The USB key mode uses a key stored on a USB flash drive for authentication.
For every startup, the USB flash drive must be connected to the computer.
USB key protection is used on Windows 7 endpoints if no TPM is available or if it is disabled via GPO.
The USB flash drive must be formatted with NTFS, FAT, or FAT32. The exFAT format is not supported. Furthermore, the USB flash drive must be writable.
If all conditions are met, the USB key protection installation dialog will be displayed and the user must select a connected USB flash drive that will be used to store the key.
The user can click Restart and Encrypt to immediately restart the computer and start encryption.