Method to parse untrusted footer?

[Imberflur]

Is your feature request related to a problem? Please describe.

The rusty_paseto::core::Footer docs and the PASETO spec note that the footer can be useful for key rotation. This requires reading it before decrypting/verifying the token. However, I can't seem to find any method for parsing out the footer from a token? In fact, AFAICT it seems like the token parser requires the user to know what the footer is if one is present?

Describe the solution you'd like

A new method for parsing an untrusted footer.

Describe alternatives you've considered

• Manually implementing this parsing outside of rusty_paseto.
• Passing information for key rotation separate from the token.