How to encrypt and sign text or files with GPG Services?

Encrypt files

1. right-click the file or folder you want to encrypt in Finder and select Services > OpenPGP: Encrypt File
   
2. select recipients to encrypt the message with their public keys - if you only want to encrypt for yourself you need to tick the Add to Recipients option in the Your Key: section
   
3. optionally sign the file to ensure it did not get tampered with when decrypting after some time
   
4. click Encrypt
   
5. a new .gpg file will be created next to the original file, if you do not want to keep the unencrypted file make sure to delete it securely

To sign a file select Services > OpenPGP: Sign File.

Encrypt text

1. open TextEdit (do not use Word, Pages or other formatting TextEditors)
   
2. open TextEdit > Preferences and make sure you have selected Plain text as format
   
3. paste or type your message
   
4. press ⌘A to select all text
   
5. right-click and select Services > OpenPGP: Encrypt Selection
   
6. select recipients to encrypt the message with their public keys - if you only want to encrypt for yourself you need to tick the Add to Recipients option in the Your Key: section
   
7. click Encrypt and you will see the encrypted text in TextEdit

To only sign a text message select Services > OpenPGP: Sign Selection.

Note: GPG Services is invoked via right-click. Sadly some programs do not offer a services menu option. Known cases are Firefox and Atom. For Firefox you can invoke GPG Services via menubar > Program name > Services > OpenPGP: …, sadly for Atom no workaround is available. You can ask GitHub to add the functionality in the open issue.