Saved SHSH Blob Restores almost at an end?
MuscleNerd has tweeted several messages in the last hour which signal that the golden age of SHSH Blob replay attacks may be nearing an end.
After iOS5 is released it looks as though it will no longer be possible to save new SHSH Blobs and play them back to iTunes to fool it into restoring a previous firmware which is no longer being signed.
Whilst restores of 4.x and 3.x should still work if you have saved blobs and a supported version of iTunes (e.g. 10.3), new 5.x blobs will not be of use if you save them away and try and use them later.
According to MuscleNerd Apple is introducing a "number used once" (nonce) to the signing window just as they do for the baseband at the moment which will defeat the replay attack which is currently exploited to allow saved Blobs to work.
Sad news indeed. This will make it even more important to take great care with your upgrades / restores / and installs when jailbroken OR when waiting for a jailbreak!
If you install something old / incompatible with your device and have to restore you could be in for a world of pain if the "current" firmware is not jailbreakable... :(