Pub Date : 2021-09-16DOI: 10.1109/CSF54842.2022.9919639
Peixuan Li, Danfeng Zhang
Noninterference offers a rigorous end-to-end guarantee for secure propagation of information. However, real-world systems almost always involve security requirements that change during program execution, making noninterference inapplicable. Prior works alleviate the limitation to some extent, but even for a veteran in information flow security, understanding the subtleties in the syntax and semantics of each policy is challenging, largely due to very different policy specification languages, and more fundamentally, semantic requirements of each policy. We take a top-down approach and present a novel information flow policy, called Dynamic Release, which allows information flow restrictions to downgrade and upgrade in arbitrary ways. Dynamic Release is formalized on a novel framework that, for the first time, allows us to compare and contrast various dynamic policies in the literature. We show that Dynamic Release generalizes declassification, erasure, delegation and revocation. Moreover, it is the only dynamic policy that is both applicable and correct on a benchmark of tests with dynamic policy.
{"title":"Towards a General-Purpose Dynamic Information Flow Policy","authors":"Peixuan Li, Danfeng Zhang","doi":"10.1109/CSF54842.2022.9919639","DOIUrl":"https://doi.org/10.1109/CSF54842.2022.9919639","url":null,"abstract":"Noninterference offers a rigorous end-to-end guarantee for secure propagation of information. However, real-world systems almost always involve security requirements that change during program execution, making noninterference inapplicable. Prior works alleviate the limitation to some extent, but even for a veteran in information flow security, understanding the subtleties in the syntax and semantics of each policy is challenging, largely due to very different policy specification languages, and more fundamentally, semantic requirements of each policy. We take a top-down approach and present a novel information flow policy, called Dynamic Release, which allows information flow restrictions to downgrade and upgrade in arbitrary ways. Dynamic Release is formalized on a novel framework that, for the first time, allows us to compare and contrast various dynamic policies in the literature. We show that Dynamic Release generalizes declassification, erasure, delegation and revocation. Moreover, it is the only dynamic policy that is both applicable and correct on a benchmark of tests with dynamic policy.","PeriodicalId":412553,"journal":{"name":"2022 IEEE 35th Computer Security Foundations Symposium (CSF)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130405388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-06DOI: 10.1109/CSF54842.2022.9919664
Felipe Boeira, Mikael Asplund
Vehicular networks will enable a range of novel applications to enhance road traffic efficiency, safety, and reduce fuel consumption. As for other cyber-physical systems, security is essential to the deployment of these applications and standardisation efforts are ongoing. In this paper, we perform a systematic security evaluation of a vehicular platooning protocol through a thorough analysis of the protocol and security standards. We tackle the complexity of the resulting model with a proof strategy based on a relation on keys. The key relation forms a partial order, which encapsulates both secrecy and authenticity dependencies. We show that our order-aware approach makes the verification feasible and proves authenticity properties along with secrecy of all keys used throughout the protocol.
{"title":"Exploiting Partial Order of Keys to Verify Security of a Vehicular Group Protocol","authors":"Felipe Boeira, Mikael Asplund","doi":"10.1109/CSF54842.2022.9919664","DOIUrl":"https://doi.org/10.1109/CSF54842.2022.9919664","url":null,"abstract":"Vehicular networks will enable a range of novel applications to enhance road traffic efficiency, safety, and reduce fuel consumption. As for other cyber-physical systems, security is essential to the deployment of these applications and standardisation efforts are ongoing. In this paper, we perform a systematic security evaluation of a vehicular platooning protocol through a thorough analysis of the protocol and security standards. We tackle the complexity of the resulting model with a proof strategy based on a relation on keys. The key relation forms a partial order, which encapsulates both secrecy and authenticity dependencies. We show that our order-aware approach makes the verification feasible and proves authenticity properties along with secrecy of all keys used throughout the protocol.","PeriodicalId":412553,"journal":{"name":"2022 IEEE 35th Computer Security Foundations Symposium (CSF)","volume":"158 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132843904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-05DOI: 10.1109/CSF54842.2022.9919666
Ross Horne, S. Mauw, S. Yurkov
To address known privacy problems with the EMV standard, EMVCo have proposed a Blinded Diffie-Hellman key establishment protocol, which is intended to be part of a future 2nd Gen EMV protocol. We point out that active attackers were not previously accounted for in the privacy requirements of this proposal protocol, and demonstrate that an active attacker can compromise unlinkability within a distance of 100cm. Here, we adopt a strong definition of unlinkability that does account for active attackers and propose an enhancement of the protocol proposed by EMVCo. We prove that our protocol does satisfy strong unlinkability, while preserving authentication.
{"title":"Unlinkability of an Improved Key Agreement Protocol for EMV 2nd Gen Payments","authors":"Ross Horne, S. Mauw, S. Yurkov","doi":"10.1109/CSF54842.2022.9919666","DOIUrl":"https://doi.org/10.1109/CSF54842.2022.9919666","url":null,"abstract":"To address known privacy problems with the EMV standard, EMVCo have proposed a Blinded Diffie-Hellman key establishment protocol, which is intended to be part of a future 2nd Gen EMV protocol. We point out that active attackers were not previously accounted for in the privacy requirements of this proposal protocol, and demonstrate that an active attacker can compromise unlinkability within a distance of 100cm. Here, we adopt a strong definition of unlinkability that does account for active attackers and propose an enhancement of the protocol proposed by EMVCo. We prove that our protocol does satisfy strong unlinkability, while preserving authentication.","PeriodicalId":412553,"journal":{"name":"2022 IEEE 35th Computer Security Foundations Symposium (CSF)","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126211776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-11-28DOI: 10.1109/CSF54842.2022.9919656
Peeter Laud, A. Pankova
Differential privacy is a privacy technique with provable guarantees which is typically achieved by introducing noise to statistics before releasing them. The level of privacy is characterized by a certain numeric parameter E > 0, where smaller E means more privacy. However, there is no common agreement on how small E should be, and the actual likelihood of data leakage for the same E may vary for different released statistics and different datasets. In this paper, we show how to relate E to the increase in the probability of attacker's success in guessing something about the private data. The attacker's goal is stated as a Boolean expression over guessing particular categorical and numerical attributes, where numeric attributes can be guessed with some precision. The paper is built upon the definition of d-privacy, which is a gencralization of E-differential privacy.
{"title":"Interpreting Epsilon of Differential Privacy in Terms of Advantage in Guessing or Approximating Sensitive Attributes","authors":"Peeter Laud, A. Pankova","doi":"10.1109/CSF54842.2022.9919656","DOIUrl":"https://doi.org/10.1109/CSF54842.2022.9919656","url":null,"abstract":"Differential privacy is a privacy technique with provable guarantees which is typically achieved by introducing noise to statistics before releasing them. The level of privacy is characterized by a certain numeric parameter E > 0, where smaller E means more privacy. However, there is no common agreement on how small E should be, and the actual likelihood of data leakage for the same E may vary for different released statistics and different datasets. In this paper, we show how to relate E to the increase in the probability of attacker's success in guessing something about the private data. The attacker's goal is stated as a Boolean expression over guessing particular categorical and numerical attributes, where numeric attributes can be guessed with some precision. The paper is built upon the definition of d-privacy, which is a gencralization of E-differential privacy.","PeriodicalId":412553,"journal":{"name":"2022 IEEE 35th Computer Security Foundations Symposium (CSF)","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127964433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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