My Passport Ultra and other encrypted drives

Can someone point me to any kind of WD document clearly stating that AES 256 is being used in the Passport drives?

I can only find the phrasing “256 bit hardware encryption” and the like.

Hello,

As a recommendation, try contacting WD Support directly.

Contact info: http://support.wd.com/contact/contact.asp?lang=en

WD Support claims it is AES 256, but no documentation does - also according to WD Support.

Why utilize something as good as AES and then not specify it?