Question Where is the iOS Signature in the .IPSW file?

[muhammad-124]

Hi all,
I want to downgrade an iPhone 4 from iOS 7.1.2 to iOS 6.1.3. I've unzipped both IPSWs and can see everything inside, but I don't know what the signature is called. My plan is to swap the signatures. Can anyone help?
Thanks!

 

[COLGeek]

I am pretty sure that will not work. Why are you doing this? What do you expect to gain?