The Unexplained Unlock - How iPhone Unlocking Works?
Soon after the SIM unlock, a new hardware based unlock was brought into the market by an unknown commercial company, which reverse-engineered the original hardware unlock method. A few weeks later, DEV Team, after finding out how to get past the baseband security, released a free software based (programmatically complex) unlock for iPhone users.
How DEV team worked?
Being a smartphone, the iPhone is a pocket sized computer that contains two processors. One a fast speed processor for handling the Apple’s X O.S, a UNIX based operating system and the other being a low speed processor for handling phone features like calling, communication, etc. Some people refer to the second part of the CPU that holds the data as baseband or firmware.
Apple never wanted the iPhone to be used in other countries, except the US and had therefore applied a subsidy lock (your iPhone runs only with an authenticated service provider like AT&T).The baseband or firmware was designed in such a way that it could not be read or written by any software except iTunes and also iPhone was to be activated by iTunes only.
Initially, it was difficult to get past these security barriers, but after the hardware based unlock, DEV Team figured out how to get past the security and break into the baseband to unlock the iPhone. Unlocking an iPhone often called jailbreaking is a simple process in comparison to SIM unlock, which requires a lot of effort.
To unlock a SIM, DEV team had to get past the CPU chip and the baseband chip, which means data loaded into the baseband chip had to be digitally signed by Apple; otherwise, the entire process would fail. However, DEV Team got their hands on the digitally signed encrypted Apple key, which they have been using to design simpler versions of iPhone unlock.
Quick Overview of Unlock Process
Boot iPhone into recovery mode. Dump and rewrite the existing firmware with the modified version.
- Manually execute the command to unlock iPhone
- Reboot iPhone.