For example, you can generate public and private keys from Keybase, a PGP key database. On Keybase, you can also encrypt and decrypt messages and view the public keys of other PGP users.

If you want to see if it’s available for your account, head to your Facebook settings, look for the contact info section and you should see the option to add a PGP public key.

I've been looking around the internet for an example that shows how to encrypt a file with an existing PGP public key that was sent to me. The examples I find generate the key pair on the fly and ...