Redsn0w 0.9.11b1 Released, Downgrades A5 Devices

Following the release of iOS 5.1.1 earlier this week, the iPhone Dev-Team has released an update to redsn0w for OS X and Windows, bringing the popular jailbreaking utility to version 0.9.11b1. The update includes support for restoring A5-powered devices, giving iPhone 4S, iPad 2, and new iPad users a long-awaited method of downgrading their device’s iOS version.

Redsn0w 0.9.11b1 takes a “radical departure” from previous versions, as this new method of downgrading A5 devices involves a new hack that does not require a bootrom-level exploit. In fact, this new method actually upgrades your device to the latest iOS version before downgrading to the older version you desire.

Interestingly, the iPhone Dev-Team says that Apple is aware of this issue, but has yet to fix it. Apple can address the issue with a firmware update at any given time. The team also warns iPhone users who unlock their phones to avoid using this new method, since it will update your device to the latest baseband. Read on for some important information about redsn0w 0.9.11b1.

While iOS hacker pod2g is working on a jailbreak for these devices, which he may hold off on releasing until the launch of iOS 6, downgrading your device could be a viable option if you wish to use the iOS 5.0.1 untethered jailbreak in the meantime. Keep in mind the following notes with this latest version of redsn0w:

Some important points:

  • The new feature is at Extras->Even More->Restore
  • You cannot downgrade without the personalized SHSH blobs for your device at that lower firmware.  You need to have fetched those blobs while the signing window was open, using either Cydia’s built-in TSS@Home feature, or with TinyUmbrella.  The new Restore screen of redsn0w lets you choose either the remote blobs or local ones (for the earlier firmware).  If you don’t know where TinyUmbrella put your blobs, TinyUmbrella has a button that will show you (copy them out of that folder and feed them to redsn0w).
  • The A5 downgrade method actually updates to the latest firmware before downgrading to the earlier one. This process updates your baseband to whatever is newest.  DO NOT USE THIS METHOD IF YOU RELY ON UNOFFICIAL UNLOCKS of your iPhone4S.  Those who used the temporary SAM technique to unlock their iPhones to specific SIMs shouldn’t be affected by this baseband update.
  • This method can be fixed by Apple with a firmware update.  It’s a (pleasant) mystery why they haven’t fixed it yet, because reverse-engineering of the restore ramdisk indicates they do know about it.  It’s possibly too niche to bother to fix right now.
  • The least-tested devices with this method are the iPad2,3 and iPad3,2 (because we don’t have those models).  If you do and you feel like experimenting, please let us know how it turns out in the comment section below!
  • This update involves a bunch of new redsn0w code.  We recommend sticking to the previous version 0.9.10b8b unless you’re specifically using this new feature, until all the bugs are worked out!  (Note: If redsn0w gets stuck at the “Waiting for device” stage for more than 30 seconds, you’ve hit a pesky GUI bug…that will be fixed in an upcoming version!)

Those with an iPhone 4S, iPad 2, or new iPad will need to have the SHSH blobs saved for the desired iOS version that they wish to downgrade to. TinyUmbrella or Cydia can be used to save your device’s SHSH blobs, so long as Apple is still signing them. That means anyone who purchases one of these A5-powered devices with iOS 5.1 or 5.1.1 pre-installed will not be able to downgrade to iOS 5.0.1 or earlier.

Jailbreaking allows you to install third-party applications, tweaks, mods, themes, useful utilities, and other content — called “packages” — from Cydia, the jailbreak equivalent of the App Store on iOS. Jailbreaking essentially allows for you to further customize and enhance your iPhone, iPod touch, or iPad beyond the limits that Apple imposes.

[iPhone Dev-Team]

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