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

Medical privacy

The main subject of medical privacy or health privacy is the 'medical record' which historically has been a paper file of the entire medical history of the patient. Various electronic forms of medical records have existed in western countries, but mostly in an unintegrated fashion. This lack of...

 and increasingly for consumer privacy

Consumer privacy

Consumer privacy laws and regulations seek to protect any individual from loss of privacy due to failures or limitations of corporate customer privacy measures...

.

It can be quite difficult to ascertain that someone is not using another's credential

Credential

A credential is an attestation of qualification, competence, or authority issued to an individual by a third party with a relevant or de facto authority or assumed competence to do so....

 — identity theft

Identity theft

Identity theft is a form of stealing another person's identity in which someone pretends to be someone else by assuming that person's identity, typically in order to access resources or obtain credit and other benefits in that person's name...

 — therefore a great deal of effort goes into the application of cryptography

Cryptography

Cryptography is the practice and study of techniques for secure communication in the presence of third parties...

 to authentication

Authentication

Authentication is the act of confirming the truth of an attribute of a datum or entity...

.

Electronic money

Electronic money

Electronic money is money or scrip that is only exchanged electronically. Typically, this involves the use of computer networks, the internet and digital stored value systems...

 requires some blind credential system to assert that the money is valid, has not been already spent, and belongs to the individual or entity that is spending it.

It is usually not wise to consider a blind credential outside of the Public Key Infrastructure

Public key infrastructure

Public Key Infrastructure is a set of hardware, software, people, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates. In cryptography, a PKI is an arrangement that binds public keys with respective user identities by means of a certificate...

 of electronic identity guarantees required to support it.

See also: Public key cryptography, Blind signature

Blind signature

In cryptography a blind signature as introduced by David Chaum is a form of digital signature in which the content of a message is disguised before it is signed. The resulting blind signature can be publicly verified against the original, unblinded message in the manner of a regular digital...

, Digital credential

Digital credential

Digital credentials are the digital equivalent of paper-based credentials. Just as a paper-based credential could be a passport, a Driver's license, a membership certificate or some kind of ticket to obtain some service, such as a cinema ticket or a public transport ticket, a digital credential is...