iPhone Could someone explain signed IPSW's?

Discussion in 'Jailbreaks and iOS Hacks' started by novice121, Apr 3, 2013.

  1. novice121 macrumors member

    Feb 15, 2013
    I'm a little confused about this "signed" firmwares by apple, which one work with blobs, which devices don't, and what exactly does a no longer "signed" firmware means?

    Sorrry for the noobish question, but reading elsewhere is not always clear.
  2. ECUpirate44 macrumors 603


    Mar 22, 2010
    What is your question specifically?

    Once apple stops signing a firmware, you must have your devices blobs saved for that firmware in order to revert back to it in the future.
  3. Tyler23 macrumors 603


    Dec 2, 2010
    Atlanta, GA
    And blobs do not work (as of now) on the iPhone 4S or iPhone 5. So for those two devices, there is no way to restore a firmware that Apple is no longer signing. Blobs are useful however for iPhone 4 and previous devices.

    Signed means that Apple is still verifying the firmware. They stop verifying a firmware soon after a new update is released. As of right now, if you need to restore an iPhone 4S or 5, there is no way to restore it to any other firmware other than 6.1.3.
  4. rgarjr, Apr 3, 2013
    Last edited: Apr 3, 2013

    rgarjr macrumors 603


    Apr 2, 2009
    Southern California
    Apple doesn't want people putting their idevices out of jail so they force you to install only the latest firmware which right now is not jailbreak-able.

    I think it's kind of dumb that they only allow you to install the latest FW. It's your device u should be able to install whatever firmware u like.

    I think before you just downloaded whatever IPSW file for your device and installed it. Now iTunes checks with Apple servers to only allow the latest FW to be installed.
  5. Tyler23 macrumors 603


    Dec 2, 2010
    Atlanta, GA
    I think they do it for a few reasons. I have nothing against Jailbreaking, but look at it from their point of view. If jailbreakers are able to find exploits, so are people that may attempt to maliciously attack iOS users. Apple is just like any other company that values security.

    Also, they may only allow the newest firmware to prevent jailbreaking, but I also believe it's because they want people installing the latest firmware which contains bug fixes and other improvements. It only makes sense that they'd want users using the latest software, that way they receive less complaints about user issues.
  6. Applejuiced macrumors Westmere


    Apr 16, 2008
    At the iPhone hacks section.
    It is something that is mentioned a lot throughout our jailbreaking community. “Make sure you save your SHSH Blobs before you update,” is a pretty common saying around these parts. We’ve been asked several times lately what it is.

    An SHSH Blob is basically what Apple uses to verify the version of iOS you are running. That’s why we tell you to save your SHSH Blobs before upgrading your firmware on your iDevice. Otherwise you might not be able to downgrade to a previous version in the event you needed to.

    That is unless you managed to save your SHSH Blobs with a program like TinyUmbrella. Doing so will allow you to trick iTunes, into thinking you are running an older version.

    Why can’t these SHSH Blobs just be downloaded like everything else?” Your SHSH Blob is device specific. It uses the ECID (Exclusive Chip ID) of your device, along with a challenge key, as part of the authentication process with Apple.

    Because that key is static (doesn’t change), and you’re using the same ECID, it is possible for you to save your own SHSH blob for later use. It can then be used to downgrade your iDevice if you accidentally update your firmware and there’s no jailbreak available.

    Now make sure you save you SHSH blobs. Currently useful for all non A5 devices but good to save even on iphone 5 and 4S models in case they can be used in the future.
  7. anonymust macrumors member


    Sep 20, 2010
    in a house
  8. AppleFanatic10 macrumors 68030


    Nov 2, 2010
    Hawthorne, CA
    This thread is like 2 years old, lol :D

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8 April 3, 2013