Telegram introduces disappearing images and encrypted CDNs

Chatapp Telegram has announced new features that are part of version 4.2 of its app. For example, the service introduces disappearing photos and videos into regular chats and now uses encrypted content delivery networks for popular media.

The service reports that in the new version, users can add a “self-destruct timer” to images and videos that they share with others. As a result, they disappear after a certain period of time. This feature is not entirely new to Telegram, for example, it was already possible within encrypted secret chats to ensure that media disappears over time. In addition to this change, Telegram has updated the photo editing tool.

Telegram also announces that it will use secure content delivery networks starting with version 4.2. The company explains that these are used for popular media files that are shared in very large public chat groups with more than 100,000 participants. It uses separate data centers for this, which, however, are not part of its own infrastructure and should therefore be treated as ‘hostile territory’.

These data centers are used in areas where there is a lot of Telegram traffic but where the service does not want to place its own servers ‘for obvious reasons’. Because these data centers are close to users, they should be able to offer faster download speeds. All media sent to the data centers is encrypted, according to Telegram. It therefore invites researchers to examine the open source source code of the implementation. The files are encrypted by the Telegram server with 256bit AES and the cdn data centers should not be able to access the media. The user gets the decryption key directly from the Telegram server.

CDN operation, explained by Telegram