[aprogrammer]

can anyone point me to a function to encode and decode for a string?

[Keith]

http://www.php.net/base64_encode
http://www.php.net/base64_decode

[UnrealEd]

or you could use the mcrypt functions:
http://be.php.net/manual/en/ref.mcrypt.php

Greetz,
UnrealEd

[NeverMind]

indeed, mcrypt functions are much safer since you get to give your own key of encryption.
base64 is good for normal not secret use since it can be simply decoded with base64_decode()