A blind credential is a token asserting that someone qualifies under some criteria or has some status or right, without revealing "who" that person is — without including their name or address, for instance. It is used in maintaining medical privacy and increasingly for consumer privacy. It can be quite difficult to ascertain that someone is not using another's credential — identity theft — therefore a great deal of effort goes into the application of cryptography to authentication. See also: Public key cryptography, Blind signature, Digital credential