Social media giant Facebook said on Friday it had started to test end to end encryption on its Messenger application to prevent eavesdropping on digital conversations.
The testing on Messenger, which currently has more than 900 million users, comes just months after the firm rolled out end to end encryption on its WhatsApp app, a messaging app which has 1 billion users, and which Facebook bought out in October 2014.
The move comes amid a far-reaching debate over how far tech firms should go to help law enforcement agencies snoop on our digital communications.
End to end encryption is also provided by Apple’s iMessage service, as well as apps including LINE, Signal, Viber, Telegram and Wickr.
Messenger uses the same encryption as WhatsApp, using a protocol called Signal developed and privately held by Open Whisper Systems.
“It seems well designed”, said Matthew Green, a Johns Hopkins University cryptologist who helped review an early version for Facebook.
WhatsApp messages are encrypted by default, but Facebook Messenger users must enable it to get the added protection, scrambling conversations so they can only be read by devices at either end.
Facebook says it’s requiring users to opt in because encryption is not compatible with some of the most widely used Messenger features.
“Many people want Messenger to work when you switch between devices, such as a tablet, desktop computer or phone”, the company said in an announcement on its website. “Secret conversations can only be read on one device and we recognize that experience may not be right for everyone”.
Facebook says that Messenger users cannot send videos or make payments in encrypted conversations.