It’s required to lock and unlock it, too.

The drive offers optional 256-bit AES hardware encryption, but a Mac or Windows utility is necessary to password protect the contents of the SSD. That’s not ideal for a mobile drive like the My Passport SSD. This offers backups, but the utility is designed around scheduling these on a regular basis, which assumes the drive will be constantly attached to your computer. Western Digital pre-loads onto the drive its WD Discovery software for macOS and Windows.