Post-quantum signatures
Signatures are a different migration from key establishment.
What can go wrong
Delaying them because they are not a harvest-now, decrypt-later problem, and then discovering the PKI and the verifiers cannot move in the time you have left.
A stronger practice
NIST IR 8547, October 2026, says signatures are not vulnerable to harvest-now, decrypt-later. It says the transition is still urgent because it takes longer and more parties must coordinate. It says an authentication system remains secure until the algorithm can be broken at the time of authentication, and that supporting a quantum-resistant algorithm means upgrading the systems that perform and accept the authentication, including the PKI.
FIPS 204 specifies ML-DSA and FIPS 205 specifies SLH-DSA. ML-DSA and SLH-DSA are the two NIST signature algorithms. This edition does not link the FIPS and does not reprint their parameters.
If the checker cannot be updated later, go to Long-lived roots.
Secure Boot and signing, keys, and credentials are onward reading. They are not the authority for the post-quantum clock.
What to ask
Who has to change at the same time, and can the checker be updated later?
Evidence
The list of parties and the date they can move.
A weak answer
"Signatures can wait until quantum computers arrive."
A stronger answer
"The document-signing service has a long coordination lead. It is on this year's plan for that reason. The recorded-traffic problem is on the key-establishment page."
Which pass
A long coordination lead can put signatures on the first pass even though they are not a harvest-now, decrypt-later problem. The reason is the time the parties need, which NIST IR 8547 states.
Options
ML-DSA and SLH-DSA are the two NIST signature algorithms named here. The choice between a signature migration and a key-establishment migration is on Priority. A root that cannot update its check later is on Long-lived roots, not a general signature project.
Sources
- NIST IR 8547, Transition to Post-Quantum Cryptography Standards, October 2026. NIST IR 8547