Dev Team: Apple Has Started ‘Soft’ SHSH Blob Checks With iOS 4

Jailbreak iOS 4 on iPhone 3GS

iPhone Dev Team has just reported that with iOS 4 or higher, Apple has started putting ‘soft’ SHSH blob checks in the firmware.

This means that like iPhone 4 and iPhone 3GS, if iTunes can’t get the SHSH blobs for iPhone 3G or iPod Touch 2nd generation (due to signing window being closed), the iTunes restore will error out.

According to Dev Team, soft SHSH blob check can be easily bypassed by using Redsn0w and PwnageTool.

Cydia has also started saving the SHSH blobs for iPhone 3G and iPod Touch 2G.

Dev Team reports:

Those of you with jailbroken iPhone3G and ipt2G devices may now have noticed Cydia starting to save your SHSH blobs too, just like it does for iPhone3GS, ipt3G and later devices. That’s because starting with 4.0, Apple started putting a “soft” SHSH blob check in the firmware. The SHSH blob check is very real in the sense that if iTunes can’t get your blobs (because the Apple signing window has closed), the iTunes restore will error out. But it’s “soft” in the sense that those devices can always use redsn0w or PwnageTool to get past the error (the bootroms themselves for those devices don’t require blobs to be in the firmware files, unlike the newer bootroms).

So, Cydia is doing this to allow you to continue to use iTunes to restore to 4.x on iPhone3G and ipt2g outside of Apple’s signing window without needing to use redsn0w or PwnageTool to get around Apple’s annoying new restriction.

So if you were wondering why Cydia has started storing SHSH blobs for your iPhone 3G or iPod Touch 2G, this should answer the question.

[via Dev Team’s blog]