Digital cash token protocols use a combination of blind digital signatures and pseudonym authentication with at least two pairs of public and private keys. A user is provided with one master pair of private and public keys and as many pseudonym pairs of private and public keys as desired. The resulting...http://www.google.com/patents/US7877331?utm_source=gb-gplus-sharePatent US7877331 - Token based new digital cash protocols with combined blind digital signature and pseudonym authentication
