Policy-based Signatures (PBS), which were introduced by Bellare and Fuchsbauer, enable signers to sign messages that conform to some policy, yet privacy of the policy is maintained. Bellare et al. defined the policy in any NP language. In PBS schemes for NP language, one should have a valid witness for the policy checking and signing algorithms. In this work, we consider the case of PBS for P l...

a wonder chemical and now a symbol of ecological doom (BBC). 15 July. The First Signs of Washoe (repeat). Have the chipanzees breached one of the traditional bastions of man's uniqueness, his ability to use language? (WGBH). 22 July. Take the World from Another Point of View. NOVA visits two very different scientists: Richard Feynman, a theoretical physicist and Nobel Laureate; and Jonathan Kin...

The extensible access control markup language (XACML) is the standard access control policy specification language of the World Wide Web. XACML does not provide exclusive accesses to globally resources. We do so by enhancing the policy execution framework with locks.