A First Approach to Provide Anonymity in Attribute Certificates

Abstract

Abstract. This paper focus on two security services for internet applications: authorization and anonymity. Traditional authorization solutions are not very helpful for many of the Internet applications; however, attribute certificates proposed by ITU-T seems to be well suited and provide adequate solution. On the other hand, special attention is paid to the fact that many of the operations and transactions that are part of Internet applications can be easily recorded and collected. Consequently, anonymity has become a desirable feature to be added in many cases. In this work we propose a solution to enhance the X.509 attribute certificate in such a way that it becomes a conditionally anonymous attribute certificate. Moreover, we present a protocol to obtain such certificates in a way that respects users' anonymity by using a fair blind signature scheme. We also show how to use such certificates and describe a few cases where problems could arise, identifying some open problems.

Architecting Adaptable Security Infrastructures for Pervasive Networks through Components

“…An elegant solution to enhance the PMI with anonymity services is proposed in [12]. X.509 ACs are extended into anonymous attribute certificates (AAC), the link between identities and attributes being based on pseudonyms.…”

“…A TTP guarantees the secrecy of the link between real identities and pseudonyms, but may disclose the identity of the certificate holder under some particular conditions. The scheme described in [12] is based on fair-blind signatures. AACs may also be based on other types of signature schemes [11] such as group signatures [13].…”

A reference model for Authentication and Authorisation Infrastructures respecting privacy and flexibility in b2c eCommerce

“…These certificates could carry authorisation information as well as certify a pseudonym. A protocol to obtain such certificates is given in [1].…”

The SPARTA Pseudonym and Authorization System

“…Despite the great scientific interest in privacy-preserving approaches, to date only a limited effort has been spent to adapt such approaches to operate with existing and widely deployed standards (see e.g. [7] for a standardbased approach relying on X.509 Attribute Certificates).…”