I can try this ububtu native toy to study.

Check here to see how to do things https://wiki.ubuntu.com/Testing/Applications/Seahorse

I tested it, and it works fine. But if the key is lost, I will be in big trouble

• here I start

pet@girl:~$ seahorse

• file->new creat a new PGP KEY (used to crypt email and files), I give it a name peter-pgp and apasswd 111111
• then I right click a file peter.txt, right click and choose encryt, then I get a output peter.txt.pgp
• then the encryted file is got, right click if you want to decrypt it.

but I want to know how the reciver can open it, so I

• export peter-pgp as peter-pgp.asc
• right click peter-pgp.asc then gnome showed a message "key imported"
• then I went to seahorse and deleted peter-pgp
• but since peter-pgp.asc was there, so I was confident to open peter.txt.pgp
• but I failed, I hated gui!!

the keys are in ~/.gnupg , it just a front-end of gpg