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Towards A Times-based Usage Control Model

Towards A Times-based Usage Control Model. Baoxian Zhao 1 , Ravi Sandhu 2 , Xinwen Zhang 3 , and Xiaolin Qin 4 1 George Mason University, Fairfax, VA, USA 2 Institute for Cyber-Security Research at the University of Texas, San Antonio, USA

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Towards A Times-based Usage Control Model

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  1. Towards A Times-based Usage Control Model Baoxian Zhao1, Ravi Sandhu2, Xinwen Zhang3, and Xiaolin Qin4 1George Mason University, Fairfax, VA, USA 2 Institute for Cyber-Security Research at the University of Texas, San Antonio, USA 3Samsung Information Systems America, San Jose, CA, USA 4 Nanjing University of Aeronautics and Astronautics, Nanjing, China presented by Baoxian Zhao

  2. Outline • Reviewing access control models • Traditional access control models • Temporal access control models • Construction of the TUCON model • Preliminaries of the TUCON model • Times-based authorizations • Authorization rules • The implementation of access control • Conclusion and Future work

  3. Reviewing existing access control models • Traditional access control models >Discretionary Access Control (DAC) >Mandatory Access Control (MAC) >Role-based Access Control (RBAC) • Temporal access control models > The temporal authorization models suggested by E.Bertino et al 94,96,98 • Only applied to the DAC model >Temporal Data Authorization Model (TDAM), A. Gal et al 02 • Adding transaction time and valid time >TRBAC 01, GTRBAC 05 >> Adding temporal constraints to RBAC Model

  4. Limitations of existing access control models • Primary consider authorization decisions constrained by certain time periods • Authorizations are static authorization decisions > Authorizations are made at the requested time and hardly recognize ongoing controls for times constrained access or for immediate revocation > Once an authorization decision is made, the object can be accessed without limitation during a valid period!

  5. Requirements of new access control • Usage of a digital object can not only be time-independent, like read and write • But alsotemporal and times-consuming, such as payment-based online reading, or a downloadable music file that can only be played 10 times within a valid period. • It means that authorization can be updated during ongoing usage

  6. The principle of the TUCON model • Keeping the time periods • Authorizations are still constrained by the time periods • Introducing usage times • Times are consumed, to meet the request that the usage of digital objects can be consumed and limited • Times are decreased by 1, to update authorization during a single access process • New features of the TUCON model • Authorizations can be updated during ongoing usage. • Authorizations can be consumed • Effectively prevent systems from the attacks of DoS, such as nimda and red codes.

  7. Difference From UCON • In UCON model, it uses ABC (Authorization, oBligation, Condition) core models to solve these problems • In TUCON model, we consider temporal and consumed factors as attributes of Authorizations rather than attributes of subjects or objects • Support delegation • TUCON is simple to be implemented.

  8. Preliminaries of TUCON Definition 1 (Periodic expression) [ Bertino et al. 98] A periodic expression is defined as , where , and are calendars，for ，and . Here let D present the set of all valid periods. Example: From 9:00 AM to 12:00PM during workdays Definition 2 (Times)Times are a set of natural numbers, formally defined as

  9. Times-based Authorizations • Definition 3 (Times Authorization) A times authorization is a 6-tuple （pt,s, o, priv, pn, g）, where , Example : Mary grants Bob 5 read privilege on the book of Sun (5, Bob, Sun, read, +, Mary) • Definition 4 (Non-Times Authorization) When pt= -1 in a tuple of times authorization, we call this kind of times authorization non-times authorization.

  10. Times-based Authorizations (cont) • Definition 5 (Times-based Authorization) A times-based authorization is a 3-tuple (time, period, auth) where time represents a time interval , period is a periodical expression, and auth is a 6-tuple authorization. ( ) Example : Between Jan. 12, 2001 and Dec. 24 , 2005, Tom has 6 times of privilege read on object file, but he can operate this privilege only on Tuesday each week. （[1/12/2001,12/24/2005]，Weaks+2.days,(6,Tom, file, read,+, Sam) )

  11. Authorization rules • Definition 6 (Grant Rule) A grant rule is defined as the form of: Li can be a trigger condition expression. Example 1 In an application system Business_system, if a registered user Bob pre-pays $1000, he can enjoy a certain super-value service m for 6 times during every Friday since the time 09/12/2006. Let this privilege be super. access( [09/12/2006,+∞] , Weeks+5.days, (6, Bob , m, super, +, Business_system)) prepay(Bob,1000) & register (Bob)

  12. Authorization rules (cont) • Definition 7 (Derived Rule) A derived rule is defined as the form of: Li can be access with conditional expressions • Example 2 Now Bob wants to transfer 3 times for enjoying the service m to another user Alice. deraccess( [09/12/2006,+ ∞ ] , Weeks+5.days, (3, Alice , m, super, +, Business_system))  access ( [09/12/2006,+ ∞ ] , Weeks+5.days, (6, Bob , m, super,+, Business system)) & give(3, Alice, m, super, Bob) & less(3,6) deraccess( [09/12/2006,+ ∞] , Weaks+5.days, (3, Bob , m, super, +, Business_system))  access ( [09/12/2006,+ ∞ ] , Weeks+5.days, (6, Bob , m, super,+, Business system)) & give(3, Alice, m, super, Bob) & less(3,6)

  13. Authorization rules (cont) • Definition 8 (Resolution Rule) A resolution rule is defined as the form of: Li can be access or deraccess or condition expressions specified by security policy Example 3 In example 2, if Alice has 4 times super right on service m. force_access( [09/12/2006,+ ∞ ] , Weaks+5.days, (7, Alice , m, super, +, Business_system))  access ( [09/12/2006,+ ∞ ] , Weeks+5.days, (4, Alice , m, super, +, Business system)) & deraccess ( [09/12/2006,+ ∞ ] , Weeks+5.days, (3, Alice , m, super, +, Business system))

  14. Completeness of rules • THEOREM 1 ( Completeness) The policy in TUCON can be specified by a non-empty set of TUCON rules. Proof: 1 no conflict decisions 2 specifying all possible decisions

  15. The Implementation of Access control • Grant privileges • Access objects • Revoke privileges

  16. Grant privileges • Times-based authorization >here, pt >0 and pn= + • Unlimited authorization >pt=-1 and pn = + How about Times-based authorization &Unlimited authorization?

  17. Access objects • Times-based Authorization Base (TAB) > A set of authorizations, in which there is no conflict authorizations. • Valid Access Function > A function to check every access request against the current TAB to determine whether the access is authorized.

  18. Revoke privileges • Time intervals > time intervals is expired! • Usage Times > pt=0 • Other factors > Abusing privileges > Breaking security policies

  19. Conclusion and Future Work • Wide applications, especially in times-metered systems • Viewed as a solution to some specific problems of mutable attributes in modern access control • Extend the model by considering different intervals and different periods. • Develop the administration of authorization in UCON Using temporal logic to express?

  20. Any Question? Thank you !

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