2013–2018: Open Whisper Systems
Marlinspike launched Open Whisper Systems' website in January 2013.
In February 2014, Open Whisper Systems introduced the second version of their TextSecure Protocol (now Signal Protocol), which added end-to-end encrypted group chat and instant messaging capabilities to TextSecure.[7] Toward the end of July 2014, Open Whisper Systems announced plans to unify its RedPhone and TextSecure applications as Signal. These announcements coincided with the initial release of Signal as a RedPhone counterpart for iOS. The developers said that their next steps would be to provide TextSecure instant messaging capabilities for iOS, unify the RedPhone and TextSecure applications on Android, and launch a web client. Signal was the first iOS app to enable easy, strongly encrypted voice calls for free. TextSecure compatibility was added to the iOS application in March 2015.
On 18 November 2014, Open Whisper Systems announced a partnership with WhatsApp to provide end-to-end encryption by incorporating the Signal Protocol into each WhatsApp client platform. Open Whisper Systems said that they had already incorporated the protocol into the latest WhatsApp client for Android and that support for other clients, group/media messages, and key verification would be coming soon after. WhatsApp confirmed the partnership to reporters, but there was no announcement or documentation about the encryption feature on the official website, and further requests for comment were declined. On 5 April 2016, WhatsApp and Open Whisper Systems announced that they had finished adding end-to-end encryption to "every form of communication" on WhatsApp, and that users could now verify each other's keys.[8][9] In September 2016, Google launched a new messaging app called Allo, which features an optional "incognito mode" that uses the Signal Protocol for end-to-end encryption.[10][11] In October 2016, Facebook deployed an optional mode called "secret conversations" in Facebook Messenger mobile apps which provides end-to-end encryption using an implementation of the Signal Protocol.[12][13][14]
In November 2015, the TextSecure and RedPhone applications on Android were merged to become Signal for Android.[15] A month later, Open Whisper Systems announced Signal Desktop, a Chrome app that could link with a Signal client.[16] At launch, the app could only be linked with the Android version of Signal.[16] On 26 September 2016, Open Whisper Systems announced that Signal Desktop could now be linked with the iOS version of Signal as well.[17] On 31 October 2017, Open Whisper Systems announced that the Chrome app was deprecated. At the same time, they announced the release of a standalone desktop client for certain Windows, MacOS and Linux distributions.[18]
On 4 October 2016, the American Civil Liberties Union (ACLU) and Open Whisper Systems published a series of documents revealing that OWS had received a subpoena requiring them to provide information associated with two phone numbers for a federal grand jury investigation in the first half of 2016.[19][20][21] Only one of the two phone numbers was registered on Signal, and because of how the service is designed, OWS was only able to provide "the time the user’s account had been created and the last time it had connected to the service".[20][19] Along with the subpoena, OWS received a gag order requiring OWS not to tell anyone about the subpoena for one year.[19] OWS approached the ACLU, and they were able to lift part of the gag order after challenging it in court.[19]
