Key establishment and digital signatures are different migration problems

Post-quantum terminology becomes less confusing when the cryptographic job is explicit. A key-establishment mechanism helps communicating parties establish a shared secret. A digital signature helps verify origin and detect unauthorized modification. They are not interchangeable substitutes. NIST describes FIPS 203 as a key-encapsulation mechanism standard and FIPS 204 and 205 as digital signature standards. That separation should appear in a migration plan, a vendor questionnaire, and any public explanation.

Ask the role first

Before choosing an algorithm or library option, identify whether the system needs key establishment, encryption using an established key, signing, verification, certificates, or several of these together. Record the protocol version and peer compatibility requirements.

Test the whole path

A library can support an algorithm while an application, intermediary, certificate workflow, or hardware module does not. Test the actual endpoints, messages, error handling, monitoring, and fallback behavior. Do not call a product quantum-safe without defining the path and threat model. A precise role label improves both technical accuracy and planning. It tells readers which evidence they should request next.