Telegram is back in the headlines due to the Russian origins of its creator, Pavel Durov, and also because it is one of the most used applications by the Ukrainian people during the days of the conflict. However, there is a misperception regarding the security of Telegram, which relies on encryption to the proprietary protocol MTProto 2.0, an alternative to Signal Encryption Protocol, developed by Signal and also adopted by WhatsApp. It becomes useful to understand how secure MTProto 2.0 is, contextualizing it to the path and storage of the data that users exchange.
Telegram’s only end-to-end encrypted conversations are the Secret Chats: traditional ones and groups are not. This is information that can escape most people and that has an importance in terms of privacy and dissemination: according to Durov himself, the app has exceeded 500 million active users in January 2021, a quarter compared to the approximately 2 billion users of WhatsApp, but 10 times more than Signal. In other words, Telegram, which remains among the most used messaging applications in the West, has gaps. To better understand the issue, we used the opinion of Danilo Bruschi, full professor of Computer Science at the University of Milan.
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Telegram security
Telegram encryption poses a difficulty of interpretation. In July 2021, a group of specialists highlighted some shortcomings, including the possibility of extrapolating perfectly readable portions of text from encrypted messages. This is a minimal risk, because succeeding in this enterprise is not something for everyone: highly specialized people and technologies are needed. Other researches, one of which carried out by the University of Udine, on the other hand, they claim not to have found any particular weaknesses in MTProto 2.0. It is necessary to understand why, if only from an engineering point of view, Telegram felt the need to create a protocol that adds nothing to the existing ones: “We must clarify – Professor Bruschi explained – that there are essentially 3 actors main in the world of messaging worldwide and are Telegram, WhatsApp and Signal. Telegram uses one encryption standard, while the other two use another and this means that there is no standard in the strict sense of the word. The standards are certified by international bodies and there are de-facto standards that the Net imposes“. That said, “usually something new is created when what is there no longer works or needs improvement. Or you have great firepower and want to impose a new modus operandi on the Net: it happens when a very strong brand arrives that wants to impose its vision of things. Usually it is the Network that then accepts or expels a product ”.
A firepower, that is a significant operational capability that Telegram does not have, especially when compared to that of WhatsApp, which can count on a superior workforce and know-how. However, added Bruschi, “a new protocol is not a bad thing about him: if there were none there would be no innovation”.
The same intervened to complicate the correct interpretation of the security aspects of Telegram Durov, who admitted there are safer competing apps however niche and also added that others do not make encrypted backups. A claim that the creator of Telegram made in 2017: WhatsApp filled some of the gaps in 2016also I know still perfectiblebecause the Meta app requires that the encrypted backup option be activated by the user.
More generally, the IT security of a system is certified by stressing it until its flaws are identified. We can start from the paradox that an older system, and therefore sifted through by security experts for longer, offers more guarantees than a newer one? “It’s not a foregone question. The newer product takes advantage of the most modern research findings, which may not have been there when the older product was made. It is true that the older product should contain fewer flaws, but it is also true that the new product should have absorbed new techniques. So it’s actually quite difficult to be able to make a claim about the safety in this context ”, Bruschi replied.
In establishing how safe Telegram is compared to its direct competitors, we are still at the impasse: “We are in a so-called religious context, there are Telegram’s security advocates over competing apps and supporters of the opposite. Comparing the different apps, there is no clear data that makes one prevail over the other. It is about personal perceptions ”.
Perceptions that have real effects, such as success early 2021, when WhatsApp updated its privacy policies creating the general stampede effect, causing the Telegram app to be downloaded 25 million times within 3 days.
Even earlier, in 2014, WhatsApp has been having trouble functioning for about 3 hourslong enough to push people towards other solutions, and to benefit from it was also Telegram, whose download services have wobbled.
According to Bruschi, “the substantial problem facing users is related to the fact that Telegram is a cloud-based service, centralizes the management of messages and, on the other hand, end-to-end message encryption is not a default, so whoever governs the servers can read the messages. It’s like getting into a car and each time having to activate the airbag protection by entering a code by hand ”.
The perfectible perception of security that users have of Telegram stems from its diffusion. When a competing app has a problem, Telegram, chosen as a migratory stop, enjoys it. The motto is “if it is used a lot, then it is safe”, but safety itself is not a clear topic for everyone: “A normal user is not a safety expert, word of mouth somehow generates a halo around the products. Users cannot do without them, they need to use them for their own sociability ”, is the conclusion of Professor Bruschi. Security is not, at least in principle, the issue that is most at heart to users, much more focused on the usability of apps and their dissemination. Threema, for example, uses cryptographic primitives (the combinations upon which security protocols are built) numerically higher than any other instant messaging applicationbut it’s niche compared to other popular messaging apps.
The functions of Telegram
Telegram makes available (or has made available) before the competition many functions: groups of up to 200 thousand members and channels through which to reach an unlimited number of people. In addition there are the self-destructing messages (limited, however, to Secret Chats), a wide choice of emoticons and images to be included in conversations and the ability to send any type of file via chat, even large ones (up to 2 GB). To complete the picture, bots should be mentioned, automatic responders that satisfy specific requests.
All of this creates flexibility and has certainly contributed to the success of the app. The instant messaging applications they are pushed by users: the more people use them, the more popular they become. A messaging app whose use was not widespread among our contacts would be of little use.
In addition to that, Telegram e the API (Application Programming Interface) are open source (the code can be downloaded here)However, the server technology is not public. This means that, even when creating unofficial apps, the traffic generated by them will always pass through the company’s servers.
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How end-to-end encryption works
When using end-to-end encryption, messages and files are converted into unreadable text along the way from the sending device to the receiving device. The content of the chat will appear perfectly legible to the recipient, as it is encrypted using a secret key, that is a code created on both the sending and receiving devices. This is a code that is regenerated when each new message is sent, which is deleted when the decryption of the message is complete and which is not shared with the app (in this case Signal and WhatsApp) or with other devices.
In this way the messages, while being sent over the Internet and therefore technically hackableare readable only by the device that has the appropriate key.
End-to-end encryption is not only the prerogative of WhatsApp or Signal, to name the best known. All apps have this type of encryption system, including Telegram, even if only when using Secret Chats. The idea of having to manually activate a safety mechanism it can be at least unrealistic: messages sent in standard mode and protected by MTProto 2.0 are saved on Telegram servers and this, in terms of security, can be a flaw.
How MTProto 2.0 works
Created by Telegram, MTProto 2.0 is divided into two parts: the first dedicated to traditional chats, the cloud chats that are stored on the servers, uses a 256-bit AES encryption algorithm; the second is dedicated to secret Chats and is end-to-end and, in addition to the same algorithm, it uses one derived from RSA 2048 bit.
Unlike the end-to-end mode, which protects data from the sending to the receiving device, MTProto 2.0-based encryption protects the data according to a client-server and server-client logic, i.e. from the sender’s device to the Telegram servers and from there to the recipient’s device. In theory, the Telegram staff could read the messages stored on the servers and encrypted with MTProto 2.0. Only theoretically why the keys useful for decryption are stored on servers located in different countries and therefore underlying various legislatures. This also applies as the guarantee that Telegram undertakes not to grant access to user data to the authorities who request it.
Also cloud chat data they are stored on servers located in several countries and this, combined with the geographical distribution of the decryption keys, means that requests from the courts of several states are required to release user data to the authorities. In fact, Telegram points out that it has disclosed “0 bytes of data to third parties, including governments”.
Because Telegram doesn’t use end-to-end encryption by default
The conversation history is stored on the Telegram servers and can be retrieved by the registered users regardless of the device they use, peculiarities that end-to-end encryption does not conferbecause messages pass through the servers without being stored there.
Bottom line: is it safe or not?
Telegram began to carve out an audience as early as 2014, when also WhatsApp did not have end-to-end encryption, which was introduced in 2016. Its rise has been driven by the spread it has achieved, in turn induced by users who wanted to try alternative solutions when WhatsApp ran into problems.
Durov’s app has proved to be an optimal solution for those who do not want to be profiled by Meta and, although it does not present real security problems, it remains a perfect choice for instant messaging apps. However, this does not mean that Telegram is not safe, but only that its rise is the result of logics that take into account the preferences of users and, on top of these, the security item does not appear which (at this point wrongly) is always on everyone’s lips. But having one limited awareness.