identification permits to identify a a primary element (ie an entity or a relationship)
Identification is not authentication
Some systems use the last four digits of a Social Security number as an authentication code, even though a Social Security number is a public identification number. You can’t change it. You can’t prevent others from having it. It’s a unique identifier, but it’s hardly a secret: a good number to identify me by, but a terrible one to authenticate me by. Your mother’s maiden name is a similarly lousy authentication code.