Fast Digital Identity Revocation

The availability of fast and reliable Digital Identities is an essential ingredient for the successful implementation of the public-key infrastructure of the Internet. All digital identity schemes must include a method for revoking someone's digital identity in the case that this identity is stolen (or canceled) before its expiration date (similar to the cancelation of a credit-cards in the case that they are stolen). In 1995, S. Micali proposed an elegant method of identity revocation which requires very little communication between users and veri ers in the system. In this paper, we extend his scheme by reducing the overall CA to Directory communication, while still maintaining the same tiny user to vendor communication. We contrast our scheme to other proposals as well.