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Security

Security. Vishal Kher 10 February 2003. Objectives. Authentication and Access Control Using Role Based Access Control (RBAC) Key Management Of keys used for access control. Request For Access. Access Control - General Picture. Minimize interaction between client – RM RBAC

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Security

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  1. Security Vishal Kher 10 February 2003

  2. Objectives • Authentication and Access Control • Using Role Based Access Control (RBAC) • Key Management • Of keys used for access control

  3. Request For Access Access Control - General Picture • Minimize interaction between client – RM • RBAC • A role is a set of transactions (operation) that a user can perform within the context of an organization • Access control decision based on the role a user plays within an organization RM Client Certificate/ Capability Req, Certificate Data OBSD

  4. General Architecture • Basic Entities • Clients • Role Manager • Performs user–role association • Regional Manager can play the part of Role Manager • Devices • Have Role-based ACL • Do not need any information about identify of the client • Two Possible schemes • Shared secret • Public key-certificates

  5. Private Communication Scheme Using Shared Secret • Role Manager and Device share KRD Device Client Role Manager Access Authenticate and assign roles T = {Roles, start time, end time, version}, K = MACKRD(T) M = {T, Oper, Nonce} & MACK(M) • Validates: • MACK(M) • Access Rights Reply, Nonce, MACK(M)

  6. Scheme Using Shared Secret • Issues • Role-based capability bound to the device and regional manager • Compound objects • KRD is shared between device and role manager • Every user will need to acquire a role-based capability per device • Need a scheme to support global role-base capability • Mobility of the object and replication will need an efficient scheme • Revocation • Currently, we are focusing on this scheme

  7. Using Public-Key Certificates • Each Role Manager and Client will have a public-key certificate • Binds public key to an identity • Role Manager issues a certificate to the client • Binds roles to the client • The device authenticates and authorizes client using the role certificate

  8. Using Public-Key Certificates VersionSerial NumberIssuerSubjectPublic-key info[…] CA Digital Signature RoleIssuerValid period[…] Role Manager’s Digital Signature Example of a Role Certificate (R-cert)

  9. Using Public-Key Certificates Clients Role Manager (RM) Device Access Authenticate Assign role Create R-cert Return R-cert Operation, R-cert, Client-Signature • Verify client signature • Verify RM Signature • Verify other fields • Retrieve role • Get access rights for this role Response

  10. Using Public-Key Certificates • Advantages • Flexibility • Certificate is not dependent on the device and the role manager • Mobility of object or device does not require generation of new certificate • Issues • Expensive • Revocation

  11. Key Management • Issues • Where and how to store the keys? • Revocation • Merging of roles • How to share a secret? • Goes hand in hand with the access control scheme

  12. Conclusion • Survey systems that use decentralized RBAC • Currently implemented by few hospitals • Propose schemes for access control and key management

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