Privacy-preserving Analog of IP address Banning for users of Anonymous Communications Networks

In this paper the Nymble system add a layer of accountability to any publicly known anonymizing network is proposed. Servers can blacklist misbehaving users while maintaining their privacy, and this system shows that how these properties can be attained in a way that is practical, efficient, and sensitive to the needs of both users and services. This work will increase the mainstream acceptance of anonymizing networks such as Tor, which has, thus far, been completely blocked by several services because of users who abuse their anonymity. In future the NYMBLE system can be extended to support Subnet-based blocking. If a user can obtain multiple addresses, then nymble-based and regular  IP-address  blocking not supported. In such a situation subnet-based blocking is used. Other resources include email addresses, client puzzles and e-cash, can be used, which could provide more privacy. The system can also enhanced by supporting for  varying time periods.