Security Analysis Of The Telegram IM presented at deepsec 2017

by Josef KokeŇ°, Tomas Susanka,

Summary : Telegram is a popular instant messaging service, a self-described fast and secure solution. It introduces its own home-made cryptographic protocol MTProto instead of using already known solutions, which was criticised by a significant part of the cryptographic community. In this talk, we will briefly introduce the protocol and then present two major findings we discovered as part of our security analysis performed in late 2016. First, the undocumented obfuscation method Telegram uses, and second, a replay attack vulnerability we discovered. The analysis was mainly focused on the MTProto protocol and the Telegram's official client for Android.