Telegram's official application is completely secure. It does not include advertising or any kind of spyware. Therefore, by installing Telegram, we are not compromising, in any way, our device's or our data's integrity. This is because the source code is available to any developer and can be audited.
However, beyond the fact that the Telegram application is secure, it is interesting to ask whether the service offered is also secure. So, is our information secure when using Telegram? The answer is yes. In fact, the company claims to offer higher security levels than its direct competitors, such as WhatsApp or Line.
The information transmitted through the Telegram servers is encrypted with a 256-bit AES system. In normal chats and groups, the encryption is a client-server type. It means that Telegram knows the decryption key. However, if you need more privacy, you can use the secret chats that add end-to-end encryption. In the latter case, the key is stored on the devices involved and the chat content can only be accessed through them.
Also, Telegram offers two-factor, or two-step, verification to log in. This way, when we enter our credentials in a new device, we can only continue if we enter a key that we will receive by Telegram or SMS. With this system, it is very difficult for an unknown person to enter our account.
Finally, we must clarify that although Telegram is secure, content circulating through Telegram may be unsafe or put our information or device at risk. Because the service supports sending any type of file, if we access certain channels or groups, we may end up downloading some dangerous content. That is why, although Telegram as an application and as a service is safe, we must proceed with wisdom and download only those documents that we trust completely.