My confusion with SHSH and "Older" versions

[Overseer]

OK, first things first, I'm on a totally normal working 4.1 Jailbreak on my iPod touch 4G. I ONLY have the SHSH blobs from 4.2.1 saved because I got it for christmas so missed the older SHSH window...

I do however have some firmware from my old iPod however, including my iOS 4.2b3 firmware which as far as I'm aware is necessity to jailbreaking your iPod touch at 4.2.1.

My questions are:

1. Where do the SHSH blobs come from, the device or apple?
2. If I were to restore to iOS 4.2b3 on my iPod, for starters could I do so now, and if I can, would I be able to save SHSH blobs for it now?

Thanks in advance,
Overseer

 

[myzhi]

SHSH files are unique to each device and firmware. So, you can use them on a different device or firmware. And, the latest one is sent out everytime you do a restore from Apple. It has nothing to do with what firmware is currently on the device.

 

[iRandom]

1. SHSH Blobs are a "signed" part of the firmware. Apple only signs the latest firmware on their servers so you must save your SHSH blobs of your current version firmware if you wish to upgrade to the latest to be able to downgrade back again.

2. If you do not have the iOS 4.2.1b3 SHSH blobs saved, then you won't be able to downgrade.