Apple ipod

Ipod touch downgrade help! I lost my personal IPSW?

I have an iPod touch, and I think it is 3G, I want to Cydia but the thirst that I have to give to 3.1.2 (Now 3.1.3) and when I click Restore, select a standard shift and 3.1.2 of the firmware downloaded, but when the checks, I get an error at the signing (of course) because my firmware is not personal. Now my question is, how I can restore to 3.1.2? (Not the apple on the Restore button, perhaps?) Courses third generation, turd, and can be called so stfu 3G turd who sent this in, of course, the third generation, listen Im just do it for my girlfriend and she really wants, so that please help me and do not say strange things.

No, you can not restore to 3.1.2 (not available) Apple has not signed the firmware of the week past expected Dev Team, working in 3G 3.1.3 jailbreak

Easy Jailbreak Firmware 3.1.2 iPhone 3G, 3GS and iPod Touch 1g, 2g, and 3g with BlackRa1n