As of 2 October 2026, NIST's standardization page records the 11 March 2025 HQC selection and refers readers to NIST IR 8545 for status. It does not mention a draft standard, a FIPS 207 designation or publication dates.
Why it matters. Executives should not pause ML-KEM migration to wait for HQC, because NIST said so directly. The backup matters for planning: organizations should expect products to need the ability to swap key-establishment algorithms (crypto agility) without rebuilding systems. Procurement teams should expect HQC to appear in vendor roadmaps once a standard is final, which NIST targets for 2027.