Downgrading iPhone 4 from iOS 7

The iPhone 4 can be downgraded to any firmware if you have the valid SHSH and aptickets. It might seem like a very simple thing to do, but the information on how to do it on a Mac is scattered around all over the web and all of the below steps are necessary.

1. Build a signed IPSW using iFaith
1. Download iFaith from http://ih8sn0w.com "Note: This step can be performed on windows in VMware"

2. Get your SHSH blobs ready Tinyumbrella stores the SHSH blobs in ~/.shsh/

3. Build your firmware with iFaith and the blobs

2. Downgrade iTunes to 11.0.5
Since iTunes 11.1 Apple prevents downgrades, therefore you have to downgrade iTunes to 11.0.5. More details can be found here: http://blog.ih8sn0w.com/2013/09/some-updates.html

1. You can download iTunes 11.0.5 from http://www.icj.me/ios/iTunes

2. Use pacifist (http://www.charlessoft.com) to install the old version (Default installer won't let you)

3. Put your iPhone 4 into pwned DFU mode
To actually restore the signed IPSW your iPhone 4 has to be in the pwned DFU mode. The version of redsn0w I have been trying to use did not work, therefore I recommend using ih8sn0w's iReb: http://ih8sn0w.com

It is available for OS X and windows.

"Note: This step cannot be performed in VMWare"

4. Restore the signed IPSW
Once your iPhone 4 is in pwned DFU mode, simply start iTunes and alt-click the restore button. Select the signed IPSW and it should work.

"Note: This step cannot be performed in VMWare"