Heck, I can't remember how old I am. Pretty sure I'm over 21 though, and most authorities would agree after a cursory visual inspection. There are also folks wh

Heck, I can't remember how old I am. Pretty sure I'm over 21 though, and most authorities would agree after a cursory visual inspection. There are also folks who: * Can only guess at the day, month, and/or year of their own birth. * Cannot currently tell you their date of birth (e.g. incapacitated, incommunicado, unconscious, absent, or forgot. what year is it?) * Cannot prove their date of birth (e.g. records destroyed) * Mix up their relatives date of birth (the probability of this approaches 1 asymptotically as the family size increases) * Use a different date format to you, with consequently ambiguous interpretation Similar impedance mismatches between information and permission exist in almost all authorization domains. Consequently, the only credentials with general applicability are those capable of asserting a right or validating a claim, not those that merely sign data.