PGP is one of the best methods to do this. It is more assured that the intended recipient and only the intended recipient can read your file. This will require them to generate a private and public key pair. This is what makes PGP a pretty good privacy measure. They just give you the public key in which you encrypt the file with. Nobody but the owner of the private can decrypt the file.
For scenarios like yours is why PGP was created.
A good implementation of OpenPGP is GNU Privacy Guard (gpg). If you have gpg installed and you really just want basic encryption without worrying about the extra security of public and private key pairs, you could use gpg to just password protect a file:
$ gpg -c myfile
And to decrypt this file:
$ gpg myfile.gpg