Iranian Society of Cryptology The ISC International Journal of Information Security 2008-2045 3 2 2012 05 19 A model for specification, composition and verification of access control policies and its application to web services 103 120 39190 10.22042/isecure.2015.3.2.4 EN Z. Derakhshandeh B. Tork Ladani Journal Article 2010 12 18 Despite significant advances in the access control domain, requirements of new computational environments like web services still raise new challenges. Lack of appropriate method for specification of access control policies (ACPs), composition, verification and analysis of them have all made the access control in the composition of web services a complicated problem. In this paper, a new independent formal model called Constrained Policy Graph (CPG) for specification of ACPs and their composition as well as verification of conflict or incompatibility among the ACPs is represented. It is shown how CPG can be used in modeling and verification of web service composition ACPs. Also the application of CPG for modeling policies in BPEL processes -as the most common composition method for web services- is illustrated. https://www.isecure-journal.com/article_39190_f4491fcc2896910ad60de6986f83b31c.pdf