Telegram (software)

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Telegram logo.svg
Telegram Android screenshot.png
Telegram on Android
Developer(s) Telegram Messenger LLP
Initial release August 2013 (2013-08)
Stable release

Android 1.6.1 (July 20, 2014; 31 days ago (2014-07-20)}[1]) [±]
iOS 2.5 (July 23, 2014; 28 days ago (2014-07-23)[2]) [±]
Windows Phone (July 21, 2014; 30 days ago (2014-07-21)[3]) [±]
Web app 0.2.8 (July 31, 2014; 20 days ago (2014-07-31)[4]) [±]
Mac OS X 1.27 (July 16, 2014; 35 days ago (2014-07-16)[5]) [±]

Desktop 0.5.12 (July 30, 2014; 21 days ago (2014-07-30)[6]) [±]
Operating system Google Android, Apple iOS, Windows Phone, MS Windows, Linux, Mac OS X
Available in English, Arabic, Spanish, German, Italian, Dutch, Portuguese (Brazil & Portugal)
Type Instant messaging
License GPL v2 (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 devices without Wi-Fi). 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.[7][8]


Telegram was launched in 2013 by the brothers Nikolai and Pavel Durov, the founders of VK, Russia's largest social network.[9] Telegram Messenger LLP is an independent nonprofit company based in Berlin, which is not connected to VK.[citation needed] Nikolai created the new MTProto protocol that the messenger is based on, while Pavel provided financial support and infrastructure through his Digital Fortress fund.[10]

In October 2013, Telegram had 100,000 daily active users.[9] On 24 March 2014, Telegram announced that it has reached 35 million monthly users and 15 million daily active users.[11]

Cryptanalysis contests[edit]

On December 19, 2013, Telegram backer Pavel Durov announced that he would give $200,000 in bitcoins to anyone able to decipher intercepted Telegram traffic.[12][13]

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.[14]

On March 1, 2014 the first contest ended with no winners and Telegram published the keys necessary to decrypt traffic.[15][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.[15][16]


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.[17] 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.[18]

  • Conversations are encrypted with AES-256 using the MTProto protocol developed by Telegram [9][19][20]
  • 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.[21]
  • Can send voice notes, photos, videos, and files of all types
  • Groups for 200 members.[22]
  • 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)[23]



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.[24]


All official Telegram clients (and some of the unofficial clients) are open source.[25] 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.[26]

Security concerns[edit]

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.[27][28][29][30][31]

See also[edit]


  1. ^ Telegram Messenger LLP (July 20, 2014). "Telegram". Google Play. Google. Retrieved July 20, 2014. 
  2. ^ Telegram Messenger LLP (July 23, 2014). "Telegram HD". App Store. Apple. Retrieved July 23, 2014. 
  3. ^ Telegram Messenger LLP (July 21, 2014). "Telegram Messenger Beta". Windows Phone Marketplace. Microsoft. Retrieved July 21, 2014. 
  4. ^ Igor Zhukov (zhukov) (July 31, 2014). "Webogram". Web application. GitHub. Retrieved July 31, 2014. 
  5. ^ Mikhail Filimonov (July 16, 2014). "Messenger for Telegram". Mac App Store. Apple. Retrieved July 16, 2014. 
  6. ^ telegramdesktop (July 30, 2014). "Telegram Desktop". Web application. Website. Retrieved July 30, 2014. 
  7. ^ "List of Telegram applications". 2014-02-06. 
  8. ^ "Che cosa è Telegram," (in Italian). 
  9. ^ a b c "Meet Telegram, A Secure Messaging App From The Founders Of VK, Russia’s Largest Social Network". TechCrunch. 2013-10-27. 
  10. ^ "Russia’s Zuckerberg launches Telegram, a new instant messenger service". Reuters. 2013-08-30. 
  11. ^ Telegram Hits 35M Monthly Users, 15M Daily With 8B Messages Received Over 30 Days, TechCrunch, 2014-03-24 
  12. ^ "Crypto contest announcement". Telegram. Retrieved 2014-06-02. 
  13. ^ "Telegram offers award to crack encryption". BBC. 2013-12-19. Retrieved 2013-12-30. 
  14. ^ "Crowdsourcing a More Secure Future". Telegram blog. 21 Dec 2013. Retrieved 3 March 2014. 
  15. ^ a b "Winter Contest Ends". Telegram blog. 2 Mar 2014. Retrieved 3 March 2014. 
  16. ^ "Telegram Contest FAQ". Retrieved 3 March 2014. 
  17. ^ New instant messenger Telegram protected even from spy intrusions, VentureBeat, 2013-11-12 
  18. ^ Telegram FAQ, retrieved 10 February 2014 
  19. ^ Telegram F.A.Q.: How secure is Telegram? 
  20. ^ Description of MTProto Mobile Protocol 
  21. ^ List of Telegram applications, retrieved 2014-02-23 
  22. ^ Should WhatsApp be wary of Telegram?, 2014-02-13 
  23. ^ Telegram F.A.Q.: What do the green ticks mean?, 2014-02-23 
  24. ^ Telegram technical FAQ for Advanced users 
  25. ^ Telegram source code links, retrieved 2013-02-12 
  26. ^ "Pavel Durov: "No application is 100% safe"", El Diario Turing, 2014-02-02, retrieved 2014-02-12 
  27. ^ Moxie Marlinspike (19 Dec 2013). "A Crypto Challenge For The Telegram Developers". Retrieved 2 March 2014. 
  28. ^ Taylor Hornby (19 Dec 2013). "Telegram's Cryptanalysis Contest". Crypto Fails. Retrieved 2 Mar 2014. 
  29. ^ Robin Wauters (19 Dec 2013). "Cracking contest: first one who breaks Telegram gets $200,000 in bitcoins (but really, nobody wins)". Retrieved 2 March 2014. 
  30. ^ Geoffroy Couprie (17 December 2013). "Telegram, AKA "Stand back, we have Math PhDs!"". Retrieved 2 April 2014. 
  31. ^ Thijs Alkemade (2 April 2014). "Breaking Half of the Telegram Contest". Retrieved 2 April 2014. 

External links[edit]