Researched
End-to-End Encrypted Messaging
The Signal Protocol (2013-14) lets only sender and recipient read a message; WhatsApp switched it on for all its users on 5 April 2016, when it had over one billion.
Open in the interactive tree →Phil Zimmermann's PGP (1991) had brought end-to-end encryption to e-mail, but it stayed hard to use. Moxie Marlinspike and Trevor Perrin built TextSecure on Off-the-Record messaging in 2013 and added the Double Ratchet, which changes keys with every message so that one stolen key exposes little. WhatsApp announced the partnership in November 2014 and completed encryption of every message, call and group chat on 5 April 2016. Governments have since pressed for access to such messages, for example in the UK's Online Safety Act (2023).
Prerequisites
- Public-Key Cryptography1976Keys are exchanged and signed with public-key methods.
- Smartphone2007Phones are where billions of people send messages.