What Is USB Restricted Mode?
USB Restricted Mode is a new setting that disables data access to an iOS device through the USB port if the device has been locked for an hour or more.
This doesn’t just apply to connections to a computer using a Lightning cable.
How Do You Enable USB Restricted Mode
Go to Settings and check under Face ID (or Touch ID) & Passcode, you will see a new toggle for USB Accessories. By default, the switch is off. This means that once your iPhone or iPad has been locked for over an hour straight, iOS will no longer allow USB accessories to connect to the device — shutting out cracking tools like GrayKey as a result. If you have accessories that you want to continue working after your iPhone has been sitting locked for awhile, you can toggle the option on to remove the hour limit.
Apple’s wording is a bit confusing. You should leave the toggle disabled if you want your iPhone to be most secure.
Apple’s decision to implement USB Restricted Mode is a boost to user privacy, but might again put the company at odds with law enforcement and authorities who want to access information stored on recovered or confiscated iPhones.