Techie ZONE

1. You need to use iTunes 11.0.5 or lower for this to work. If you already have iTunes 11.1 or above, then you’ll have to completely uninstall it. You can download iTunes 11.0.5 from Old Apps.
2. Download iFaith from GitHub and unzip it.
3. Connect your iPhone 4 to your computer.
4. Now If you know where your “SHSH blob” is and you have it saved locally then you’re ready and you can skip to the next section,if not you can use iFaith tolocate it. Double click the iFaith application and select 'OK' then choose show available SHSH caches on server. Click Yes and then choose Show list of available SHSH blobs on TSS servers.You’ll get a list of available blobs and you can downloadthe one you want.
5. When you’ve got it you can exit iFaith.

How to use iFaith to downgrade to iOS 6.

1. You should have your iPhone 4 connected to your computer.Start iFaith again and this time select Build 'signed' IPSW w/ blobs then Browse for SHSH blobs and select the one you want from wherever you saved it earlier. 
2. You’ll need the iOS firmware file next, but you can just select Download it. Once it’s ready you can continue and choose Build IPSW. This will take a while.. When it’s done make sure to note the name of the IPSW file it has created and then click OK to continue. 
3. You now need to put your iPhone into DFU mode. Hold the Sleep/Wake button on your iPhone andSlide to power off. Click Start on iFaith and follow the onscreen instructions to press and hold the Sleep/Wake key and the Home key for 10 seconds, then release the Sleep/Wake key and keep holding the Home key for 30 seconds.
4. You should see a message in iFaith telling you that your iPhone 4 is in DFU mode and you can click OK and then exit iFaith.