IPhone 4 GSM iOs 6.1.2? SHSH Blobs Share?

Can anyone share this blobs? My friend was at 4.3.1 and my iPod was on 6.1.2. As the new os supported many source in Cydia so he wanted to update too. I wanted to updated to os 6.1.2 bcos realize 6.1.3 can't be jailbreak, but I found that Jailbroken iDevice will be very difficult to upgrade if not upgrade to the Current Firmware released in iTunes which is 6.1.3 but I also read many article about Easily Downgrade firmware to an older one.

I have read certain amount of info on the internet about upgrading and jailbreaking.
After I was at 6.1.3, and try to downgrade to 6.1.2 for the untethered jailbreak, I get too many error and kept on searching and finally found the issue about SHSH but it was way too late for me.
Because those so-called excellent hackers never mentions anything about backup the blobs.

You can't get blobs from another device to use on your own… That's not how it works.

Should have done some more research

You can atually