Cryptology ePrint Archive: Report 2009/253

Formally and Practically Relating the CK, CK-HMQV, and eCK Security Models for Authenticated Key Exchange

Cas J.F. Cremers

Abstract: Many recent key exchange (KE) protocols have been proven secure in the CK, CK-HMQV, or eCK security models. The exact relation between these security models, and hence between the security guarantees provided by the protocols, is unclear. First, we show that the CK, CK-HMQV, and eCK security models are formally incomparable. Second, we show that these models are also practically incomparable, by providing for each model attacks that are not considered by the other models. Our analysis enables us to find several previously unreported flaws in existing protocol security proofs. We identify the causes of these flaws and show how they can be avoided.

Category / Keywords: cryptographic protocols /

Date: received 1 Jun 2009, last revised 27 Jul 2010

Contact author: cas cremers at inf ethz ch

Available format(s): PDF | BibTeX Citation

Note: Minor improvements and bugfix related to eCK partial matching observations.

Version: 20100727:103626 (All versions of this report)

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