Practical Traceable Anonymous Identification

Internet privacy is of increasing interest, since online services are getting more and more ubiquitous and cover many aspects of one’s daily life. Hence users leave information tracks and disclose information during usage of services which can be compiled by third parties to infer users behavior, preferences etc. and thus may violate user’s privacy. In this paper we propose a practical method for traceable anonymous identification which can be used for online services in order to protect user’s privacy. It enables users to authenticate themselves to a service provider, whereas the service provider is not able to identify authenticating users. However, the service provider can be sure that only authorized users are able to authenticate. Since absolute anonymity may open the door for dishonest behavior, our protocol incorporates traceability, which enables a service provider to identify authenticating users in cooperation with an offline trusted third party. The proposed method is fully compatible with real world scenarios, i.e. public key infrastructures based on X.509 certificates, and can be easily deployed using state of the art smart cards. Furthermore, the proposed method is very efficient and we give a performance analysis as well as a security analysis of the introduced protocols.