Thanks. This explains it. I was just thinking about my old Thinkpad X41. That had TPM module and hardware encryption. There's nothing that IBM or the TPM manufacturer could've done to decrypt it (unless the TPM module already had backdoors, haha). Latest iPhones are basically the same?
iTunes recovery mode? It allows to restore the OS, but also gives you other means to manipulate the device. Imagine if they simply hot-patch the lockscreen to allow any number of tries of password?
