This talk is about the iOS secure boot chain and how it changed throughout different iOS versions, while focusing on downgrading despite countermesures.
It will explain basics like what SHSH blobs and APTickets are and how IMG3 and IMG4 file format works.
Also a new technique called "prometheus" will be introduced which allows for the first time downgrading 64bit devices.
This Talk was translated into multiple languages. The files available for download contain all languages as separate audio-tracks. Most desktop video players allow you to choose between them.
Please look for "audio tracks" in your desktop video player.