telegram-mt-old

Disclaimer: I am not a cryptographer, and have only gotten to #40 in Matasano's challenges. They appear to be trying to use encrypt and mac, and not as far as I can tell relying on IGE mode to provide authentication. See the "Message Key" and "Important Tests" sections here: https://core.telegram.org/mtproto/description There is also not, as far as I can tell from reading the protocol description above and the source code here: https://github.com/ex3ndr/telegram-mt/blob/master/src/main/j... (in particular the EncryptedMessage method, lines 447 to 460) any sort of key in the MAC, it's just SHA-1 of the plaintext. It's also not encrypted as far as I can tell, it's listed in the unencrypted "external header" in the protocol description. I can't think of an attack from this, but the fact that an adversary can generate a valid MAC for _any

Great, let's take a quick look. TcpContext.java[1] says: MAX_PACKED_SIZE = 1024 * 1024 * 1024;//1 MB READ_DIE_TIMEOUT = 5 * 1000; // 15 sec So those are bugs, though I'm not sure if documentation or code. Most importantly to me, there are very few comments in the code, and the few there are are incorrect. One might infer that this code has been written either in haste, or by someone who believes that comments are not needed in this sort of systems code. There are also writeInt() and readInt() method which seems to be little-endian, which seems odd for a network program. No comments near them. Finally, there's a "Package" class which is just a byte array and a flag. And there's a method which writes it after a cute encoding for the length divided by 4. But there is no code which checks that the length is evenly divisible by 4

Interesting. Some observations: TextSecure has been a work in progress for two years: https://github.com/WhisperSystems/TextSecure/commits/master?... Telegram seems to have been in progress for two months: https://github.com/ex3ndr/telegram-mt/commits/master?page=2 Telegram also seems to be the work of a single author. While TextSecure was written mostly by Moxie, there were several other contributing members.

You are correct to be wary. However, the MTProto java impl is here: https://github.com/ex3ndr/telegram-mt