Entitled odysseusOTA, the command line tool takes advantage of the fact that Apple is still signing the OTA (over the air) firmwares for iOS 6.1.3 on the iPad 2 and iPhone 4s. Want to see the downgrade in action? Then watch this detailed step-by-step video.
The downgrade method is the work of developer tihmstar, with additional credit going to winocm (kloader), pod2g (odysseus), and iH8sn0w (consulting) among others.
Obviously this downgrade method will have extremely limited use-case scenarios, as it is strictly limited to the aforementioned firmware/hardware combos. Nonetheless, it is an impressive (no SHSH blobs needed!) feat, when you consider how difficult Apple makes it to downgrade firmware these days.
What do you think ?