Because of the many problems associated with the new platform iOS 6, some iPhone or iPad users plan downgrade the new Apple iOS firmware to the previous iOS 5.1.1 version. Roll back the operating system from iOS 6 to iOS 5.1.1 is not too difficult. The only thing is that there are two conditions for the success of this process - the gadget on the chip A4 (iPhone 4, 3GS and iPod touch 4G) and the availability of the stored certificates SHSH blobs for iOS 5.1.1, as most recently Apple stopped signing the firmware.
How to downgrade from iOS 6 for iOS 5.1.1 for A4 devices
Step 1: Download RedSn0w 0.9.14b2 for Windows and Mac OS X.
Step 3: Make a backup copy of the contents of the mobile device via iTunes or iCloud.
Step 4: Run Redsn0w and connect the device to your computer via USB. Set the device to iOS 6 into mode DFU. To do this, hold the lock button for 3 seconds. Without releasing the lock, press the Home button for 10 seconds. Hold the Home button, release the lock. Continue to hold the button for 30 seconds.
Step 5: From RedSn0w, click the button Extras, then SHSH blobs, and then Stitch.
Step 6: You will see three options: IPSW, Local and Cydia. Click on the button and select Redsn0w IPSW firmware iOS 5.1.1, you downloaded in step 2.
Step 7A: If you have saved SHSH locally, click Local Redsn0w and select the file. Plist with a digital certificate for your device. Skip Step 7B.
Step 7B: If the certificate is stored in Cydia, click Cydia, then the program will create a new file with the IPSW-filed certificate. The file you want to use to restore from iTunes.
Step 8: In RedSn0w back two pages back and click Pwned DFU. This feature will help to put the device in Pwned DFU mode to install the firmware. Without it, the iTunes error 1600 will appear.
Step 9: Open iTunes, which will report that your iDevice is in recovery mode. Hold down the Option (Alt) on Mac or Shift on Windows, click Restore. Select the file you created in Redsn0w.
Step 10: At this point, iTunes will automatically install the iOS 5.1.1 firmware on the gadget. Wait until the operation is complete.
Step 11: Upon completion in iTunes, you may receive an error (-1). In this case, open RedSn0w and click Extras -> Recovery fix. Place your device into DFU mode, the recovery fix should run smoothly
Step 12: That is all, congratulations, you did downgrade iOS 6 on iOS 5.1.1!
Now you can jailbreak iOS 5.1.1. You can make it by downloading Absinthe 2.x for Windows, Mac OS X or Linux, which makes it one click untethered jailbreak for iOS 5.1.1. Simultaneously on the device appears store third-party apps Cydia. Absinthe is also available in addition to Redsn0w and Sn0wbreeze, and for special extreme – Command Line Interface CLI.