A THREE TIER ARCHITECTURE FORROLE-BASED ACCESS CONTROL
Ravi Sandhu and Hal Feinstein
Seta CorporationMcLean, VA
Ongoing NIST-funded projectOther Project Members at Seta:
Ed Coyne, Charles Youman
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RBAC
• An alternative to classical MAC and DAC
• Substantial history and tradition
• Often used to separate administrative functions
• Operator
• Auditor
• Security Officer
• User
• Extend this concept into application domain
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INTERACTION OF RBAC, MAC AND DAC
RBAC
MAC DAC
permitted accesses
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POLICY VERSUS MECHANISM
• Roles are a policy concept
• Several mechanisms can be used to implement roles
• Roles
• Groups
• Compartments
• Some mechanisms are better suited than others
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RBAC
ROLE
USER-ROLEASSIGNMENT
PRIVILEGE-ROLEASSIGNMENT
USERS PRIVILEGES
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USERS
• Users are human beings
• Each individual should be known as exactly one user
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PRIVILEGES
• Primitive privileges
• read, write, append, execute
• Abstract privileges
• credit, debit, inquiry
• Generic privileges
• auditor
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RBAC
ROLE
USER-ROLEASSIGNMENT
PRIVILEGE-ROLEASSIGNMENT
USERS PRIVILEGES
ROLEHIERARCHIES
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HIERARCHICAL ROLES
Health-Care Provider
Physician
Primary-CarePhysician
SpecialistPhysician
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HIERARCHICAL ROLES
Engineer
HardwareEngineer
SoftwareEngineer
SupervisingEngineer
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RBAC
ROLEUSERS PRIVILEGES
ROLEHIERARCHIES
CONSTRAINTS
USER-ROLEASSIGNMENT
PRIVILEGE-ROLEASSIGNMENT
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CONSTRAINTS
• Mutually Exclusive Roles
• Static Exclusion: The same individual can never hold both roles
• Dynamic Exclusion: The same individual can never hold both roles in the same context
• Prerequisite Roles
• A user must belong to one or more prerequisite roles in order to qualify for possible membership in some other role
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SCALE
• Hundreds of roles
• User-role assignment will change frequently
• Privilege-role assignment will change frequently
• Role hierarchy will change occasionally
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RBAC SUMMARY
• RBAC is a sophisticated and multi-dimensional concept
• Different products will support variations of RBAC (even if standards emerge)
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ANSI/SPARC DATABASE ARCHITECTURE
CommunityView
ImplementationView
ExternalView
ExternalView
ExternalView
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RBAC ARCHITECTURE
CommunityView
ImplementationView
ExternalView
ExternalView
ExternalView
ImplementationView
ImplementationView
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TOP TWO TIERS
CommunityView
ExternalView
ExternalView
ELIMINATION
REFINEMENT
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EXAMPLE
REFINEMENT
ELIMINATION
ROLE HIERARCHY
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REFINEMENT
ImplementationView
ImplementationView
BOTTOM TWO TIERS
CommunityView
ELIMINATION
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IMPLICITMECHANISM
ImplementationView
ImplementationView
BOTTOM TWO TIERS
CommunityView
EXPLICITMECHANISM
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IMPLICIT USER ASSIGNMENT
USER ROLEHIERARCHY
implicit assignments
explicit assignment
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EXPLICIT USER ASSIGNMENT
USER NO ROLEHIERARCHY
explicit assignments
explicit assignment
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CONCLUSION
• Further work is ongoing on
• RBAC model
• RBAC architecture
• Preliminary results are promising
