I decided to sell my jailbroken iPhone 4. I backed up my SHSH's 4.0.1 via Cydia. On the Cydia homepage it says my SHSH's are on file for 4.0.1 and 4.0.2. Can I still do a complete reset-erase all content and settings before I sell? Would the buyer be able to re-jailbreak the phone? Thanks!