Formal Aspects of Computing

, Volume 25, Issue 1, pp 3–35 | Cite as

Checking noninterference in Timed CSP

  • A. W. Roscoe
  • Jian Huang
Original Article


A well-established specification of noninterference in CSP is that, when high-level events are appropriately abstracted, the remaining low-level view is deterministic. This is not a workable definition in Timed CSP, where many processes cannot be refined to deterministic ones. We argue that in fact “deterministic” should be replaced by “maximally refined” in the definition above. We show how to automate the resulting timed noninterference check within the context of the recent extension of FDR to analyse a discrete version of Timed CSP, and how an extended theory of digitisation has the potential both to create more accurate specifications and to infer when processes are noninterfering in the more usual continuous-time semantics.


CSP Timed CSP Noninterference Refinement 


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  1. All91.
    Allen PG (1991) A comparison of non-interference and non-deducibility using CSP. Proc CSFW. IEEEGoogle Scholar
  2. AlDi94.
    Alur R, Dill DL (1994) A theory of timed automata. Theor Comput Sci 126(2): 183–235MathSciNetzbMATHCrossRefGoogle Scholar
  3. AHR12.
    Armstrong P, Hopcroft PJ, Roscoe AW (2012) Fairness analysis through priority. ForthcomingGoogle Scholar
  4. ALOR12.
    Armstrong PJ, Lowe G, Ouaknine J, Roscoe AW (2012) Model-checking Timed CSP. Forthcoming HOWARD (H. Barringer festschift), Easychair (pub)Google Scholar
  5. BFST02.
    Barbuti R, Francesco ND, Santone A, Tesei L (2002) A notion of non-interference for timed automata. Fundam Inform 51: 1–11zbMATHGoogle Scholar
  6. BaTe03.
    Barbuti R, Tesei L (2003) A decidable notion of timed non-interference. Fundam Inform 54: 137–150MathSciNetzbMATHGoogle Scholar
  7. FoGo94.
    Focardi R, Gorrieri R (1994) A classification of security properties for process algebras. J Comput Secur 3: 5–33Google Scholar
  8. FGM00.
    Focardi R, Gorrieri R, Martinelli F (2000) Information flow analysis in a discrete-time process algebra. CSFW-13, IEEEGoogle Scholar
  9. FGM03.
    Focardi R, Gorrieri R, Martinelli F (2003) Real-time information flow analysis. Sel Areas Commun 21: 20–34CrossRefGoogle Scholar
  10. For99.
    Forster R (1999) Noninterference properties for nondeterministic processes. Oxford University DPhil thesisGoogle Scholar
  11. FRR99.
    Forster R, Reed GM, Roscoe AW (2000) The successes and failures of behavioural models. In: Millenial perspectives in computer science. PalgraveGoogle Scholar
  12. GoMe82.
    Goguen JA, Meseguer J (1982) Security policies and security models. In: Proceedings of IEEE symposium on security and privacyGoogle Scholar
  13. GCu92.
    Graham-Cumming J (1992) The formal development of secure systems. Oxford University DPhil thesisGoogle Scholar
  14. HMP92.
    Henzinger TA, Manna Z, Pnueli A (1992) What good are digital clocks? In: Proceedings of the nineteenth international colloquium on automata, languages, and programming (ICALP 92), vol 623. Springer/LNCS, Berlin, pp 545–558Google Scholar
  15. Hua10.
    Huang J (2010) Extending non-interference properties to the timed world. Oxford University DPhil thesisGoogle Scholar
  16. HuRo06.
    Huang J, Roscoe AW (2006) Extending non-interference properties to the timed world. In: Proc ACM SACGoogle Scholar
  17. Laz99.
    Lazić RS (1999) A semantic study of data independence with applications to model checking. Oxford University DPhil thesisGoogle Scholar
  18. LoOu06.
    Lowe G, Ouaknine J (2006) On timed models and full abstraction. ENTCS 155: 497–519Google Scholar
  19. McIMo10.
    McIver AK, Morgan CC (2010) The thousand-and-one cryptographers. Reflections on the work of C.A.R. Hoare. Springer, BerlinGoogle Scholar
  20. Mor06.
    Morgan CC (2006) The shadow knows: refinement of ignorance in sequential programs. Proc MPC LNCS 4014Google Scholar
  21. Oua01.
    Ouaknine J (2001) Discrete analysis of continuous behaviour in real-time concurrent systems. Oxford University D.Phil thesisGoogle Scholar
  22. Oua02.
    Ouaknine J (2002) Digitisation and full abstraction for dense-time model checking. TACAS Springer LNCSGoogle Scholar
  23. OuWo03.
    Ouaknine J, Worrell JB (2003) Timed CSP = closed timed epsilon-automata. Nord J Comput 10: 99–133MathSciNetzbMATHGoogle Scholar
  24. Ree88.
    Reed GM (1988) A uniform mathematical theory for real-time distributed computing. Oxford University DPhil thesisGoogle Scholar
  25. ReRo88.
    Reed GM, Roscoe AW (1988) A timed model for communicating sequential processes. Theor Comput Sci 58: 249–261MathSciNetzbMATHCrossRefGoogle Scholar
  26. ReRo99.
    Reed GM, Roscoe AW (1999) The timed failures-stability model for CSP. Theor Comput Sci 211: 85–127MathSciNetzbMATHCrossRefGoogle Scholar
  27. Ros94.
    Roscoe AW (1994) Model checking CSP. In: A classical mind: essays in honour of C.A.R. Hoare. Prentice HallGoogle Scholar
  28. Ros95.
    Roscoe AW (1995) CSP and determinism in security modelling. Proceedings of IEEE symposium on security and privacyGoogle Scholar
  29. Ros97.
    Roscoe AW (1997) The theory and practice of concurrency. Prentice HallGoogle Scholar
  30. Ros06.
    Roscoe AW (2006) Confluence thanks to extensional determinism. ENTCS 162: 305–309Google Scholar
  31. Ros10.
    Roscoe AW (2010) Understanding concurrent systems. Springer, BerlinzbMATHGoogle Scholar
  32. RWW96.
    Roscoe AW, Woodcock JCP, Wulf L (1996) Non-interference through determinism. J Comput Secur 4(1): 27–53Google Scholar
  33. Rya91.
    Ryan PYA (1991) A CSP formulation of non-interference and unwinding. Cipher Winter 1991. IEEE PressGoogle Scholar
  34. Sch00.
    Schneider SA (2000) Concurrent and real-time systems: the CSP approach. Wiley, New YorkGoogle Scholar

Copyright information

© British Computer Society 2012

Authors and Affiliations

  1. 1.Department of Computer ScienceOxford UniversityOxfordUK

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