Unique id could be something as silly as
sha256(concatenate(full-name,date-of-birth,place-of-birth))
Again, a fingerprint or an image of a retina is a signature or password not an id or username.
Unique id could be something as silly as
or just any unique number, like cell phone number.Again, a fingerprint or an image of a retina is a signature or password not an id or username.