Analysing PKCS#11 Key Management APIs with Unbounded Fresh Data
We extend Delaune, Kremer and Steel’s framework for analysis of PKCS#11-based APIs from bounded to unbounded fresh data. We achieve this by: formally defining the notion of an attribute policy; showing that a well-designed API should have a certain class of policy we call complete; showing that APIs with complete policies may be safely abstracted to APIs where the attributes are fixed; and proving that these static APIs can be analysed in a small bounded model such that security properties will hold for the unbounded case. We automate analysis in our framework using the SAT-based security protocol model checker SATMC. We show that a symmetric key management subset of the Eracom PKCS#11 API, used in their ProtectServer product, preserves the secrecy of sensitive keys for unbounded numbers of fresh keys and handles, i.e. pointers to keys. We also show that this API is not robust: if an encryption key is lost to the intruder, SATMC finds an attack whereby all the keys may be compromised.
KeywordsModel Checker Object State Token State Ground Term Atom Substitution
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- 4.Courant, J., Monin, J.-F.: Defending the bank with a proof assistant. In: Proceedings of the 6th International Workshop on Issues in the Theory of Security (WITS 2006), Vienna, Austria, March 2006, pp. 87–98 (2006)Google Scholar
- 7.Krhovják, J.: PKCS #11 based APIs. Talk given at the Analysis of Security APIs Workshop (ASA-1) (July 2007), http://homepages.inf.ed.ac.uk/gsteel/asa/slides/
- 8.RSA Security Inc., v2.20. PKCS #11: Cryptographic Token Interface Standard (June 2004)Google Scholar
- 9.Tsalapati, E.: Analysis of PKCS#11 using AVISPA tools. Master’s thesis, University of Edinburgh (2007)Google Scholar
- 10.Youn, P.: The analysis of cryptographic APIs using the theorem prover Otter. Master’s thesis, Massachusetts Institute of Technology (2004)Google Scholar