Overview#

Anonymous Credential is a Credential created by a system a End-User entity uses uses a different "digital pseudonym" with each Service Provider.

Anonymous Credential was described in SECURITY WITHOUT IDENTIFICATION: TRANSACTION SYSTEMS TO MAKE BIG BROTHER OBSOLETE by DAVID CHAUM in 1985

Anonymous Credential can be thought of as a Digital Signature by the Issuer on a list of attribute-value pairs, e.g. the list

(fname=”Alice”, lname=”Anderson”, bdate=”1977/05/10”, nation=”DE”)

The most straightforward way for the User to convince a Verifier of her list of attributes would be to simply transmit her credential to the Verifier.

This approach has a number of disadvantages, most notably:

• that the User has to reveal all of her attributes so that the Verifier can check the Digital Signature;
• that the Verifier can reuse the credential to impersonate Alice wrt other Verifiers.

With anonymous credentials, the User never transmits the credential itself, but rather uses it to convince the Verifier that her attributes satisfy certain properties – without leaking anything about the credential other than the shown properties. This has the obvious advantage that the Verifier can no longer reuse the credential to impersonate Alice.

More Information#

There might be more information for this subject on one of the following:

• Digital Signature
• Identity Mixer

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• [#1] - SECURITY WITHOUT IDENTIFICATION: TRANSACTION SYSTEMS TO MAKE BIG BROTHER OBSOLETE - based on information obtained 2019-01-17-