Signal Adds Expiring Messages to Encrypted Chats

The steady march toward greater use of encryption and increased privacy in mobile communications has taken another step forward with Signal, the encrypted messaging app, introducing disappearing messages.
The newest version of Signal for both iOS and Android, as well as the desktop app, include the feature, which enables users to set timers for when their private messages will expire. Users can set the expiration time from a few seconds to as long as a week. The feature is intended to give users another line of defense against their private messages being read by a third party.
“With this update, any conversation can be configured to delete sent and received messages after a specified interval. The configuration applies to all parties of a conversation, and the clock starts ticking for each recipient once they’ve read their copy of the message,” Moxie Marlinspike, founder of Open Whisper Systems, Signal’s developer, said in a post introducing the new feature.
“Disappearing messages are a way for you and your friends to keep your message history tidy. They are a collaborative feature for conversations where all participants want to automate minimalist data hygiene, not for situations where your contact is your adversary — after all, if someone who receives a disappearing message really wants a record of it, they can always use another camera to take a photo of the screen before the message disappears.”
The Signal protocol is the underlying foundation of several other encrypted messaging systems, including Facebook’s Secret Conversations and Google Allo. It’s designed to encrypt communications from end to end and prevent any adversary along the way from being able to read those messages. The Signal app implements the protocol differently than either Facebook or Google, encrypting all conversations by default and storing nothing on the company’s servers.
Image from Flickr stream of Nicolas Will.