Telegram (software)

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

Android 2.7.0 (April 8, 2015; 18 days ago (2015-04-08)[1]) [±]
iOS 2.12 (April 8, 2015; 18 days ago (2015-04-08)[2]) [±]
Windows Phone (April 9, 2015; 17 days ago (2015-04-09)[3]) [±]
Web application 0.4.0 (February 16, 2015; 2 months ago (2015-02-16)[4]) [±]
OS X 1.50 (April 10, 2015; 16 days ago (2015-04-10)[5]) [±]

Desktop 0.8.3 (April 8, 2015; 18 days ago (2015-04-08)[6]) [±]
Development status Active
Operating system Android, Apple iOS, Windows Phone, MS Windows, Linux, OS X
Size 9.6 MB (Android), 17 MB (Windowsphone)
Available in English, Arabic, Spanish, German, Italian, Korean, Dutch, Portuguese (Brazil & Portugal)
Type Instant messaging
License GPL v2 (client), closed source (server)
Alexa rank Increase 5,885[7]

Telegram is an instant messaging system focusing on privacy and multi-platform availability. Telegram clients exist for both mobile (Android, iOS, Windows Phone) and desktop systems (Windows, OS X, Linux).[8][9] Telegram users can exchange messages encrypted end-to-end, self-destructing messages, along with photos, videos and files of any type up to 1.5GB in size.

Telegram is run by a German nonprofit organization backed by entrepreneur and philanthropist Pavel Durov. It open-sourced its client code, while server-side code is currently proprietary. Software is also available from independent developers who make use of the Telegram API.


Telegram was launched in 2013 by brothers Nikolai and Pavel Durov, the founders of Russian VK, Russia's largest social network.[10] Telegram Messenger LLP is an independent nonprofit company based in Berlin, Germany,[11] which is not connected to VK.[12] Nikolai created the new MTProto protocol that the messenger is based on, while Pavel provided financial support and infrastructure through his Digital Fortress fund.[13]

In October 2013, Telegram had 100,000 daily active users.[10] On 24 March 2014, Telegram announced that it has reached 35 million monthly users and 15 million daily active users.[14] In December 2014, Telegram announced they had 50 million active users, generating 1 billion daily messages and that they had 1 million new users signing up on their service every week.[15]

Telegram runs contests challenging people to break their cryptography and disclose confidential information within a chat between two fake users. They claim that such challenges will be a permanent feature of their project. On December 21, 2013, a Russian IT-community user discovered a potential vulnerability in Telegram. They rewarded a $100,000 USD bounty after the problem was fixed.[16] On March 1, 2014 their first cryptography contest ended with no winners and they published the keys necessary to decrypt traffic.[17][18] Security researchers Moxie Marlinspike, the founder of Open Whisper Systems, and Taylor Hornby[self-published source] criticized Telegram's first cryptanalysis contest for being no proof of security and misleading the public.[19][20][21][22] Subsequently a new contest which allowed a Man-in-the-middle attack was started.[23]

As of February 17, 2015, Telegram's standard messages score 4 out of 7 points on the Electronic Frontier Foundation's secure messaging scorecard. It receives points for encryption during transit, having the code open to independent review, proper documentation of the security design, and for having had a recent code audit. It misses points because communications are not encrypted with a key the provider does not have access to, users can't verify contacts' identities, and because past messages are not secure if the encryption keys are stolen. In the same evaluation, Telegram's secret chat mode scored 7 out of 7 points.[24]


Telegram accounts are tied to the phone number of the user, with possession of the phone with that number verified with a code sent by SMS or phone call to that phone. Subsequent logins are notified to the initial device with the IP address and time of login.[25] The phone number associated with an account can be changed without losing messages. While availing this migration, contacts of a user who have the previous phone number of the user, and are not blocked by the user, will receive the user's new number automatically.[25][26][27] Users can set up an alias or username which can be used by any other user to contact them, without having to add them to their contacts.[28] is a webservice provided by Telegram which allows directly opening a chat with a user by following a hyperlink (like on supported devices.[26][27]

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.

User accounts are deleted automatically after 6 months of inactivity, and this can be changed to between 1 month and 1 year.

Users can control the 'last seen' timestamps, replacing them with fudged messages like "last seen within a week". They can block other users and silence chats.[29]

One or two checkmarks are displayed to indicate that the message is sent to the cloud or read by the recipient, respectively.[30] It is also possible to see the status of the recipient when responding to a message.[10]

Their latest release saw the introduction of new features such as replies, mentions, link previews and session management.

Standard messages[edit]

With standard messages Telegram supports cloud messaging and file sharing (with multimedia and documents up to 1.5 gigabyte in size) with synchronization across devices.[8][31] The message history can be searched without opening or downloading the conversations.[32] Sharing audio notes, geo-zones, GIFs or animated memes via Giphy[32] are also supported.

Private lists can be made for broadcasting the same message to multiple contacts.[31] Group messaging is possible with up to 200 members in a group, and an unlimited number of groups.[33]

Secret chats[edit]

A "secret chat" confirmation notice. Screenshot in Spanish from Apple iOS 8.

Telegram claims it is more secure than some other messengers such as WhatsApp and LINE. Conversations are encrypted with AES-256 using the MTProto protocol developed by Telegram.[10][34][35] Only two devices may use the secret chat simultaneously.[28]

While using secret chats in official clients, messages deleted on one device are deleted on the other device too, a special message is displayed when a screenshot is taken, and messages can be set to be deleted automatically (self-destruct) at pre-set time intervals.[36]

On December 1, 2014, Telegram implemented Perfect Forward Secrecy in Secret Chats. This enables periodically changing the encryption keys utilized, keeping past communications safe. Official Telegram clients initiate re-keying once a key has been used to decrypt and encrypt more than 100 messages, or has been in use for more than one week, provided the key has been used to encrypt at least one message. Old keys are then discarded and cannot be reconstructed, even with access to the new keys currently in use.[26][27][37]



Explanation of secret chats, included in Telegram, using the keys of the devices, then share the code modified for use as single key encryption and locally synchronized.

The new MTProto protocol created by Nikolai Durov is based on 256-bit symmetric AES encryption, RSA 2048 encryption and Diffie–Hellman key exchange.[38]


All official Telegram clients (and some of the unofficial clients) are open source.[39] Telegram's server-side software, however, is proprietary. Pavel Durov said the server code is not free software because Telegram requires a major architecture redesign to allow independent servers to act as an unified Telegram cloud.[40]

List of applications[edit]

Telegram Web, aka Webogram.

Telegram has various clients with support for more platforms expected in the future. Its server system is decentralized and distributed around the world to improve response times by geographical position.[41] This list includes versions developed on official platforms backed by the development team, or supported by the community to be integrated in the future.


Telegram Desktop running on Arch Linux.



See also[edit]


  1. ^ Telegram Messenger LLP (2 January 2015). "Telegram". Google Play. Google. Retrieved 3 January 2015. 
  2. ^ Telegram Messenger LLP (1 December 2014). "Telegram". App Store. Apple. Retrieved 3 December 2014. 
  3. ^ Telegram Messenger LLP (5 January 2015). "Telegram Messenger Beta". Windows Phone Marketplace. Microsoft. Retrieved 5 January 2015. 
  4. ^ Igor Zhukov (zhukov) (December 16, 2014). "Webogram". Web application. GitHub. Retrieved December 16, 2014. 
  5. ^ Mikhail Filimonov (December 17, 2014). "Messenger for Telegram". Mac App Store. Apple. Retrieved December 17, 2014. 
  6. ^ telegramdesktop (December 27, 2014). "Telegram Desktop". telegramdesktop. Retrieved December 27, 2014. 
  7. ^ " Site Info". Alexa, Inc. Retrieved March 1, 2015. 
  8. ^ a b "List of Telegram applications". 6 February 2014. 
  9. ^ "Che cosa è Telegram," (in Italian). 
  10. ^ a b c d "Meet Telegram, A Secure Messaging App From The Founders Of VK, Russia’s Largest Social Network". TechCrunch. 27 October 2013. 
  11. ^ "Surveillance drives South Koreans to encrypted messaging apps". The Verge. 7 October 2014. 
  12. ^
  13. ^ "Russia’s Zuckerberg launches Telegram, a new instant messenger service". Reuters. 2013-08-30. 
  14. ^ Telegram Hits 35M Monthly Users, 15M Daily With 8B Messages Received Over 30 Days, TechCrunch, 24 March 2014 
  15. ^ Telegram Reaches 1 Billion Daily Messages, Telegram, 8 December 2014 
  16. ^ "Crowdsourcing a More Secure Future". Telegram blog. 21 Dec 2013. Retrieved 3 March 2014. 
  17. ^ "Winter Contest Ends". Telegram blog. 2 Mar 2014. Retrieved 3 March 2014. 
  18. ^ Robin Wauters (19 December 2013). "Cracking contest: first one who breaks Telegram gets $200,000 in bitcoins (but really, nobody wins)". Retrieved 4 December 2014. 
  19. ^ Marlinspike, Moxie (19 Dec 2013). "A Crypto Challenge For The Telegram Developers". Thought crime. Retrieved 2 March 2014. 
  20. ^ Hornby, Taylor (19 Dec 2013). "Telegram's Cryptanalysis Contest". Crypto Fails. Retrieved 2 March 2014. [self-published source]
  21. ^ Wauters, Robin (19 Dec 2013). "Cracking contest: first one who breaks Telegram gets $200,000 in bitcoins (but really, nobody wins)". EU: Tech. Retrieved 2 March 2014. 
  22. ^ Alkemade, Thijs (2 April 2014). "Breaking Half of the Telegram Contest" (World wide Web log). DE. Retrieved 2 April 2014. [self-published source]
  23. ^ "$300,000 for Cracking Telegram Encryption". 
  24. ^ "Secure Messaging Scorecard. Which apps and tools actually keep your messages safe?". Electronic Frontier Foundation. 2015-02-27. 
  25. ^ a b Lopez, Miguel, Configurando Telegram en el iPhone, en la web y en el Mac [Configuring Telegram in the Apple iPhone, the Web and the Mac] (in Spanish), Applesfera, retrieved 4 December 2014 
  26. ^ a b c Munizaga, Jonathan (1 December 2014). "Telegram ya permite migrar conversaciones y contactos a una línea nueva" [Telegram already allows migrating conversations and contacts to a new line] (in Spanish). Wayerless. Retrieved 2 December 2014. 
  27. ^ a b c Mateo, David G (1 December 2014). "Telegram ahora permite traspasar mensajes al cambiar de número" (in Spanish). TuExperto. Retrieved 2 December 2014. 
  28. ^ a b "Secure Messaging App Telegram Adds Usernames And Snapchat-Like Hold-To-View For Media". Techcrunch. Oct 23, 2014. Retrieved 23 October 2014. 
  29. ^ "Basics". FAQ. Telegram. Retrieved 13 February 2014. 
  30. ^ "What do the green ticks mean?", FAQ (Telegram), 23 February 2014 
  31. ^ a b "Telegram: una alternativa gratuita a WhatsApp con ventajas y algún punto oscuro" [Telegram: a free Whatsapp alternative with advantages and some obscure points] (in Spanish). 1 March 2014. Retrieved 4 December 2014. 
  32. ^ a b "Telegram para iOS, Android se actualiza con soporte de GIFs" [Telegram for Apple iOS, Google Android updated with GIF support] (in Spanish). Cnet. Retrieved 12 December 2014. 
  33. ^ "Should WhatsApp be wary of Telegram?". 13 February 2014. 
  34. ^ "How secure is Telegram?", FAQ (Telegram) 
  35. ^ Description of MTProto Mobile Protocol, Telegram 
  36. ^ "Telegram FAQ". n.d. Retrieved 10 February 2014. 
  37. ^ Perfect Forward Secrecy, Telegram, 14 December 2014 
  38. ^ "Telegram technical FAQ for Advanced users". 
  39. ^ "Source code", Telegram (links), retrieved 2013-02-12 
  40. ^ "Pavel Durov: "No application is 100% safe"". Turing. ES: El Diario. 2014-02-02. Retrieved 2014-02-12. 
  41. ^ "Telegram, el chat que compite con Whatsapp" [Telegram, the chat that competes with WhatsApp]. El País (in Spanish). UY. Retrieved 13 February 2014. 
  42. ^ "Telegram se actualiza para la pantalla del iPad" [Telegram updated for the iPad screen] (in Spanish). Cnet. 
  43. ^ "Telegram-Anleitung: So benutzt man den Messenger" (in German). Newsslash. 
  44. ^ "Telegram se actualiza con compatibilidad para Android Wear" [Telegram updated with Android Wear compatibility] (in Spanish). Sevilla: ABC. Retrieved 7 December 2014. 
  45. ^ "Telegram Beta disponible para Windows Phone" [Telegram Beta available for MS Windows Phone] (in Spanish). Wayerless. May 2014. 
  46. ^ a b "Apps". Telegram (in Spanish). Retrieved 21 February 2014. 
  47. ^ "Ngram se convierte en el cliente oficial de Telegram para Windows Phone" [Ngram becomes the official Telegram client for MS Windows Phone] (in Spanish). Retrieved 23 May 2014. 

External links[edit]