Context-based Access Control

1. Context-based Access Control A. Corradi, R. Montanari & D. Tibaldi,“Context-Based Access Control Management in Ubiquitous Environments”,Network Computing and Applications, Third IEEE International Symposium on (NCA'04), August 30 - September 01, 2004, Boston, MA. A review by A. Escobar & Dr. Maria Petrie Department of Computer Science Florida Atlantic University March 31st , 2005

2. Context-based Access Control • Traditional RBAC not applicable. • Service providers do NOT know in advance the identities/roles of all subjects. • Users could be unknown entities. - RBAC model taken from [Fer04]

3. Context-based Access Control • Context-based AC (CBAC). • As with role, context provides a level of indirection between users and permissions.

4. Sys. Allowed View Desired View Resource Allowed View Resource Allowed View Desired View Active-Context View Active-Context View Security Framework: • Corradi’s Contribution: • Allows flexible solutions for CBAC. • Defines 3 views: • Desired View : Resources that a user is willing to access. • Allowed View : Accessible Resources depending on context-dependent AC Policies. • Active-Context View : Desired View ∩ Allowed View. • Supports Privacy of user context information. Sys. Allowed View Allowed View Desired View Active-Context View

5. Context Model • Corradi’s Contribution: • Physical Context: • Identify physical spaces. • There is only one per user. • Holds references to the protected resources. • Logical Context: • Identify logical states of users and resources. • Many per user/resource. Not UML and taken From [Cor04]

6. Context Model • Our Contribution: • UML representation of Corradi’s Context Model. in User * * Logical_Context Location_Context {User may only be in 1 Location_Context at a time}

7. Context name: type: {Physical | Logical}activation_cond.:Set of Predicates activate( ); deactivate ( ); Corradi’s Framework for Physical Context: Physical Context Our UML interpretation: Physical_Context name = “Cinema” type = Physical activation_cond=GeoCoordinate.IsEqual(Area.GetInfo) activate( ); deactivate ( );

8. Logical_Context name: “Tourist” type: Logicalactivation_cond.:MonitoringSystem.GetVisitNumber.IsLess(N) activate( ); deactivate ( ); Logical Context Corradi’s Framework for Logical Context: Our UML interpretation:

9. Resource name: description: Resource Corradi’s Framework for Resource: Our UML interpretation:

10. User * * protects Logical_Context Location_Context Resource name: description: Context name: type:activation_cond.: Context Model • Our Contribution: • UML representation of Corradi’s Context Model.

11. Security Model • Corradi’s Contribution : • Allow System Administrators and Users specify their own policies. • Introduces Metadata: • User/Device/Resource Profiles (Security logic). • Access Control Policies (Security control). • Allowing separation between security logic and security control. Not UML and taken From [Cor04]

12. User_Profile properties desired_view Profiles • User Profile • Properties • Desired View • Desired Objects. • Desired Actions to be performed on Desired Objects. • Context Conditions to perform the Desired Actions. • Device Profile : Don’t know the substructure. • Resource Profile: Don’t know the substructure.

13. User_Profile properties desired_view A User Profile

14. Property * Profile Desired_View Objects Actions Context_Cond. 1 User_Profile Device_Profile Resource_Profile Profiles • Our Contribution: • UML representation of Corradi’s Profile.

15. Property User * Profile Desired_View Objects Actions Context_Cond. * * 1 protects Logical_Context Location_Context Resource name: description: User_Profile Device_Profile Resource_Profile Context name: type:activation_cond.: Security Model • Our Contribution: • UML representation of Corradi’s Security Model. 1 * Devi ce

16. Access Control Policies • Association rules between set of permissions and set of contexts. • Simple Association ( One permission to One Context) • And, Or & Dependence Associations (One permission to many Contexts) • System Level. • Administrator defines permissions. • Protect system resources • User Level. • User defines permissions. • Protect user privacy.

17. Resource name: description: Permission name: action: kind: < s, o, t, p > target o t Corradi’s Permission: Permission Our UML interpretation:

18. Resource name: description: CBAC Policy assoc_type:{Simple|Or|And|Dependence} allowed_view() 1..* Context Permission name: action: kind: target 1 System_Policy User_policy Context-Based Access Control Policies

19. Property User * Profile protects Desired_View Objects Actions Context_Cond. * * Context name: type:activation_cond.: 1 Logical_Context Location_Context Resource name: description: User_Profile Device_Profile Resource_Profile CBAC Policy assoc_type:{Simple|Or|And|Dependence} allowed_view() 1..* Context Permission name: action: kind: target 1 System_Policy User_policy * * 1 * Device

20. MBAC Pattern MBAC pattern taken from [Fer04]

21. Right accessType Not mapped yet Device Device Profile MBAC Pattern CBAC Policy 1..* protects <<resource>> 1..* <<user>> Context Subject Object physical target * * 1 AttributeValue PropertyValue <<permission>> value value * * 1 1 <<user_profile >> <<property>> <<resource_profile >> <<property>> * * Subject Descriptor Attribute Property Object Descriptor isAuthorized For 1 1 * * <<desired_view >> <<desired_view >> Property Qualifier Attribute Qualifier * * operator operator value value MBAC pattern taken from [Fer04]

22. References • [Boo98] G. Booch, J. Rumbaugh, I. Jacobson “The Unified Modeling Language User Guide”, Addison-Wesley Pub Co; 1st edition (September 30, 1998). • [Cor04] A. Corradi, R. Montanari, D. Tibaldi, “Context-Based Access Control Management in Ubiquitous Environments”, Network Computing and Applications, Third IEEE International Symposium on (NCA'04), August 30 - September 01, 2004, Boston, MA. • [DeC03] S. DeCapitani di Vimercati, S. Paraboschi, P. Samarati “Access control: principles and solutions”, ACM Software—Practice & Experience, John Wiley & Sons,33 (5):397-421, April 2003. • [Fer04] T. Priebe, E.B.Fernandez, J.I.Mehlau, and G. Pernul, “A Pattern System for Access Control” Procs. of  the 18th. Annual IFIP WG 11.3 Working Conference on Data and Applications Security, Sitges, Spain, July 2004, 235-249. • [San96] R. Sandhu, E. Coyne, H. Feinstein, C. Youman "Role-Based Access Control models", IEEEComputer , 29(2):38-47, February 1996. • [San94] R. Sandhu, P. Samarati, “Access Control: Principles and Practice”,IEEE Communications Magazine (1994, 40-48).