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There is a new WhatsApp-killer application called Telegram. They said that it's open source and that it has a more secure encryption.

But they store all the messages in their servers and WhatsApp doesn't store any messages in any server, only a local copy in the phones.

Is Telegram more secure than WhatsApp?

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    In short, I'd say nothing is secure that works as easy as Telegram, WhatsApp, Skype, BlackBerry, etc. All of those (except WhatsApp) have promised end to end encryption, and so far only Telegram is not known to hand over their encryption keys to governments, simply because they are not big enough yet. Somehow Microsoft and Blackberry made it possible to break their own security and provide India and the United Arab Emirates with some plaintext. I wouldn't put it past any app to do this. For real security, use trusted tools like PGP/GPG or OTR.
    – Luc
    Apr 5, 2014 at 19:07
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    They did a roll-your-own on their encryption... So, no. Hilarity from the future, enjoy! Said someone who examined it, "The crypto is like being stabbed in the eye with a fork."
    – Fiasco Labs
    Nov 23, 2015 at 19:03
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    Judging from the fact that the Russian gov won the trial related to the encryption and ordered them to subdue their keys, no.
    – Michael Chourdakis
    Mar 20, 2018 at 17:14
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    As mentioned in the edit here all of this thread should be renamed to just apply to the first version of MTProto. After 2017 it ceased to be relevant.
    – mirh
    Jan 11, 2021 at 13:03

6 Answers 6

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TL;DR: No, Telegram is not secure.

I'd like to ignore the comparison to WhatsApp because WhatsApp does not advertise itself as a "secure" messaging option. I'd like to instead focus on whether Telegram is secure.

Telegram's security is built around their home spun MTProto protocol. We all know that the first rule of Cryptography is Don't Roll Your Own Crypto. Especially if you aren't trained cryptographers. Which the Telegram people most certainly aren't.

The team behind Telegram, led by Nikolai Durov, consists of six ACM champions, half of them Ph.Ds in math. It took them about two years to roll out the current version of MTProto. Names and degrees may indeed not mean as much in some fields as they do in others, but this protocol is the result of thougtful and prolonged work of professionals.

Source: https://news.ycombinator.com/item?id=6916860

Math Ph.Ds are not cryptographers. The protocol they invented is flawed. Here is a nice blog post explaining why. In addition to that, Telegram has issued a rather ridiculous challenge offering a reward to anyone who can break the protocol. Except that the terms they set makes even the most ridiculously weak protocol difficult to break. Moxie Marlinspike has a nice blog post explaining why the challenge is ridiculous.

So, no. Telegram is by no means secure. For commonly accepted definitions of secure, not the one Telegram made up.

If you want a real secure means of communication on your phone, look to more reputable projects such as Signal or WhatsApp (which, since this answer was first written, now uses the Signal Protocol for end-to-end message encryption).

UPDATE

  • 09 January 2015: A new 2^64 attack On Telegram has been announced.
  • 12 December 2015: A new paper demonstrating that MTProto is not IND-CCA secure.
  • 22 December 2017: Replaced outdated recommendation for CryptoCat with a more up-to-date recommendation for Signal and WhatsApp.
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    Reiterates lots of the criticism, but so far I have yet to hear a non-theoretical vulnerability. Can anyone read encrypted messages as they go over the wire, change contents without the other party noticing (even if the attacker doesn't know what the decrypted output will be), or spoof the sender? If not, I don't see a problem with this self-designed protocol. All protocols have been designed by one team or another at some point.
    – Luc
    Apr 5, 2014 at 16:27
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    @Luc I really wish I can downvote comments. Really? Non-standard crypto doesn't make you nervous? Do you want to encourage people to use crypto protocols without strong theoretical foundations? What happens when adoption reaches critical mass and a serious vulnerability is found? Yes, protocols need to be designed by people. But the people designing them should be trained cryptographers and the protocol needs to be peer reviewed by other trained cryptographers.
    – user10211
    Apr 5, 2014 at 16:39
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    Using Cryptocat as an security exemplar is actually quite dangerous. It has a very controversial history, and lots of well known security professionals think it's actually dangerous. So, please remove that from your answer. You should also mention that Moxie worked for OpenWhisper. And that OpenWhisper don't have a usable iOS client.
    – anu
    May 21, 2014 at 14:36
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    An update would be nice. Telegram responded to the linked blogs and it looks like a lot of accusations were based on an out-dated documentation or misunderstanding of it. They also adjusted rules for their hacking contest. Therefore this answer seems deprecated to me.
    – Christian Strempfer
    Aug 18, 2014 at 11:54
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    Just found out that EFF has given 7/7 of it's secure messaging checklist to Telegram secret chat eff.org/secure-messaging-scorecard
    – Bibhas
    Mar 13, 2015 at 11:34
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EFF's Secure Messaging Scorecard currently rates "Telegram (secret chats)" with a 100% security rating. However, the software of the servers Telegram uses is not open; cf. the FAQ "Why not open source everything?"

WhatsApp was docked on the "Is the code open to independent review?" metric. Telegram is now completely open; source code here. Being open, you can verify for yourself that there is no back-doors which could possibly be in a closed app. WhatsApp is closed-source now that it's gone proprietary (Facebook bought it).

A good alternative is Tox or Signal, which is open and peer-to-peer / end-to-end encrypted only and received a high EFF rating.

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As the Telegram FAQ mentions, there is a 'secret chat' option that does not store chats on their servers.

As for the underlying question of, "does storing chats lower their security?" then that is something to consider. Chats being stored on the server does mean that copies can be made on the server for decryption later. This increases the exposure of the messages. Encrypting the messages means that there is a high cost to decrypt the messages, but there is still some exposure.

Taking this added exposure into account, the real question becomes (as it always does), "what are you protecting from?" If you are worried about secure communications in transit, then Telegram 'appears' to be more secure. If you're worried about secure communications at rest, then WhatsApp 'appears' to have a better model, except that none of it is encrypted.

The answer, then, is 'it depends on your focus', and encryption is better than non-encryption, and there is the Telegram's 'secure chat' option.

November 2015:

New research shows deep problems with the crypto: https://medium.com/@thegrugq/operational-telegram-cbbaadb9013a#.gb7od1j6i

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    WhatsApp claims to be encrypted end-to-end using axolotl and it has been verified by WhisperSystems. It's closed source, so you have to trust WhatsApp/WhisperSystems.
    – JaviMerino
    Apr 27, 2016 at 7:35
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    Too many people don't know what they are talking about. In the Medium article, it doesn't talk about "deep problems" with crypto. It just embeds a tweet from Matthew Green with a link to the protocol documentation. The rest of the article has nothing to do with crypto. I suggest you remove the link.
    – XP1
    Apr 20, 2018 at 12:54
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    A Medium article should be considered as authoritative as Buzzfeed. Typically, an opinion expressed on Medium.com yields the opposite of correct information. It cannot conclude a security assessment of Telegram. You can see that the very first sentence of that article exudes garbage.
    – groovenectar
    Jun 3, 2019 at 15:34
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EFF compares all messenger apps and publishes the results in Secure Messaging Scorecard link.

note:EFF compares Telegram in secret chats mode with WhatsApp

EFF criteria are:

  1. encrypted messages in transit? both,telegram uses MTProto protocol and Whatsapp uses an undisclosed protocol
  2. encrypted so the provider can't read it?this criterion requires that all user communications are end-to-end encrypted. This means the keys necessary to decrypt messages must be generated and stored at the endpoints (i.e. by users, not by servers) telegram has this criterion but Whatsapp has not it
  3. can you verify contacts' identities? this criterion requires that a built-in method exists for users to verify the identity of correspondents they are speaking with and the integrity of the channel, even if the service provider or other third parties are compromised telegram has this criterion but Whatsapp has not it
  4. are past communications secure if your key are stolen? this criterion requires that the app provide forward secrecy telegram has this criterion but Whatsapp has not it
  5. is the code open to independent review? telegram has this criterion but Whatsapp has not it
  6. is security design properly documented? this criterion requires clear and detailed explanations of the cryptography used by the application telegram has this criterion but Whatsapp has not it
  7. has there been any recent code audit? this criterion requires an independent security review has been performed within the 12 months prior to evaluation both have it

finally,the result is that Telegram is more secure than Whatsapp

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    This does not add any information to the existing answers. And honestly it does not make much sense to compare to WhatsApp because it does not really have a focus on security. Just by comparing you also have not proven or disproven the security of Telegram.
    – John
    Mar 1, 2016 at 20:00
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    @John plz see above link that EFF criteria are based on security and privacy and EFF cryptographers compare all messengers in these viewpoints
    – user93414
    Mar 1, 2016 at 21:31
  • Yes I am aware. This was already posted by Bibhas in a comment Mar 15. See the comments under Terry Chia's answer. The comparison isn't really meaningful.
    – John
    Mar 1, 2016 at 21:46
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Besides the protocol issues, the app itself is not very secure. In February 2015, Zimperium published a detailed analysis of Telegram's local vulnerability, allowing the attacker to get full access to plain text messages.

Basically, even if the protocol was secure, the application itself isn't, becoming the weak link in secure communication.

According to Zimperium, the Telegram team has never responded to their vulnerability notification. It tells me something about their attitude to security in general, and goes in line, for example, with how they implement "secure chats": no desktop support, graphical-only fingerprint of the key, no possibility to simply enter the key.

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    Messages are not encrypted in memory? If you want to display them on the screen you have to decrypt them, thus storing the string as plain text in memory. How does it make Telegram app not secure?
    – Buddy
    Nov 13, 2015 at 20:44
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    Zimperium is a joke. Their "findings" are always useless. They literally do anything to get into the spotlight for a few seconds. Guess who hyped up Stagefright? Who poured so much money into useless vulnerabilities like this one? Yes, Zimperium. Oh and how many people got hacked using Stagefright? Like... 0.0000000...01%? Maybe? Researchers who followed the steps? || I understand, mobiles are their business. But all they do is fearmongering, nothing else.
    – Apache
    Jan 14, 2016 at 13:51
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According to the Jan. 2021 FBI Infographic re Lawful Access to Secure Messaging Apps Data (PDF), Telegram (along with Signal) are the most secure:

Jan. 2021 FBI Infographic re Lawful Access to Secure Messaging Apps Data

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    This is for "legal" access. Nothing is said about illegal access gained by intercepting communications or having access to a rogue server.
    – A. Hersean
    Dec 2, 2021 at 17:23
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    This doesn't appear to answer the question
    – schroeder ♦
    Dec 2, 2021 at 17:26

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