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Extensions of BAN

Extensions of BAN. by Heather Goldsby Michelle Pirtle. Overview. BAN Logic – Burrows, Abadi, and Needham GNY – Gong, Needham, Yahalom RV AT – Abadi and Tuttle VO – van Oorschot SVO – Syverson and van Oorschot Wenbo Mao – “Mao” Comparison Conclusion. BAN Logic – 1989.

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Extensions of BAN

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  1. Extensions of BAN by Heather Goldsby Michelle Pirtle CSE 914 - Michigan State University

  2. Overview • BAN Logic – Burrows, Abadi, and Needham • GNY – Gong, Needham, Yahalom • RV • AT – Abadi and Tuttle • VO – van Oorschot • SVO – Syverson and van Oorschot • Wenbo Mao – “Mao” • Comparison • Conclusion CSE 914 - Michigan State University

  3. BAN Logic – 1989 • Goal: Offer a formalization of the description and analysis of authentication protocols over distributed computer systems • State what is accomplished by the protocol • Allow reasoning about, and comparisons of, protocol assumptions • Draw attention to unnecessary actions that can be removed from a protocol • Highlight any encrypted messages that could be sent in clear text • Tool: SPEAR • Model analyzer for BAN Logic and GNY • Developed for security protocols CSE 914 - Michigan State University

  4. BAN (cont.) • Advantages • Introduced a simple and powerful notation • Logic postulates (ie. Nonce-verification rule) are straight forward to apply for deriving BAN beliefs • Disadvantages • Idealization step can cause analysis problems • No formal syntax or semantics • Does not account for improper encryption • A principal’s beliefs cannot be changed at later stages of the protocol • Logic limited to analyze authentication protocols • Honesty and trust in other principals is not addressed CSE 914 - Michigan State University

  5. Foundation of Each Logic Read across - States which logic(s) were used to design the new logic Read down - States which logic(s) extended from the logic Logics listed in increasing year of publication

  6. GNY - 1990 • Goal: Gain ability to analyze more protocols in a more consistent manner • Extends and reformulates BAN • Notions are expanded • New rules and constructs • Eliminate some of BAN’s universal assumptions • Tools: • SPEAR • Model analyzer for BAN Logic and GNY • Developed for security protocols • Pattern scanner used as a parser for “not-originated-here” notion CSE 914 - Michigan State University

  7. GNY (cont.) • Advantages • Multiple levels of trust can be used in reasoning • More protocols can be analyzed • Making some BAN assumptions explicit allows for generality • Disadvantages • R6 is unsound • Combining rules can result in unsound conclusions • The set of rules is incomplete • Some rules have redundant premises • E.g. I2 CSE 914 - Michigan State University

  8. RV – 1996 • Goal: Provide a logic of belief, based on BAN for use with a theory generator • Extension of BAN • Explicit interpretation • Idealization step • Fails to consider other interpretations • Hidden assumptions about safety of message • Responsibility • Account for principal’s irresponsible behavior • Tool: RVChecker • Theory Generator CSE 914 - Michigan State University

  9. RV (cont.) • Advantages • Maintains the original simplicity of BAN • Has tool support • Addresses principal responsibility and the idealization step • Disadvantages • No formal syntax or semantics • Unable to specify full range of protocols CSE 914 - Michigan State University

  10. AT – 1991 • Goal: Find a natural semantic model for BAN • Extensions: • Provides formal syntax and semantics • Simplifies existing BAN inference rules • Reformulates inference rules as axioms • Removes need for honesty CSE 914 - Michigan State University

  11. AT (cont.) • Advantages • Formal syntax and semantics • Addresses question of principal honesty • More elegant proof system owing to rules of BAN being rewritten as axioms • Disadvantages • No tool support • Assumes perfect encryption • Does not address idealization step CSE 914 - Michigan State University

  12. VO – 1993 • Goal: Extend BAN family of logics in a manner that allows authenticated key agreement protocols to be analyzed, and to better examine goals and beliefs in the protocols. • Extensions • Refine the BAN construct “shares the good crypto key” • Define new key confirmation primitive • Define new postulates for use with reasoning about “jointly established” keys CSE 914 - Michigan State University

  13. VO (cont.) • Advantages • Accomplishes analysis of a new set of protocols • Allows for a closer analysis of the goals and beliefs of the new set of protocols • Disadvantages • Time is ignored • Message ordering is not addressed CSE 914 - Michigan State University

  14. SVO – 1994 • Goal: Unification of BAN, GNY, AT, & VO • Extensions: • Include public keys • New functions • Message comprehensibility CSE 914 - Michigan State University

  15. SVO (cont.) • Advantages • Proved to be sound • Disadvantages • Not suited for tool support • SVD revamped SVO: developed to be compatible with Isabelle theorem prover CSE 914 - Michigan State University

  16. Mao – 1995 • Goal: Formalize the idealization step • Extension: • Rule-based idealization technique • Remove need for perfect encryption assumption CSE 914 - Michigan State University

  17. Mao (cont.) • Advantages • Formalization of idealization technique • Eliminates assumption of perfect cryptography • Disadvantages • No tool support • No proof of soundness for idealization rules CSE 914 - Michigan State University

  18. Comparison Table Part 1 CSE 914 - Michigan State University

  19. Comparison Table Part 2 CSE 914 - Michigan State University

  20. Conclusions • BAN gave a very good foundation to expand upon • BAN-like logics do not need to be limited to authentication protocols • No one logic can or will cover all aspects of protocol analysis • More tool support is needed CSE 914 - Michigan State University

  21. Possible Future Work • Possible extensions to our work: • Include other BAN-like logics • Gaarder Snekkenes - GS • Sigrid Gurgens – SG • Mao and Boyd • SVD – An extension of SVO • Design and develop tool support CSE 914 - Michigan State University

  22. References • Kindred, "Theory Generation for Security Protocols“. 1999. http://reports-archive.adm.cs.cmu.edu/anon/1999/CMU-CS-99-130.pdf • Mao, "An Augmentation of BAN-Like Logics“. 1995. http://www.citeseer.nj.nec.com/mao95augmentation.html • Syverson and van Oorschot, "On unifying some cryptographic protocol logics“. 1994. http://www.citeseer.nj.nec.com/syverson94unifying.html • M. Abadi and M. Tuttle, "A Semantics for a Logic of Authentication“. http://www.citeseer.nj.nec.com/article/abadi91semantics.html • Burrows, Abadi & Needham, “A Logic of Authentication”. 1989. http://citeseer.nj.nec.com/burrows90logic.html • Gong, Needham and Yahalom, "Reasoning About Belief in Cryptographic Protocols”. 1990. http://citeseer.nj.nec.com/gong90reasoning.html • van Oorschot,”Extending cryptographic logics of belief to key agreement protocols”. 1993. http://doi.acm.org/10.1145/168588.168617 CSE 914 - Michigan State University

  23. Relationships Among Logics BAN - 1989 GS - 1991 GNY - 1990 RV - 1996 AT - 1991 VO - 1993 SG - 1996? SVO - 1994 Mao - 1995 CSE 914 - Michigan State University

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