I think the 3GS and 4G encrypt in hardware. Also, you can set your phone to drop the key to wipe the phone if someone inputs the wrong PIN/password 10 times in

I think the 3GS and 4G encrypt in hardware. Also, you can set your phone to drop the key to wipe the phone if someone inputs the wrong PIN/password 10 times in a row. You don't have to worry about someone brute forcing it.