You can downgrade without SHSH?

[BiraNeto]

I know, this must be fairly common question, but again I ask. Is it possible to downgrade without having SHSH?

 

[Gerryboy]

I know, this must be fairly common question, but again I ask. Is it possible to downgrade without having SHSH?

Enlighten me please......what is shush I haven't a clue.

 

[Bosvaark]

Enlighten me please......what is shush I haven't a clue.

SHSH blobs is a Hash signature system (Signature HaSH blobs) made by Apple Inc. to control manual software downgrades on iPhones, iPads, and iPod touches (a typical prelude to Jailbreaking). An SHSH is created by an SHSH formula (CLI Application) with 3 or 4 TSS keys- the device (e.g. iPhone 4 CDMA), the firmware version being signed (e.g. 4.2.8) and the device's ECID- a unique ID contained within every device. The SHSH is a Plist, built with blobs, with each blob intended for a different part of the software (like kernel and Apple logo). These blobs control which firmware is restorable and which is not. When Apple wishes to restrict users' ability to "downgrade" their devices to a prior firmware version, Apple can simply refuse to generate this hash during the downgrade attempt, and the downgrade will not be successful (or at the very least, will require significant technical intervention).

 

[Bosvaark]

Should be as clear as mud now ;-)

 

[Mickey330]

Here's a good tutorial about SHSH blobs (written by my fellow moderator, f4780y): http://www.ipadforums.net/showthread.php?t=59291

It's a great read but the simple answer to the first question is no, you cannot downgrade without SHSH blobs if Apple has closed your destination iOS's signing window.

Hope that helps.

Marilyn