Encrypt This! allows public key like encryption as well as passphrase methods.
Encrypt This! it`s a Text Encryption.
Visit the extension`s homepage to set up public and private keys or just go ahead with a passphrase of your own creation.
Using Encrypt This! you can select text and have it encrypted in one click. This will allow you to send emails more securely by ensuring that nobody other than your intended recipient can read the decrypted text.