GPG Suite, an application that brings encrypted email to Mac OS, is now available in public beta for Sierra.
The software package had been compatible up to El Capitan but wasn't working with Sierra, which was released by Apple in September. The new software can now be downloaded from the GPG Tools website.
It adds support for the OpenPGP encryption standard, which is an open-source version of the PGP encryption package first developed in 1991.
Four software apps are contained in the package:
-- GPG Mail is a plugin for Apple Mail that allows users to encrypt, decrypt, sign, and verify mails sent using OpenPGP.
-- GPG Keychain is a manager for encryption and decryption keys. GPG Services is a plugin that adds GPG encryption to many other applications, and MacGPG is the software that ties it all together.
-- OpenPGP is a public-key encryption system, which requires users to create two keys. A public key which is shared widely and a private key which is kept confidential.
Under the system a user, Alice, encrypts a message to a second user, Bob, using Bob's public key. Once done, it can only be decrypted using Bob's private key.
Macworld published a guide to setting up the software in 2015.
In the last several months, encrypted messaging has gotten a higher profile. WhatsApp began encrypting all messages by default in 2016, and secure SMS app Signal has seen a rise in users in the weeks since Donald Trump was elected president of the U.S.
The encryption used in all the systems means messages are kept secure as they traverse the internet and telecom networks to their recipient.