|
The iPhone Wiki is no longer updated. Visit this article on The Apple Wiki for current information. |
Bluefreeze
iFaith has a protection that you don't use it on the wrong firmware to protect you. Bluefreeze modifies the firmware version (and firmware checksum) in the iFaith certificate file, so that this check gets disabled. By doing so, you can install any firmware version on your device, even without having saved the SHSH files. The problem by doing so is that you actually install a firmware without signatures.
Having an unsigned firmware installed won't let you boot of course. But using the limera1n exploit (DFU mode, then using redsn0w) you can still boot your device up. The problem is only that you have to repeat this every time, so it's not a real downgrade you would want for having an untethered jailbreak.
And also after boot, once you put the device to sleep, the kernel will notice LLB is invalid and reboot again. So you have to do all the procedure again. You can install a Cydia tweak called Prevent Sleep to avoid the device going to sleep.
This way a "downgrade" to iOS 4.3, 4.3.5, or 5.0 from 5.0.1 is poassible. Supported devices are iPhone 3GS, iPod touch 3G, and all A4 devices.
Purpose
With this method you can install a firmware for which you don't have SHSH saved for some tests, for examle if you're a software developer and need to do some tests on a specific version.
