http://bkg5ofjslnbyqvu55sjonpdyp3wmfsgq23u7vpk3wxn7ewgdeocpgwid.onion?page=article&article=Secure+Collaboration%3A+Encrypting+Group+Communication+with+GPG.html
Let’s say you want to share a confidential document or message with a group of colleagues: Alice, Bob, and Charlie. You have their public keys, and you want to make sure that only they can decrypt the message. GPG allows you to encrypt the message for all three recipients in one go.