The terrorists behind the Delhi blasts reportedly used the Telegram app to plan the attack. According to media reports, they relied on a special feature inside the app that ensured their conversations remained completely private and inaccessible to others.

Here’s the feature they used and how it works.

The Secret Feature Used: Telegram’s Secret Chat

Reports suggest that the attackers used Telegram’s Secret Chat feature, which offers far stronger privacy compared to normal Telegram chats. These chats are protected by end-to-end encryption, meaning only the two devices involved in the conversation can read the messages. No third party—including Telegram—can access the content.

This is one of the key reasons such apps are preferred by criminals: they keep communication hidden and extremely difficult to trace.

How Secret Chat Encryption Works

Telegram’s Secret Chat feature creates a secure, encrypted exchange between two devices. Key points include:

• Messages stay only on the sender’s and receiver’s devices
• Messages cannot be forwarded
• Screenshot alerts may be triggered in some cases
• All messages get automatically deleted after a set time
• Secret Chats work only 1-to-1, meaning group chats are not allowed

This combination of encryption and disappearing messages makes it nearly impossible for agencies to retrieve past conversations.

Why the Messages Disappear

The self-destruct timer in Secret Chats deletes messages after a chosen time—sometimes within seconds or minutes. Media reports indicate that even screenshots of the chats showed messages vanishing automatically. Once deleted, these messages cannot be recovered from any server.

What Experts Say

Cybersecurity experts point out that apps like Telegram are:
• Free
• Easily accessible
• Abundant (with many alternatives available)

Even if one app is banned or blocked, users quickly shift to another platform with similar encryption features.

Another major challenge for investigators is that the servers of apps like Telegram are located outside India, making it extremely difficult for authorities to access user data or chat logs during investigations.