Signed IPSW files can be restored via iTunes. Unsigned IPSWs cannot currently be restored via iTunes.
✗ | iPod touch 3 | iPhoneOS 3.1.1 (7C146) | 17th September 2009 | 312 MB | iPod3,1_3.1.1_7C146_Restore.ipsw |
✗ | iPod touch 3 | iPhoneOS 3.1.1 (7C145) | 4th September 2009 | 312 MB | iPod3,1_3.1.1_7C145_Restore.ipsw |