&gt;This kind of attack is devastating for Telegram<p>Security flaws are found with any software on a regular basis. To say that it will &#x27;devastate&#x27; a project is completely blown out of proportion. The first TrueCrypt had a lot of flaws and it still were to become the most popular encryption software. The whole point of updates is that something can be improved when flaws are found.<p>&gt;For WhatsApp, everything is end to end encrypted by 
default, so the attacker doesn&#x27;t get any message history. All of the contacts for the MITM&#x27;d user also get a notice that their contact&#x27;s security code changed, and a comparison will fail to match. This is exactly what E2E was built to protect against.<p>All of this &#x27;safety&#x27; is rendered false hope when we can&#x27;t conclude that WhatsApp isn&#x27;t backdoored. Trusting a closed source project by Facebook is completely nonsensical imo.