It looks like Camenisch & Lysyanskaya are patenting their credential system. This is from the online patent applications database: http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=/netahtml/PTO/search-bool.html&r=1&f=G&l=50&co1=AND&d=PG01&s1=camenisch&OS=camenisch&RS=camenisch
Non-transferable anonymous credential system with optional anonymity revocation
Abstract
The present invention relates to a method and system for securely proving ownership of pseudonymous or anonymous electronic credentials. A credential system is described consisting of users and organizations. An organization knows a user only by a pseudonym. The pseudonyms of the same user, established for use with different organizations, cannot be linked. An organization can issue a credential to a pseudonym, and the corresponding user can prove possession of this credential to another organization that knows him under another pseudonym. During the prove of possession of the credential nothing besides the fact that he owns such a credential is revealed. A refinement of the credential system provides credentials for unlimited use, so called multiple-show credentials, and credentials for one-time use, so called one-show credentials.
Some of the claims seem a little broad, like this first one:
1. A method for establishing a pseudonym system by having a certificate authority accepting a user as a new participant in said pseudonym system, the method comprising the steps of: receiving a first public key provided by said user; verifying that said user is allowed to join the system; computing a credential by signing the first public key using a secret key owned by said certificate authority; publishing said first public key and said credential.
Wouldn't this general description cover most proposed credential systems in the past, such as those by Chaum or Brands? Does anyone know how to contact the PTO regarding proposed patents, perhaps to point out prior art?