AES EME mode (two layers of 'lightweight mixing' in between) ; some different modes we don't really get to talk about a lot when it comes to AES encryption.
This specific 'mode' of AES comes with a security proof.
http://seclab.cs.ucdavis.edu/papers/eme.pdf
BY LibreCryptography
To pay the bills, Mr. Durov is issuing investors $1 billion to $1.5 billion of company debt, with the promise of discounted equity if the company eventually goes public, the people briefed on the plans said. He has also announced plans to start selling ads in public Telegram channels as soon as later this year, as well as offering other premium services for businesses and users.
Telegram is a free app and runs on donations. According to a blog on the telegram: We believe in fast and secure messaging that is also 100% free. Pavel Durov, who shares our vision, supplied Telegram with a generous donation, so we have quite enough money for the time being. If Telegram runs out, we will introduce non-essential paid options to support the infrastructure and finance developer salaries. But making profits will never be an end-goal for Telegram.
LibreCryptography from ca