Hacker Sheriff Hashim, a tool Ultrasn0w for anloka proved not so experienced what many thought and, increasingly, people began to treat problems restoring your phone c firmware 4.2.1. And this is the second biggest complaint about Ultrasn0w. Trying to reconcile his guilt, Hashim tried to explain briefly the rollback process for the firmware 1: 4.
The first step for this operation with the 3GS so this saved certificates SHSH on iOS 4.1.
And PwnageTool for Mac users:

