|Developer(s)||Telegram Messenger LLP|
|Operating system||Google Android, Apple iOS, Windows Phone, MS Windows, Linux, Mac OS X|
|Available in||English, Arabic, Spanish, German, Italian, Basque|
|License||GNU GPL2 (client), closed source (server)|
Telegram Messenger is a cross-platform messenger whose clients are open source. Telegram users can exchange encrypted and self-destructing messages, photos, videos and documents (all file-types supported). Telegram is officially available for Android and iOS (including tablets and no-wifi devices). Unofficial clients for Windows Phone, as well as a Web version, OS X version, Linux version and a Windows desktop client are available from independent developers using the Telegram API.
Telegram was launched in 2013 by the brothers Nikolai and Pavel Durov, the founders of VK, Russia's largest social network. Telegram Messenger LLP is an independent nonprofit company based in Berlin, which is not connected to VK. Nikolai created the new MTProto protocol that the messenger is based on, while Pavel provided financial support and infrastructure through his Digital Fortress fund.
On December 21, 2013, a Russian IT-community user discovered a security problem in Telegram. The user was rewarded with a $100,000 USD bounty after it was fixed.
On March 1, 2014 the first contest ended with no winners and Telegram published the keys necessary to decrypt traffic.[clarification needed] Telegram claims that challenges to break their crypto are a permanent feature of the project and announced that they are working on a new contest that would allow more active attacks.
Telegram claims it is more secure than mass market messengers like WhatsApp and LINE. The application features two types of chats. Ordinary chats use client-server encryption and can be accessed from multiple devices. Secret Chats use end-to-end encryption and can only be accessed from the two participating devices. Telegram claims that third parties, including the Telegram administrators, cannot get access. Messages and media in Secret Chats can also be set to self-destruct in a set period of time after being read. Once the time runs out, the messages disappear from both devices.
||This section is in a list format that may be better presented using prose. (March 2014)|
- Conversations are encrypted with AES-256 using the MTProto protocol developed by Telegram 
- Chat history is stored on Telegram cloud servers and can be accessed from any number of devices
- Has mobile versions, desktop versions and browser extensions.
- Can send voice notes, photos, videos, and files of all types
- Groups for 200 members.
- Secret chats with end-to-end encryption that are not stored on the servers
- Auto-destructing messages in secret chats (like Snapchat)
- Message read status: 1 check = sent, 2 checks = read (opened)
|This section requires expansion. (March 2014)|
All chats are encrypted with the new MTProto protocol created by Nicolai Durov, regardless of type. This is based on 256-bit symmetric AES encryption, RSA 2048 encryption and Diffie–Hellman secure key exchange.
All official Telegram clients (and some of the unofficial clients) are open source. Telegram's server-side software, however, is closed source proprietary software. Pavel Durov mentioned that the server code is not free software, because Telegram requires a major redesign of architecture in order to allow independent servers to exchange data and act as a part of the unified Telegram cloud.
Several members of the cryptographic community, including security researchers Moxie Marlinspike and Taylor Hornby, have criticized Telegram's cryptanalysis contests and the MTProto protocol developed by Telegram.
Telegram clients are open source, so it is possible to verify that the end-to-end encryption mechanism is in use.[clarification needed] Telegram's server-side software, however, is closed source proprietary software. It is not possible to verify whether the claimed encryption standards are properly used and well implemented when it comes to ordinary messages. Furthermore, it can not be verified if the servers are free of intentional or accidental security flaws. Attempting to reverse engineer the software is illegal in the EU. In the US the "fair use" doctrine may be applicable.
- "List of Telegram applications". 2014-02-06.
- "Che cosa è Telegram, Squer.it" (in Italian).
- "Meet Telegram, A Secure Messaging App From The Founders Of VK, Russia’s Largest Social Network". TechCrunch. 2013-10-27.
- "Russia’s Zuckerberg launches Telegram, a new instant messenger service". Reuters. 2013-08-30.
- Telegram Hits 35M Monthly Users, 15M Daily With 8B Messages Received Over 30 Days, TechCrunch, 2014-03-24
- "Crypto contest announcement". Telegram. Retrieved 2014-06-02.
- "Telegram offers award to crack encryption". BBC. 2013-12-19. Retrieved 2013-12-30.
- "Crowdsourcing a More Secure Future". Telegram blog. 21 Dec 2013. Retrieved 3 March 2014.
- "Winter Contest Ends". Telegram blog. 2 Mar 2014. Retrieved 3 March 2014.
- "Telegram Contest FAQ". Retrieved 3 March 2014.
- New instant messenger Telegram protected even from spy intrusions, VentureBeat, 2013-11-12
- Telegram FAQ, retrieved 10 February 2014
- Telegram F.A.Q.: How secure is Telegram?
- Description of MTProto Mobile Protocol
- List of Telegram applications, retrieved 2014-02-23
- Should WhatsApp be wary of Telegram?, 2014-02-13
- Telegram F.A.Q.: What do the green ticks mean?, 2014-02-23
- Telegram technical FAQ for Advanced users
- Telegram source code links, retrieved 2013-02-12
- "Pavel Durov: "No application is 100% safe"", El Diario Turing, 2014-02-02, retrieved 2014-02-12
- Moxie Marlinspike (19 Dec 2013). "A Crypto Challenge For The Telegram Developers". Retrieved 2 March 2014.
- Taylor Hornby (19 Dec 2013). "Telegram's Cryptanalysis Contest". Crypto Fails. Retrieved 2 Mar 2014.
- Robin Wauters (19 Dec 2013). "Cracking contest: first one who breaks Telegram gets $200,000 in bitcoins (but really, nobody wins)". Tech.eu. Retrieved 2 March 2014.
- Geoffroy Couprie (17 December 2013). "Telegram, AKA "Stand back, we have Math PhDs!"". Retrieved 2 April 2014.
- Thijs Alkemade (2 April 2014). "Breaking Half of the Telegram Contest". Retrieved 2 April 2014.
- Due to possible copyright violations. For the (strict) software copyright within the territory of the EU read Hoehne, IT in general aviation: Pen and Paper vs. Bits and Bytes, pp. 26-27. In the US the "fair use" doctrine may be applicable.