PASETO is a specification for secure, stateless authentication tokens. fpast2l is Go implementation of only the secret/symmetric part of version 2 of the PASETO spec.
There exists at least one implementation: o1egl/paseto, that covers the complete PASETO specification, is probably better written and better documenting. You should be using that instead.
The aim of fpast2l is not to be a complete or compatible implementation of the entire PASETO standard. It is written to meet specific needs and has no ambition for any sort of general use.
The key aim is to implement fast v2.local token generation in pure-Go with
the least amount of garbage possible. It is currently not completely garbage
free, which is what the roadmap will focus on. It is, however, slightly faster
than o1egl's implementation and produces less garbage.