hmac module and key format

[Stuart Longland]

Hi,

Maybe I'm completely dense with regards to the hmac module and HMAC in
general, but I've searched and cannot find for the life of me the
answer to this very basic question.

What format does hmac require the key to be in?

I have a key in hexadecimal, do I give it the hex?  Do I decode that
to binary and give it that?  Do I try to figure out what passphrase
generated the hex and give it that instead?  Nowhere in the
documentation does it appear to mention what form the key must take,
or how you tell it what form it's in for it to "figure it out".  If
someone could enlighten me, I'd be most grateful.

Regards,
Stuart Longland