does redsn0w alter 3.0 ipsw?

[B737]

when you point redsn0w to the ipsw located in application data folder>apple>itunes ect.... and it checks that file, does it modify the ipsw i pointed it to?

meaning, if i want to go back stock and use my original ipsw can i just use that one again? or has it been modified?

 

[Vandam500]

I am pretty sure it does not modify it.