It works on scalar data; the data doesn't have to be in files. Look at the 'Data' parameter to encrypt and sign, in particular; that lets you specify the data to be encrypted/signed as a scalar string, rather than as a filename.

And all of the methods return data as a scalar; they don't write data to a file.

Furthermore, you can always go under the hood and use the lower-level interface in the other modules if you wish. I will add some "SEE ALSO" sections to the main Crypt::OpenPGP docs, but the other classes are all documented (basically :), so they should be useable on their own.

BTW: As for tutorial and examples: at the moment the best I can offer for examples is the test suite and the SYNOPSIS. Examples will come in the future.