|Type of project||Free and open-source software, Encryption software, Mobile software|
|Location||San Francisco, CA|
|Owner||Supported and owned by community|
Open WhisperSystems is a collaborative open source project, run by a small group of software developers, that entails the development of a suite of mobile applications to help make communication more private and secure.
Security researcher Moxie Marlinspike and roboticist Stuart Anderson co-founded Whisper Systems in 2010. In addition to launching TextSecure in May 2010, Whisper Systems produced RedPhone, an application that provides encrypted voice calls. They also developed a firewall and tools for encrypting other forms of data. RedPhone and TextSecure played a role in protester communications during the Arab Spring uprisings.
On 28 November 2011, Twitter announced that it had acquired Whisper Systems for an undisclosed amount. Shortly after the acquisition, Whisper Systems' RedPhone service was made unavailable, though it was later released as free and open source software in July 2012. Some have criticized this removal, arguing that it was "specifically targeted [to help] people under repressive regimes" and that it left people like the Egyptians in "a dangerous position" during the events of the 2011 Egyptian revolution.
Whisper Systems' TextSecure software was released as free and open source software about a month after the acquisition by Twitter. The software has since been under open development by the community and has seen a number of new releases based on that open development. The project for this continued work was named Open WhisperSystems.
Toward the end of July 2014, Open WhisperSystems announced Flock, a private contact and calendar cloud sync, and plans to unify its RedPhone and TextSecure applications as Signal. These announcements coincided with the initial release of Signal for iOS.
|This section requires expansion. (May 2014)|
Open WhisperSystems is a collective project made up of volunteers and a growing number of contributors, who are sometimes paid by donations and grants. Open WhisperSystems has received financial support from, among others, the Freedom of the Press Foundation.
Open WhisperSystems' server infrastructure is funded through grants and donations they receive. The server-side architecture is federated. This will likely spread the cost over time. The developers of CyanogenMod already host the servers that handle the traffic for their users.
Twitter has never contributed money or resources to Open WhisperSystems, and is not in control of any of the infrastructure.
TextSecure is an open source encrypted messaging application for Android. TextSecure can be used to send and receive text messages, media and other attachments. By default, the application will send all messages intended to other users of the application as instant messages over Wi-Fi, 3G or LTE. TextSecure encrypts both the message database on the user's device and all messages that are sent to other TextSecure users.
The software that handles message routing for the TextSecure data channel is called TextSecure-Server. The complete source code of the TextSecure server is available on GitHub under the AGPLv3 license. This enables interested parties to examine the code and help the developers verify that everything is behaving as expected. It also allows advanced users to compile their own copies of the software and compare them with the software that is used by Open WhisperSystems and others.
Client-server communication is protected by TLS/SSL. Communication is handled by a REST API and push messaging (both Google Cloud Messaging (GCM) and Apple Push Notification Service (APN)). Support for WebSocket has been added.
RedPhone is an application that provides encrypted voice calls for users of the Android operating system and its derivatives. The application enables encrypted voice communication between its users. RedPhone integrates with the system dialer to provide a frictionless call experience, but uses ZRTP to set up an encrypted VoIP channel for the actual call. RedPhone was designed specifically for mobile devices, using audio codecs and buffer algorithms tuned to the characteristics of mobile networks, and uses push notifications to preserve the user's device's battery life while still remaining responsive.
Flock is a secure syncing service for android which securely syncs calendar and contact information on android devices. Users have the ability to host their own server. 
- "Members of Open WhisperSystems on GitHub".
- Garling, Caleb (2011-12-20). "Twitter Open Sources Its Android Moxie | Wired Enterprise". Wired.com. Retrieved 2011-12-21.
- "Company Overview of Whisper Systems Inc.". Bloomberg Businessweek. Retrieved 2014-03-04.
- Andy Greenberg (2010-05-25). "Android App Aims to Allow Wiretap-Proof Cell Phone Calls". Forbes. Retrieved 2014-02-28.
- Robert Lemos (2011-02-15). "An App for Dissidents". MIT Technology Review. Retrieved 2014-03-07.
- Tom Cheredar (November 28, 2011). "Twitter acquires Android security startup Whisper Systems". VentureBeat. Retrieved 2011-12-21.
- Andy Greenberg (2011-11-28). "Twitter Acquires Moxie Marlinspike's Encryption Startup Whisper Systems". Forbes. Retrieved 2011-12-21.
- Garling, Caleb (2011-11-28). "Twitter Buys Some Middle East Moxie | Wired Enterprise". Wired.com. Retrieved 2011-12-21.
- Pete Pachal (2011-12-20). "Twitter Takes TextSecure, Texting App for Dissidents, Open Source". Mashable. Retrieved 2014-03-01.
- "A New Home". Open WhisperSystems. 2013-01-21. Retrieved 2014-03-01.
- Max Eddy (Mar 11, 2014). "Snowden to SXSW: Here's How To Keep The NSA Out Of Your Stuff". PC Magazine: SecurityWatch. Retrieved 2014-03-16.
- Hanno Böck (Mar 11, 2014). "Snowden empfiehlt Textsecure und Redphone" (in German). Golem.de. Retrieved 2014-03-16.
- "Free, Worldwide, Encrypted Phone Calls for iPhone". 29 July 2014.
- "Open WhisperSystems". Freedom of the Press Foundation.
- Moxie Marlinspike (Mar 11, 2014). "How is openwhispersystems paying for the its server costs?". Open WhisperSystems. Retrieved 16 March 2014.
- Moxie Marlinspike (May 5, 2014). "1. What is TextSecure's ...". Retrieved 6 May 2014.
- DJ Pangburn (3 March 2014). "TextSecure Is the Easiest Encryption App To Use (So Far)". Motherboard. Retrieved 14 March 2014.
- Brian Donohue (Feb 24, 2014). "TextSecure Sheds SMS in Latest Version". Threatpost. Retrieved 2014-03-01.
- Christine Corbett (Mar 27, 2013). "Sure!". Open WhisperSystems. Retrieved 2014-03-16.
- "TextSecure on GitHub". Retrieved 26 February 2014.
- Molly Wood (19 February 2014). "Privacy Please: Tools to Shield Your Smartphone". The New York Times. Retrieved 26 February 2014.
- Moxie Marlinspike (24 February 2014). "The New TextSecure: Privacy Beyond SMS". Open WhisperSystems. Retrieved 26 February 2014.
- Martin Brinkmann (24 February 2014). "TextSecure is an open source messaging app with strong security features". Ghacks Technology News. Retrieved 26 February 2014.
- The Guardian Project. "Secure Mobile Apps". GuardianProject.info. Retrieved 26 February 2014.
- "TextSecure-Server on GitHub". Retrieved 2 March 2014.
- Open WhisperSystems. "Why do I need Google Play installed to use TextSecure on Android?". Retrieved 2014-03-13.
- "RedPhone on GitHub". Retrieved 2 March 2014.
- "Flock". Retrieved 31 July 2014.
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