I am planning on updating to iOS4 in the near future, but before I do, I need a little help with SHSH blobs. While 3.1.3 was still being signed, I saved my SHSH blobs locally using the Umbrella application. Since then, my computer has been refurbished (wiped absolutely clean due to an aggressive virus). So if I need a file that was previously on my computer, it's not going to be there. However, Cydia tells me that "This device has SHSHs on file for iPhone OS: 3.1.3". My question is: Does this mean I am still capable of downgrading if I were to update to 4.0? And if so, what method would I go by?