Accountable privacy based on publicly verifiable secret sharing

As developing the internet a variety of services emerge and service providers serve services such as using users´ private information. Service providers require many types of information related users even including sensitive private information to serve a service with high quality, but users are reluctant to disclose their private information. Because if the private information is leaked it will lead to an invasion of privacy of users and may arise some problems about users´ life. Nevertheless, service providers want to collect the users´ information because of increasing their efficiency of services. As a result, it brings about a conflict of the loss and gain between users and service providers. Anonymity is one of the solutions. Anonymity can get rid of linkability between transaction and users´ private information. Therefore, users can provide their private information without concerns about leaking it and service providers can collect many types of information and serve services with high quality. However, anonymity may be abused, and used to undermine the protection goal of accountability. Namely, a person who is assured anonymity may serve information which is not related him/her. It may be reduced the quality of services. Revocation of anonymity can make up for weak point of anonymity. But when anonymity is revoked legal dispute may be arisen and there is a cost of time or money. In this paper, we propose a scheme for accountable privacy using secret sharing and some cryptographic methods. The scheme we propose reduces a cost of revocation of anonymity because there is maybe no legal dispute and keeps anonymity more secure against collusion between service provider and revocation authority.