Is Telegram Really Encrypted? A Deeper Look Into Its Protocol

Telegram has grown immensely popular, especially among users who value privacy and security. The app touts itself as a secure messenger, but what does that really mean? Is Telegram truly encrypted, and if so, how secure is it? This article delves into these questions, drawing on the expertise of cryptography expert Matthew Green, a renowned professor at Johns Hopkins University.

Understanding Encryption in Messaging Apps

Before we dive into Telegram’s encryption, it’s important to understand what encryption means in the context of messaging apps. Modern private messaging services often use end-to-end encryption (E2EE), which ensures that only the sender and the recipient can read the messages. Even the service provider (in this case, Telegram) cannot decrypt these messages because they do not hold the decryption keys. This level of encryption is considered the gold standard for privacy and security in communication.

Telegram’s Approach to Encryption

Telegram uses a custom encryption protocol called MTProto. According to Telegram, this protocol is designed to secure the communication between clients (users) and servers. However, this is where things start to get complicated.

Telegram does not use end-to-end encryption by default for all messages. Instead, it relies on server-client encryption for its standard chats. This means that while messages are encrypted between your device and Telegram’s servers, Telegram still has the ability to decrypt and read them. This approach is fundamentally different from the more secure end-to-end encryption used by other messaging apps like Signal and WhatsApp, where even the service provider cannot read the messages.

If you want true end-to-end encryption on Telegram, you have to manually enable a feature called Secret Chats. This feature is only available for one-on-one conversations, not for group chats. As Matthew Green points out in his analysis, this is a significant drawback: "The practical impact is that the vast majority of one-on-one Telegram conversations — and literally every single group chat — are probably visible on Telegram’s servers."

The Challenges with Telegram’s Secret Chats

Even if you choose to use Secret Chats, there are limitations. For one, Secret Chats are device-specific, meaning that if you start a Secret Chat on your phone, you can’t continue it on your tablet or computer. Additionally, the process to enable a Secret Chat is not straightforward. It requires multiple steps, which may discourage less tech-savvy users from enabling this feature.

As Green notes, "Activating end-to-end encryption in Telegram is oddly difficult for non-expert users to actually do." This complexity contrasts sharply with apps like Signal, where end-to-end encryption is always on and requires no special setup.

The Security of Telegram’s MTProto Protocol

Telegram’s custom MTProto protocol has been subject to scrutiny by cryptographers. The protocol uses 2048-bit Diffie-Hellman key exchange, a method that allows two parties to establish a shared secret key over an insecure channel. While this sounds secure, Green and other experts have raised concerns about the implementation details. For example, the protocol relies on the server to choose certain cryptographic parameters, which introduces potential vulnerabilities if the server is compromised.

Moreover, MTProto uses a unique encryption mode called Infinite Garble Extension (IGE), which is not widely adopted in the cryptographic community. This choice of encryption mode has raised eyebrows among experts, who typically prefer more standard and thoroughly vetted approaches.

In Green's words: "Every place I put a ‘*’ in the paragraph above is a point where expert cryptographers would, in the context of something like a professional security audit, raise their hands and ask a lot of questions." In other words, while MTProto might be secure in theory, the unconventional choices and lack of transparency make it difficult to fully trust.

What About Metadata?

Even if Telegram’s encryption was flawless, there’s another aspect to consider: metadata. Metadata includes information about who you are talking to, when, and for how long. This data is not protected by end-to-end encryption and can be extremely valuable to third parties, including advertisers and governments.

As Green points out, "One of the biggest privacy problems in messaging is the availability of loads of meta-data — essentially data about who uses the service, who they talk to, and when they do that talking." This information can be stored on Telegram’s servers and potentially accessed by anyone with the right tools or legal authority.

Comparing Telegram’s Encryption to Other Platforms

When comparing Telegram to other messaging platforms, its security measures fall short in several areas. For example, Signal uses end-to-end encryption by default for all messages, including group chats. WhatsApp also offers end-to-end encryption by default, although it has other privacy concerns related to its parent company, Meta.

Telegram’s approach, which requires users to manually enable Secret Chats for end-to-end encryption, is less secure. Most users are unlikely to go through the effort of enabling this feature, leaving their conversations vulnerable to potential breaches.

The Legal Landscape: US vs. Europe

The way Telegram handles user data and encryption is also influenced by the legal environments in different countries. In the United States, companies are often required to comply with subpoenas that demand access to user data, including messages stored on servers. Since Telegram does not use end-to-end encryption by default, it could theoretically hand over the content of messages to law enforcement.

In contrast, Europe has stricter privacy regulations, such as the General Data Protection Regulation (GDPR). However, even in Europe, the metadata associated with Telegram users can be collected and stored, posing privacy risks.

Is Telegram Truly Encrypted?

So, is Telegram really encrypted? The answer is yes, but with significant caveats. While Telegram uses encryption, it does not employ end-to-end encryption by default for all messages. This means that Telegram itself can access most of the messages sent through its platform. If you want true end-to-end encryption, you must manually enable Secret Chats, a feature that is not available for group conversations and is cumbersome to activate.

In the end, Telegram’s claim as a secure messenger is questionable. As Matthew Green suggests, the app’s approach to encryption is far from industry-standard and leaves much to be desired in terms of user privacy and security. If encryption and privacy are your primary concerns, you might want to consider alternatives like Signal, which offer end-to-end encryption by default without the need for additional steps.