If you are writing a report or conducting research, the most useful "paper" is technically the , as it documents the hardware flaw that makes downgrading the A7 chip possible today, years after the signing window closed.
Based on the technical literature above, here is the current status of : iphone 5s ios 7 downgrade
To downgrade an iPhone 5s today, you rely on "nonce collision" or "checkm8" based exploits. The following technical papers/write-ups are essential reading for the method: If you are writing a report or conducting
Before diving into the how-to, it's essential to understand why one might want to downgrade: iphone 5s ios 7 downgrade