Information Security Stack Exchange is a question and answer site for information security professionals. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

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?

share|improve this question
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 '14 at 19:07
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 '15 at 19:03
up vote 148 down vote accepted

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.


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 Open WhisperSystems or the rather well known Cryptocat.


  • 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.
share|improve this answer
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 '14 at 16:27
@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. – Terry Chia Apr 5 '14 at 16:39
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 '14 at 14:36
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 '14 at 11:54
Just found out that EFF has given 7/7 of it's secure messaging checklist to Telegram secret chat – Bibhas Mar 13 '15 at 11:34

As of May 2016, this answer is out of date. Whatsapp rolled out E2E encryption.

I will compare Telegram and Whatsapp in 3 aspects: Storage of messages, encryption, and zero-day vurnerabitiles.

In fact I will be comparing 3 technologies: Telegram's regular chats (which I will refer to as "normal chats", or simply "chats"), Telegram's secret chats, and Whatsapp.

0. The fast answer

"end-to-end encrypted, needs more peer review" (Telegram)

Is, in my opinion, better than

"Not end-to-end encrypted, uses closed stuff which cannot be peer reviewed" (Whatsapp)

Opinion aside, here are the facts...

1. Storage

For now, let us assume that both Whatsapp and Telegram completely adhere to their privacy policies.

  • Whatsapp

Whatsapp will not store your chats unless they are not yet delievered to the receipient.

An excerpt from WhatsApp's Legal notes:

The contents of messages that have been delivered by the WhatsApp Service are not copied, kept or archived by WhatsApp in the normal course of business. The WhatsApp Service is meant to be a SMS replacement, using data service through a user’s phone (either via cell network or wifi). Users type their messages, which are sent via data service to our servers, and routed to the intended recipient (who must also be a WhatsApp user), if that recipient is online. If the recipient is not online, the undelivered message is held in WhatsApp’s server until it can be delivered. If the message is undelivered for thirty (30) days, the undelivered message is deleted from our servers.

  • Telegram, regular chats

Telegram stores all your ordinary chats.

An excerpt from Telegram's Privacy Policy:

Ordinary Messages

Telegram is a cloud service. We store messages, photos, videos and documents from your ordinary chats on our servers, so that you can access your data from any of your devices anytime. All data is stored heavily encrypted and the encryption keys in each case are stored in several other DCs in different jurisdictions. This way local engineers or physical intruders cannot get access to user data.

  • Telegram, secret chats

Telegram does not store your secret chats. Even if they did it would probably* be useless because it is end-to-end encrypted.

*See 2. encryption.

Secret Chats

Secret chats use end-to-end encryption. We do not store your secret chats on our servers. We also do not keep any logs for messages in secret chats. What this all means, is that there is no way for us to know who or when you message via secret chats — as soon as the messages are delivered, they're gone. And there is no way for anybody, including us, to learn what was in those messages, photos or videos. For the same reasons secret chats are not available in the cloud — you can only access those messages from the device they were sent to or from

When it comes to storage, Telegram's regular chats are less secure than Whatsapp. However, when it comes to Telegram's secret chats it is superiorly more secure than Whatsapp. Because the data remains encrypted until it reaches the receiving party's phone.

But there is no guarantee that a company obeys its privacy policy. And the NSA revelations have proved so beyond doubt. Assuming that all companies store everything, Telegram secret chats would remain safe thanks to their end-to-end encryption. (Assuming a safe protocol. See next section)

2. Encryption

  • Telegram uses an open non-standard protocol which needs more peer-review.
  • Whatsapp uses an undisclosed protocol. Making peer-review very hard.
  • A Telegram secret chat employs end-to-end encryption using Diffie-Hellman Key exchange. It employs no perfect-forward secrecy.*


As of August 15, 2012, the WhatsApp support staff claim messages are encrypted in the "latest version" of the WhatsApp software for iOS and Android (but not BlackBerry, Windows Phone, and Symbian), without specifying the implemented cryptographic method.

Diffie-Hellman End-to-end encryption is known to be practically unbreakable when used properly even if one does not trust the server passing on the messages.

Therefore, Telegram's secret chats are unbreakable assuming they were used properly and assuming there isn't a serious flaw with the Telegram client software or the crypto. However, as stated earlier, the crypto needs more peer review.

Whatsapp's protocol is undisclosed, we may never know how secure it is.

"Properly" means authentication is achieved. In telegram this should be done by physically meeting with the other party and making sure the barcodes on the two devices are identical. Alternatively, the barcodes can be compared via a channel known to be secure

*Perfect forward secrecy can be emulated by constantly removing chats, re adding them, and re-comparing the keys. But that's hard in practice.

3. Zero-day attacks / Security vulnerabilities

  • Whatsapp is proprietary software.
  • Telegram is open-sourced.

Therefore more eyes are inspecting the code, therefore the likelihood of a vulnerability is far lower. However, Telegram's server-side code is closed-source. But as stated earlier, one needs not to trust the server when one is using secret chats.

Whatsapp has a long history of security vulnerabilities which would have been detected early if it weren't the black box it currently is. (Links soon, you may Google "Whatsapp security" for now)

4. Conclusion

First place: Telegram's secret chats are the king of the ring (When properly used as explained above): Encryption is end-to-end, chats aren't stored, and even if they are being stored: data extraction is probably* impossible thanks to end-to-end DH.

*See 2. encryption.

Second place: If chat storage is of the highest concern for you, Whatsapp comes second. Even though there is no guarantee they obey their privacy policy, there is a 100% guarantee that Telegram stores regular chats, it's part of their policy. If you're really paranoid, second place isn't enough.

If you're worried about the fact that Whatsapp uses some undisclosed black magic which might have hidden vulnerabilities which allow someone to snoop your conversations over the air, and you don't mind companies storing your chats, or believe that companies store your chats anyways, Telegram's regular chats come second. Because needs-more-peer-review is better than uses-unknown-stuff.

Third place: Either Whatsapp or Telegram's regular chats, depending on who you picked second.

Other things to consider

  • Facebook acquired Whatsapp, their policy regarding message storage may change, as Facebook's main revenue relies on data mining. Telegram is a non-profit organization. However, they are backed by, which may have some profit-oriented interest.
  • Telegram's secret chats are great, but comparing barcodes is required for each individual (but NOT for each conversation) you would like to chat with. This might be an inconvenient for some. But this is a general disadvantage of end-to-end cryptography, and is not Telegram-specific. All "Ultimate encryption" protocols need it, a big example is PGP.
  • Telegram is open source and has a completely FOSS version at F-droid which doesn't rely on Google Services or HockeySDK. Generally FOSS is more secure because you know what code you're running and you're assured it contains no evil code.
  • Although the Telegram crypto contest has been criticized, it already yielded some fruit. A weakness in the way secret chat keys are generated has been detected by the community, and the person* who detected it has been awarded $100K. Problems like that would take forever to be detected in a closed protocol like Whatsapp's
  • Following the contest criticism, the Telegram team updated the contest.
  • Telegram's crypto needs more peer review, if it turns out to be vulnerable, the advantage of "secret chats" could fade away. (Opinion: Still better than an undisclosed crypto)
  • Whatsapp recently announced it will end-to-end encrypt all chats by default, However, there is no authentication mechanism yet, this renders it useless. Also, in general closed source software can never be trusted to perform what it claims to perform.

*A rough English translation of the same link.

P.S: I don't have enough reputation to comment on Terry's answer, but I think that referencing the Unhandled Expression blog post is not a good idea because it has many factual errors e.g. Encryption can happen end to end between clients, but there is no authentication. And They will not protect your messages against law enforcement eavesdropping or server compromise. Worse: you cannot detect MITM between you and your peers. The former quote is wrong. The latter quote is true for normal chats, but wrong for Secret Chats. However, this distinction is never made, and throught the post the impression that no authneticated e2e exists is given. In reality you are given the choice between e2e crypto and cloud storage convenience. A valid criticism would be the somewhat buried placement of the barcode button in the UI, which makes some users unaware of its existence.

share|improve this answer
"A non-standard crypto is not necesarilly less secure." Every single respectable cryptographer in the world will disagree with you. – Terry Chia Apr 4 '14 at 12:52
Arguing about that may lead to an extended discussion, so I will avoid it. But please consider editing your answer and not referencing the Unhandled Expression blog post as it is misinformative. I kindly ask that you read it thoroughly, along with the comments. – Hello World Apr 4 '14 at 12:55
As a side note, voting down my answer because of a P.S which I would have posted as a comment if I could is unfair. In case there's an issue with the answer itself, I would love to hear it and possibly correct my mistakes. – Hello World Apr 4 '14 at 13:25
"A non-standard crypto is not necesarilly less secure". Well, many people call "secure" only something that is agreed/proven/widely reputed to be secure, because most protocols are insecure despite the best efforts of many smart people. That definition might be debatable — but if you agree with it, non-standard crypto is certainly less secure because less people have scrutinized it. All that said, Telegram might still be more secure than Whatsapp. – Blaisorblade Jan 5 '15 at 16:28
Hi, I'm the author of the "Unahandlede expression" blog. Since I still get traffic from this page even 2 years after writing that post, I'd like to correct a few things: WhatsApp uses the Axolotl protocol, an improvement on OTR developed by WhisperSystems. They helped Whatsapp in implementing it, so it is closed source, yet reviewed. If you still don't trust closed source, see the open source Python Whatsapp lib, using Axolotl – Géal Dec 12 '15 at 12:00

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:

share|improve this answer
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 at 7:35

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.

share|improve this answer
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 '15 at 20:44
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. – Shiki Jan 14 at 13:51

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

share|improve this answer
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 at 20:00
@John plz see above link that EFF criteria are based on security and privacy and EFF cryptographers compare all messengers in these viewpoints – 0skar Mar 1 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 at 21:46

protected by Community May 8 at 10:16

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.