Manoj Sastry, Ram Krishnan and Ravi Sandhu, A New Modeling Paradigm for Dynamic Authorization in Multi-domain Systems, MMM-ACNS 2007. Full version. Google Scholar Search Shouhuai Xu and Ravi Sandhu, A Scalable and Secure Cryptographic Service, IFIP11.3 2007. Google Scholar Search Baoxian Zhao, Ravi Sandhu, Xinwen Zhang and Xiaolin Qin, Towards a Times-Based Usage Control Model, IFIP11.3 2007. Presentation Google Scholar Search Ezedin Barka and Ravi Sandhu, Framework for Agent-Based Role Delegation, ICC 2007. Google Scholar Search Min Xu, Xuxian Jiang, Ravi Sandhu and Xinwen Zhang, Towards a VMM-based Usage Control Framework for OS Kernel Integrity Protection, SACMAT 2007. Presentation Google Scholar Search Ram Krishnan, Ravi Sandhu and Kumar Ranganathan, PEI Models towards Scalable, Usable and High-Assurance Information Sharing, SACMAT 2007. Full version. Presentation Google Scholar Search Xinwen Zhang, Michael Covington, Songqing Chen and Ravi Sandhu, SecureBus: Towards Application-Transparent Trusted Computing with Mandatory Access Control, AsiaCCS 2007. Presentation Google Scholar Search Xinwen Zhang, Francesco Parisi-Presicce, and Ravi Sandhu, Towards Remote Policy Enforcement for Runtime Protection of Mobile Code Using Trusted Computing, IWSEC 2006. Presentation Google Scholar Search Xinwen Zhang, Masayuki Nakae, Michael Covington and Ravi Sandhu, A Usage-based Authorization Framework for Collaborative Computing Systems, SACMAT 2006. Presentation Google Scholar Search Ravi Sandhu, Kumar Ranganathan and Xinwen Zhang, Secure Information Sharing Enabled by Trusted Computing and PEI Models (Invited Talk), AsiaCCS 2006. Presentation Google Scholar Search Xinwen Zhang, Ravi Sandhu, and Francesco Parisi-Presicce, Safety Analysis of Usage Control Authorization Models, AsiaCCS 2006. Presentation Google Scholar Search Masayuki Nakae, Xinwen Zhang and Ravi Sandhu, A General Design Towards Secure Ad-Hoc Collaboration, AsiaCCS, 2006. Google Scholar Search Ravi Sandhu and Xinwen Zhang, Peer-to-Peer Access Control Architecture Using Trusted Computing Technology, SACMAT 2005. Presentation Google Scholar Search Ezedin Barka and Ravi Sandhu, Role-Based Delegation Model/ Hierarchical Roles (RBDM1), ACSAC 2004. Google Scholar Search Mohammad Al-Kahtani and  Ravi Sandhu, Rule-Based RBAC with Negative Authorization, ACSAC 2004. Google Scholar Search Ravi Sandhu, A Perspective on Graphs and Access Control Models (Invited Talk), ICGT 2004. Google Scholar Search Jaehong Park, Xinwen Zhang,  and Ravi Sandhu, Attribute Mutability in Usage Control, IFIP11.3 2004. Presentation Google Scholar Search Roshan Thomas and Ravi Sandhu, Towards a Multi-dimensional Characterization of Dissemination Control, POLICY, 2004. Google Scholar Search Xinwen Zhang, Jaehong Park, Francesco Parisi-Presicce, Ravi Sandhu, A Logical Specification for Usage Control, SACMAT 2004. Google Scholar Search S. Xu, W. Nelson Jr. and R. Sandhu, Enhancing Anonymity via Market Competition, Information Assurance and Security -- IEEE ITCC 2004. Google Scholar Search Roshan Thomas and Ravi Sandhu, Models, Protocols, and Architectures for Secure Pervasive Computing: Challenges and Research Directions, IEEE PerSec'04. Google Scholar Search Ravi Sandhu and Jaehong Park, Usage Control: A Vision for Next Generation Access Control, MMM-ACNS 2003. Google Scholar Search Xinwen Zhang, Jaehong Park and Ravi Sandhu, Schema based XML Security: RBAC Approach, IFIP11.3 2003. Google Scholar Search Xinwen Zhang, Sejonh Oh and Ravi Sandhu, PBDM: A Flexible Delegation Model in RBAC, SACMAT 2003. Google Scholar Search .. Mohammad A. Al-Kahtani and Ravi Sandhu, Induced Role Hierarchies with Attribute-Based RBAC, SACMAT 2003. Google Scholar Search Shouhuai Xu and Ravi Sandhu. Two Efficient and Provably Secure Schemes for Server-Assisted Threshold Signatures, RSA-CT 2003. Google Scholar Search Ravi Sandhu, Mihir Bellare, and Ravi Ganesan, Password Enabled PKI: Virtual Smartcards vs. Virtual Soft Tokens, PKIRW 2002. Presentation Google Scholar Search Mohammad A. Al-Kahtani and Ravi Sandhu, A Model for Attribute-Based User-Role Assignment, ACSAC 2002. Google Scholar Search .. Sejong Oh, Ravi S. Sandhu, A Model for Role Administration Using Organization Structure, SACMAT 2002. Google Scholar Search .. Jaehong Park and Ravi Sandhu, Towards Usage Control Models: Beyond Traditional Access Control, SACMAT 2002. Presentation Google Scholar Search .. Jaehong Park and Ravi Sandhu, Originator Control in Usage Control, POLICY 2002. Google Scholar Search Shouhuai Xu and Ravi Sandhu, Authenticated Multicast Immune to Denial-of-Service Attack, SAC 2002. Google Scholar Search Pete Epstein and Ravi Sandhu, Engineering of Role-Permission Assignments, ACSAC 2001. Google Scholar Search Joon Park, Gail-Joon Ahn and Ravi Sandhu, Role-based Access Control on the Web Using LDAP, IFIP11.3 2001. Google Scholar Search Savith Kandala and Ravi Sandhu, Secure Role-Based Workflow Models, IFIP11.3 2001. Google Scholar Search Ravi Sandhu, Future Directions in Role-Based Access Control Models (Keynote Lecture), MMM-ACNS 2001. Google Scholar Search Ezedin Barka and Ravi Sandhu, Framework for Role-Based Delegation Models, ACSAC 2000. Google Scholar Search 100+ Jaehong Park, Ravi Sandhu and James Schifalacqua, Security Architectures for Controlled Digital Information Dissemination, ACSAC 2000. Google Scholar Search Joon S. Park and Ravi Sandhu, Binding Identities and Attributes Using Digitally Signed Certificates, ACSAC 2000. Google Scholar Search Ezedin Barka and Ravi Sandhu, A Role-Based Delegation Model and Some Extensions, NISSC 2000. Google Scholar Search .. Venkata Bhamidipat and Ravi Sandhu, Push Architectures for User-Role Assignment, NISSC 2000. Google Scholar Search Ravi Sandhu, Engineering Authority and Trust in Cyberspace: The OM-AM and RBAC Way, ACM RBAC 2000. Google Scholar Search Ravi Sandhu, David Ferraiolo and Richard Kuhn, The NIST Model for Role-Based Access Control: Towards A Unified Standard, ACM RBAC 2000. Google Scholar Search 300+ Gail-Joon Ahn, Myong Kang, Joon Park and Ravi Sandhu, Injecting RBAC to Secure a Web-Based Workflow System, ACM RBAC 2000. Google Scholar Search .. Gail-Joon Ahn and Ravi Sandhu, The RSL99 Language for Role-Based Separation of Duty Constraints, ACM RBAC 1999. Google Scholar Search .. Pete Epstein and Ravi Sandhu, Towards a UML Based Approach to Role Engineering, ACM RBAC 1999. Google Scholar Search .. Joon S. Park and Ravi Sandhu, RBAC on the Web by Smart Certificates, ACM RBAC 1999. Google Scholar Search .. Ravi Sandhu and Qamar Munawer, Simulation of the Augmented Typed Access Matrix Model (ATAM) Using Roles, INFOSECU 1999. Google Scholar Search Ravi Sandhu and Qamar Munawer, The ARBAC99 Model for Administration of Roles, ACSAC 1999. Google Scholar Search .. Joon S. Park and Ravi Sandhu, Smart Certificates: Extending X.509 for Secure Attribute Service on the Web, NISSC 1999. Google Scholar Search Joon Park, Ravi Sandhu, and SreeLatha Ghanta, RBAC on the Web by Secure Cookies, IFIP11.3 1999. Google Scholar Search Savith Kandala and Ravi Sandhu, Extending the BFA Workflow Authorization Model to Express Weighted Voting, IFIP11.3 1999. Google Scholar Search Philip Hyland and Ravi Sandhu, Concentric Supervision of Security Applications: A New Security Management Paradigm, ACSAC 1998. Google Scholar Search Ravi Sandhu and Gail-Joon Ahn, Group Hierarchies with Decentralized User Assignment in Windows NT, IASTED-CSE 1998. Google Scholar Search Ravi Sandhu and Qamar Munawer, The RRA97 Model for Role-Based Administration of Role Hierarchies, ACSAC 1998. Google Scholar Search Ravi Sandhu and Qamar Munawer, How to do Discretionary Access Control Using Roles, ACM RBAC 1998. Google Scholar Search .. Ravi Sandhu, Role Activation Hierarchies, ACM RBAC 1998. Google Scholar Search ... Ravi Sandhu and Venkata Bhamidipadi, An Oracle Implementation of the PRA97 Model for Permission-Role Assignment, ACM RBAC 1998. Google Scholar Search Ravi Sandhu and Joon S. Park, Decentralized User-Role Assignment for Web-based Intranets, ACM RBAC 1998. Google Scholar Search Philip Hyland and Ravi Sandhu, Management of Network Security Applications, NISSC 1998. Google Scholar Search Ravi Sandhu and Gail-Joon Ahn, Decentralized Group Hierarchies in UNIX: An Experiment and Lessons Learned, NISSC 1998. Google Scholar Search Chandramouli Ramaswamy and Ravi Sandhu, Role-Based Access Control Features in Commercial Database Management Systems (Winner of Best Paper Award), NISSC 1998. Google Scholar Search Tarik Himdi and Ravi Sandhu, Lattice Based Models for Controlled Sharing of Confidential Information in The Saudi Hajj System, ACSAC 1997. Google Scholar Search Ravi Sandhu, Venkata Bhamidipadi, Edward Coyne, Srinivas Ganta and Charles Youman, The ARBAC97 Model for Role-Based Administration of Roles: Preliminary Description and Outline, ACM RBAC 1997. Google Scholar Search .. Ravi Sandhu and Venkata Bhamidipadi, The URA97 Model for Role-Based User-Role Assignment, IFIP11.3 1997. Google Scholar Search Roshan Thomas and Ravi Sandhu, Task-based Authorization Controls (TBAC): A Family of Models for Active and Enterprise-oriented Authorization Management, IFIP11.3 1997. Google Scholar Search 100+ Ravi Sandhu, Role Hierarchies and Constraints for Lattice-Based Access Controls, ESORICS 1996. Google Scholar Search 100+ Ravi Sandhu, Access Control: The Neglected Frontier (Keynote Lecture), ACISP 1996. Google Scholar Search Ravi Sandhu, Issues in RBAC, ACM RBAC 1995. Google Scholar Search Ravi Sandhu, Roles Versus Groups, ACM RBAC 1995. Google Scholar Search Ravi Sandhu, Rationale for the RBAC96 Family of Access Control Models, ACM RBAC 1995. Google Scholar Search .. Fang Chen and Ravi Sandhu, Constraints for Role-Based Access Control, ACM RBAC 1995. Google Scholar Search .. Jeremy Epstein and Ravi Sandhu, NetWare 4 as an Example of Role-Based Access Control, ACM RBAC 1995. Google Scholar Search Fang Chen and Ravi Sandhu, The Semantics and Expressive Power of the MLR Data Model, OAKLAND 1995. Google Scholar Search Roshan Thomas and Ravi Sandhu, Conceptual Foundations for a Model of Task-based Authorizations, CSFW 1994. Google Scholar Search .. Ravi Sandhu, Edward Coyne, Hal Feinstein and Charles Youman, Role-Based Access Control: A Multi-Dimensional View, ACSAC 1994. Google Scholar Search .. Ravi Sandhu and Srinivas Ganta, On the Expressive Power of the Unary Transformation Model, ESORICS 1994. Roshan Thomas and Ravi Sandhu, Supporting Object-based High-assurance Write-up in Multilevel databases for the Replicted Architecture, ESORICS 1994. Google Scholar Search Ravi Sandhu and Hal Feinstein, A Three Tier Architecture for Role-Based Access Control, NCSC 1994. Google Scholar Search Paul Ammann and Ravi Sandhu, One-Representative Safety Analysis in the Non-Monotonic Transform Model, CSFW 1994. Google Scholar Search Ravi Sandhu and Srinivas Ganta, On the Minimality of Testing for Rights in Transformation Models, OAKLAND 1994. Google Scholar Search Roshan Thomas and Ravi Sandhu, Towards a Task-Based Paradigm for Flexible and Adaptable Access Control in Distributed Applications, NSP 1993. Google Scholar Search Roshan Thomas and Ravi Sandhu, Concurrency, Synchronization, and Scheduling to Support High-assurance Write-up in Multilevel Object-based Computing, OOPSLA Workshop 1993. Google Scholar Search Ravi Sandhu and Srinivas Ganta, Expressive Power of the Single-Object Typed Access Matrix Model, ACSAC 1993. Google Scholar Search Ravi Sandhu and Sushil Jajodia, Referential Integrity in Multilevel Secure Databases, NCSC 1993. Google Scholar Search Roshan Thomas and Ravi Sandhu, Discretionary Access Control in Object-Oriented Databases: Issues and Research Directions, NCSC 1993. Google Scholar Search Roshan Thomas and Ravi Sandhu, Task Based Authorization: A Paradigm for Flexible and Adaptable Access Control in Distributed Applications, NCSC 1993. Google Scholar Search Ravi Sandhu, On Five Definitions of Data Integrity, IFIP11.3 1993. Google Scholar Search Roshan Thomas and Ravi Sandhu, Towards a Unified Framework and Theory for Reasoning about Security and Correctness of Multilevel Transactions, IFIP11.3 1993. Google Scholar Search Ravi Sandhu and Srinivas Ganta, On Testing for Absence of Rights in Access Control Models, CSFW 1993. Google Scholar Search Paul Ammann and Ravi Sandhu, Implementing Transaction Control Expressions by Checking for Absence of Access Rights, ACSAC 1992. Google Scholar Search Ravi Sandhu and Sushil Jajodia, Polyinstantiation for Cover Stories, ESORICS 1992. Google Scholar Search Ravi Sandhu, A Lattice Interpretation of the Chinese Wall Policy, NCSC 1992. Google Scholar Search Ravi Sandhu and Gurpreet Suri, Implementation Considerations for the Typed Access Matrix Model in a Distributed Environment (Winner of Outstanding Paper Award), NCSC 1992. Google Scholar Search Ravi Sandhu, The Typed Access Matrix Model, OAKLAND 1992. Google Scholar Search 100+ Ravi Sandhu and Gurpreet Suri, Non-Monotonic Transformations of Access Rights, OAKLAND 1992. Google Scholar Search Roshan Thomas and Ravi Sandhu, Implementing the Message Filter Object-oriented Security Model without Trusted Subjects, IFIP11.3 1992. Google Scholar Search Paul Ammann, Richard Lipton and Ravi Sandhu, The Expressive Power of Multi-Parent Creation in Monotonic Access Control Models, CSFW 1992. Google Scholar Search John McDermott, Sushil Jajodia and Ravi Sandhu, A Single-Level Scheduler for the Replicated Architecture for Multilevel Secure Databases, ACSAC 1991. Google Scholar Search Paul Ammann, Ravi Sandhu and Gurpreet Suri, A Distributed Implementation of the Extended Schematic Protection Model, ACSAC 1991. Google Scholar Search Ravi Sandhu, Roshan Thomas and Sushil Jajodia, Supporting Timing Channel Free Computations in Multilevel Secure Object-Oriented Databases, IFIP11.3 1991. Google Scholar Search Ravi Sandhu and Sushil Jajodia, Honest Databases That Can Keep Secrets, NCSC 1991. Google Scholar Search Ravi Sandhu and Gurpreet Suri, A Distributed Implementation of the Transform Model, NCSC 1991. Google Scholar Search Ravi Sandhu, Roshan Thomas and Sushil Jajodia, A Secure Kernelized Architecture for Multilevel Object-Oriented Databases, CSFW 1991. Google Scholar Search Edgar Sibley, James Michael and Ravi Sandhu, A Case Study of Security Policy for Manual and Automated Systems, COMPASS 1991. Google Scholar Search Sushil Jajodia and Ravi Sandhu, Toward a Multilevel Secure Relational Data Model, SIGMOD 1991. Google Scholar Search 100+ Paul Ammann and Ravi Sandhu, Safety Analysis for the Extended Schematic Protection Model, OAKLAND 1991. Google Scholar Search Sushil Jajodia and Ravi Sandhu, A Novel Decomposition of Multilevel Relations into Single-Level Relations, OAKLAND 1991. Google Scholar Search Paul Ammann and Ravi Sandhu, Extending the Creation Operation in the Schematic Protection Model, ACSAC 1990. Google Scholar Search Sushil Jajodia, Ravi Sandhu and Edgar Sibley, Update Semantics for Multilevel Relations, ACSAC 1990. Google Scholar Search Ravi Sandhu and Sushil Jajodia, Integrity Mechanisms in Database Management Systems, NCSC 1990. Google Scholar Search Ravi Sandhu and Sushil Jajodia, Polyinstantiation Integrity in Multilevel Relations, OAKLAND 1990. Google Scholar Search .. Ravi Sandhu, Separation of Duties in Computerized Information Systems, IFIP11.3 1990. Google Scholar Search ... Sushil Jajodia and Ravi Sandhu, Polyinstantiation Integrity in Multilevel Relations Revisited,, IFIP11.3 1990. Google Scholar Search Ravi Sandhu, Sushil Jajodia and Teresa Lunt, A New Polyinstantiation Integrity Constraint for Multilevel Relations, CSFW 1990. Google Scholar Search Sushil Jajodia and Ravi Sandhu, A Formal Framework for Single Level Decomposition of Multilevel Relations, CSFW 1990. Google Scholar Search Ravi Sandhu, Mandatory Controls for Database Integrity, IFIP11.3 1989. Google Scholar Search Ravi Sandhu, Transformation of Access Rights, OAKLAND 1989. Google Scholar Search Ravi Sandhu, Terminology, Criteria and System Architectures for Data Integrity, IWDI 1989. Google Scholar Search Ravi Sandhu, Transaction Control Expressions for Separation of Duties, ACSAC 1988. Google Scholar Search 100+ Ravi Sandhu, On Some Cryptographic Solutions for Access Control in a Tree Hierarchy, ACM-IEEE 1987. Google Scholar Search Ravi Sandhu and Micheal Share, Some Owner-Based Schemes with Dynamic Groups in the Schematic Protection Model, OAKLAND 1986. Google Scholar Search Ravi Sandhu, Analysis of Acyclic Attenuating Systems for the SSR Protection Model, OAKLAND 1985. Google Scholar Search Ravi Sandhu, The SSR Model for Specification of Authorization Policies: A Case Study in Project Control, COMPSAC 1984. Google Scholar Search