HQC is a key encapsulation mechanism NIST selected on 11 March 2025 for standardization. It will be the second post-quantum KEM after ML-KEM. You cannot standardize your systems on it yet, because the standard was still being drafted when NIST announced it, and you do not need to wait for it.
What NIST announced
After the fourth round of its PQC process, NIST announced that HQC was selected. NIST IR 8545 explains the evaluation, including why HQC was chosen over BIKE and why Classic McEliece was not selected. NIST said it would draft a standard for HQC, take public comment, and expect a final version roughly two years after the announcement.
NIST's PQC project page as fetched in October 2026 repeats that HQC is selected for ongoing standardization and gives no further dates. Check that page for the current status before you cite a date.
Why a second KEM is useful
ML-KEM, from FIPS 203, is built on lattice problems. A cryptosystem with different mathematical foundations gives the ecosystem a fallback if a serious attack on the lattice approach ever appears. That framing is an interpretation. NIST's announcement says HQC will be the second PQC KEM and does not itself call it a backup.
Diversity of assumptions is a normal engineering principle. You would not want every lock in a building to open with the same key.
What to do about it today
Very little, and that is the point.
- Use ML-KEM, ideally in a hybrid, for new key establishment work. It is final and standardized.
- Make sure your protocol and code can add a new KEM later. This is crypto agility: algorithm identifiers in config, not hard coded in business logic.
- Record in your inventory where a KEM is chosen, so a second one can be slotted in.
- Do not pick HQC for production before there is a final standard and library support.
A note on timelines
Standards timelines slip. A "roughly two years" estimate from March 2025 is a planning hint, not a promise. If you have a procurement or audit date that depends on HQC, ask the vendor in writing what they plan and when.
Quick check
Should I wait for HQC before migrating?
No. ML-KEM is a final NIST standard and NIST's guidance is to begin migrating now. HQC is an addition, not a prerequisite.
Is HQC the same family as ML-KEM?
NIST describes ML-KEM as module-lattice based. HQC was a separate fourth round candidate chosen alongside it, which is why it adds a second approach. Read NIST IR 8545 for the technical comparison.
Safeguard's compliance and evidence automation can hold your crypto inventory and migration notes alongside the controls they support, and the free scan at gold.safeguard.sh/scan helps you see your dependency footprint.
Sources
Last reviewed: 19 October 2026.
