Encrypting for Recipient
    gpg --search-keys 'myfriend@his.isp.com' --keyserver hkp://subkeys.pgp.net
    gpg --import key.asc
    gpg --list-keys
    gpg --encrypt --sign --recipient 'myfriend@his.isp.net' foo.txt

Decrypting
    gpg --output decrypted.txt --decrypt encrypted.txt.gpg

Sitnagures
    gpg --verify crucial.tar.gz.asc crucial.tar.gz
    gpg --armor --detach-sign your-file.zip