Our goal is to certify absence of information leaks in multi-agent workflows, such as conference management systems like EasyChair. These workflows can be executed by any number of agents some of which may form coalitions against the system. Therefore, checking noninterference is a challenging problem. Our paper offers two main contributions: First, a technique is provided to translate noninterference (in presence of various agent capabilities and declassification conditions) into universally quantified invariants of an instrumented new workflow program. Second, general techniques are developed for checking and inferring universally quantified inductive invariants for workflow programs. In particular, a large class of workflows is identified where inductiveness of invariants is decidable, as well as a smaller, still useful class of workflows where the weakest inductive universal invariant implying the desired invariant, is effectively computable. The new algorithms are implemented and applied to certify noninterference for workflows arising from conference management systems.
{"title":"Inductive Invariants for Noninterference in Multi-agent Workflows","authors":"C. Müller, H. Seidl, E. Zalinescu","doi":"10.1109/CSF.2018.00025","DOIUrl":"https://doi.org/10.1109/CSF.2018.00025","url":null,"abstract":"Our goal is to certify absence of information leaks in multi-agent workflows, such as conference management systems like EasyChair. These workflows can be executed by any number of agents some of which may form coalitions against the system. Therefore, checking noninterference is a challenging problem. Our paper offers two main contributions: First, a technique is provided to translate noninterference (in presence of various agent capabilities and declassification conditions) into universally quantified invariants of an instrumented new workflow program. Second, general techniques are developed for checking and inferring universally quantified inductive invariants for workflow programs. In particular, a large class of workflows is identified where inductiveness of invariants is decidable, as well as a smaller, still useful class of workflows where the weakest inductive universal invariant implying the desired invariant, is effectively computable. The new algorithms are implemented and applied to certify noninterference for workflows arising from conference management systems.","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"2550 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127481654","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}
We study the runtime verification of hyperproperties, expressed in the temporal logic HyperLTL, as a means to inspect a system with respect to security polices. Runtime monitors for hyperproperties analyze trace logs that are organized by common prefixes in the form of a tree-shaped Kripke structure, or are organized both by common prefixes and by common suffixes in the form of an acyclic Kripke structure. Unlike runtime verification techniques for trace properties, where the monitor tracks the state of the specification but usually does not need to store traces, a monitor for hyperproperties repeatedly model checks the growing Kripke structure. This calls for a rigorous complexity analysis of the model checking problem over tree-shaped and acyclic Kripke structures. We show that for trees, the complexity in the size of the Kripke structure is L-complete independently of the number of quantifier alternations in the HyperLTL formula. For acyclic Kripke structures, the complexity is PSPACE-complete (in the level of the polynomial hierarchy that corresponds to the number of quantifier alternations). The combined complexity in the size of the Kripke structure and the length of the HyperLTL formula is PSPACE-complete for both trees and acyclic Kripke structures, and is as low as NC for the relevant case of trees and alternation-free HyperLTL formulas. Thus, the size and shape of both the Kripke structure and the formula have significant impact on the complexity of the model checking problem.
{"title":"The Complexity of Monitoring Hyperproperties","authors":"Borzoo Bonakdarpour, B. Finkbeiner","doi":"10.1109/CSF.2018.00019","DOIUrl":"https://doi.org/10.1109/CSF.2018.00019","url":null,"abstract":"We study the runtime verification of hyperproperties, expressed in the temporal logic HyperLTL, as a means to inspect a system with respect to security polices. Runtime monitors for hyperproperties analyze trace logs that are organized by common prefixes in the form of a tree-shaped Kripke structure, or are organized both by common prefixes and by common suffixes in the form of an acyclic Kripke structure. Unlike runtime verification techniques for trace properties, where the monitor tracks the state of the specification but usually does not need to store traces, a monitor for hyperproperties repeatedly model checks the growing Kripke structure. This calls for a rigorous complexity analysis of the model checking problem over tree-shaped and acyclic Kripke structures. We show that for trees, the complexity in the size of the Kripke structure is L-complete independently of the number of quantifier alternations in the HyperLTL formula. For acyclic Kripke structures, the complexity is PSPACE-complete (in the level of the polynomial hierarchy that corresponds to the number of quantifier alternations). The combined complexity in the size of the Kripke structure and the length of the HyperLTL formula is PSPACE-complete for both trees and acyclic Kripke structures, and is as low as NC for the relevant case of trees and alternation-free HyperLTL formulas. Thus, the size and shape of both the Kripke structure and the formula have significant impact on the complexity of the model checking problem.","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128064081","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}
We present composition theorems for security protocols, to compose a key exchange protocol and a symmetric-key protocol that uses the exchanged key. Our results rely on the computational model of cryptography and are stated in the framework of the tool CryptoVerif. They support key exchange protocols that guarantee injective or non-injective authentication. They also allow random oracles shared between the composed protocols. To our knowledge, they are the first composition theorems for key exchange stated for a computational protocol verification tool, and also the first to allow such flexibility. As a case study, we apply our composition theorems to a proof of TLS 1.3 Draft-18. This work fills a gap in a previous paper that informally claims a compositional proof of TLS 1.3, without formally justifying it.
{"title":"Composition Theorems for CryptoVerif and Application to TLS 1.3","authors":"B. Blanchet","doi":"10.1109/CSF.2018.00009","DOIUrl":"https://doi.org/10.1109/CSF.2018.00009","url":null,"abstract":"We present composition theorems for security protocols, to compose a key exchange protocol and a symmetric-key protocol that uses the exchanged key. Our results rely on the computational model of cryptography and are stated in the framework of the tool CryptoVerif. They support key exchange protocols that guarantee injective or non-injective authentication. They also allow random oracles shared between the composed protocols. To our knowledge, they are the first composition theorems for key exchange stated for a computational protocol verification tool, and also the first to allow such flexibility. As a case study, we apply our composition theorems to a proof of TLS 1.3 Draft-18. This work fills a gap in a previous paper that informally claims a compositional proof of TLS 1.3, without formally justifying it.","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127751965","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}
V. Cortier, C. Drăgan, François Dupressoir, B. Warinschi
We present a machine-checked security analysis of Belenios -- a deployed voting protocol used already in more than 200 elections. Belenios extends Helios with an explicit registration authority to obtain eligibility guarantees. We offer two main results. First, we build upon a recent framework for proving ballot privacy in EasyCrypt. Inspired by our application to Belenios, we adapt and extend the privacy security notions to account for protocols that include a registration phase. Our analysis identifies a trust assumption which is missing in the existing (pen and paper) analysis of Belenios: ballot privacy does not hold if the registrar misbehaves, even if the role of the registrar is seemingly to provide eligibility guarantees. Second, we develop a novel framework for proving strong verifiability in EasyCrypt and apply it to Belenios. In the process, we clarify several aspects of the pen-and-paper proof, such as how to deal with revote policies. Together, our results yield the first machine-checked analysis of both ballot privacy and verifiability properties for a deployed electronic voting protocol. Perhaps more importantly, we identify several issues regarding the applicability of existing definitions of privacy and verifiability to systems other than Helios. While we show how to adapt the definitions to the particular case of Belenios, our findings indicate the need for more general security notions for electronic voting protocols with registration authorities.
{"title":"Machine-Checked Proofs for Electronic Voting: Privacy and Verifiability for Belenios","authors":"V. Cortier, C. Drăgan, François Dupressoir, B. Warinschi","doi":"10.1109/CSF.2018.00029","DOIUrl":"https://doi.org/10.1109/CSF.2018.00029","url":null,"abstract":"We present a machine-checked security analysis of Belenios -- a deployed voting protocol used already in more than 200 elections. Belenios extends Helios with an explicit registration authority to obtain eligibility guarantees. We offer two main results. First, we build upon a recent framework for proving ballot privacy in EasyCrypt. Inspired by our application to Belenios, we adapt and extend the privacy security notions to account for protocols that include a registration phase. Our analysis identifies a trust assumption which is missing in the existing (pen and paper) analysis of Belenios: ballot privacy does not hold if the registrar misbehaves, even if the role of the registrar is seemingly to provide eligibility guarantees. Second, we develop a novel framework for proving strong verifiability in EasyCrypt and apply it to Belenios. In the process, we clarify several aspects of the pen-and-paper proof, such as how to deal with revote policies. Together, our results yield the first machine-checked analysis of both ballot privacy and verifiability properties for a deployed electronic voting protocol. Perhaps more importantly, we identify several issues regarding the applicability of existing definitions of privacy and verifiability to systems other than Helios. While we show how to adapt the definitions to the particular case of Belenios, our findings indicate the need for more general security notions for electronic voting protocols with registration authorities.","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"120 23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126315920","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}
Scripts on webpages could steal sensitive user data. Much work has been done, both in modeling and implementation, to enforce information flow control (IFC) of webpages to mitigate such attacks. It is common to model scripts running in an IFC mechanism as a reactive program. However, this model does not account for dynamic script behavior such as user action simulation, new DOM element generation, or new event handler registration, which could leak information. In this paper, we investigate how to secure sensitive user information, while maintaining the flexibility of declassification, even in the presence of active attackers---those who can perform the aforementioned actions. Our approach extends prior work on secure-multi-execution with stateful declassification by treating script-generated content specially to ensure that declassification policies cannot be manipulated by them. We use a knowledge-based progress-insensitive definition of security and prove that our enforcement mechanism is sound. We further prove that our enforcement mechanism is precise and has robust declassification (i.e. active attackers cannot learn more than their passive counterpart).
{"title":"Knowledge-Based Security of Dynamic Secrets for Reactive Programs","authors":"McKenna McCall, Hengrun Zhang, Limin Jia","doi":"10.1109/CSF.2018.00020","DOIUrl":"https://doi.org/10.1109/CSF.2018.00020","url":null,"abstract":"Scripts on webpages could steal sensitive user data. Much work has been done, both in modeling and implementation, to enforce information flow control (IFC) of webpages to mitigate such attacks. It is common to model scripts running in an IFC mechanism as a reactive program. However, this model does not account for dynamic script behavior such as user action simulation, new DOM element generation, or new event handler registration, which could leak information. In this paper, we investigate how to secure sensitive user information, while maintaining the flexibility of declassification, even in the presence of active attackers---those who can perform the aforementioned actions. Our approach extends prior work on secure-multi-execution with stateful declassification by treating script-generated content specially to ensure that declassification policies cannot be manipulated by them. We use a knowledge-based progress-insensitive definition of security and prove that our enforcement mechanism is sound. We further prove that our enforcement mechanism is precise and has robust declassification (i.e. active attackers cannot learn more than their passive counterpart).","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130454601","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}
Everett Hildenbrandt, M. Saxena, Nishant Rodrigues, Xiaoran Zhu, Philip Daian, Dwight Guth, Brandon M. Moore, D. Park, Yi Zhang, Andrei Stefanescu, Grigore Roşu
A developing field of interest for the distributed systems and applied cryptography communities is that of smart contracts: self-executing financial instruments that synchronize their state, often through a blockchain. One such smart contract system that has seen widespread practical adoption is Ethereum, which has grown to a market capacity of 100 billion USD and clears an excess of 500,000 daily transactions. Unfortunately, the rise of these technologies has been marred by a series of costly bugs and exploits. Increasingly, the Ethereum community has turned to formal methods and rigorous program analysis tools. This trend holds great promise due to the relative simplicity of smart contracts and bounded-time deterministic execution inherent to the Ethereum Virtual Machine (EVM). Here we present KEVM, an executable formal specification of the EVM's bytecode stack-based language built with the K Framework, designed to serve as a solid foundation for further formal analyses. We empirically evaluate the correctness and performance of KEVM using the official Ethereum test suite. To demonstrate the usability, several extensions of the semantics are presented. and two different-language implementations of the ERC20 Standard Token are verified against the ERC20 specification. These results are encouraging for the executable semantics approach to language prototyping and specification.
{"title":"KEVM: A Complete Formal Semantics of the Ethereum Virtual Machine","authors":"Everett Hildenbrandt, M. Saxena, Nishant Rodrigues, Xiaoran Zhu, Philip Daian, Dwight Guth, Brandon M. Moore, D. Park, Yi Zhang, Andrei Stefanescu, Grigore Roşu","doi":"10.1109/CSF.2018.00022","DOIUrl":"https://doi.org/10.1109/CSF.2018.00022","url":null,"abstract":"A developing field of interest for the distributed systems and applied cryptography communities is that of smart contracts: self-executing financial instruments that synchronize their state, often through a blockchain. One such smart contract system that has seen widespread practical adoption is Ethereum, which has grown to a market capacity of 100 billion USD and clears an excess of 500,000 daily transactions. Unfortunately, the rise of these technologies has been marred by a series of costly bugs and exploits. Increasingly, the Ethereum community has turned to formal methods and rigorous program analysis tools. This trend holds great promise due to the relative simplicity of smart contracts and bounded-time deterministic execution inherent to the Ethereum Virtual Machine (EVM). Here we present KEVM, an executable formal specification of the EVM's bytecode stack-based language built with the K Framework, designed to serve as a solid foundation for further formal analyses. We empirically evaluate the correctness and performance of KEVM using the official Ethereum test suite. To demonstrate the usability, several extensions of the semantics are presented. and two different-language implementations of the ERC20 Standard Token are verified against the ERC20 specification. These results are encouraging for the executable semantics approach to language prototyping and specification.","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121966593","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}
J. Almeida, M. Barbosa, G. Barthe, Hugo Pacheco, Vitor Pereira, Bernardo Portela
We give a language-based security treatment of domain-specific languages and compilers for secure multi-party computation, a cryptographic paradigm that enables collaborative computation over encrypted data. Computations are specified in a core imperative language, as if they were intended to be executed by a trusted-third party, and formally verified against an information-flow policy modelling (an upper bound to) their leakage. This allows non-experts to assess the impact of performance-driven authorized disclosure of intermediate values. Specifications are then compiled to multi-party protocols. We formalize protocol security using (distributed) probabilistic information-flow and prove security-preserving compilation: protocols only leak what is allowed by the source policy. The proof exploits a natural but previously missing correspondence between simulation-based cryptographic proofs and (composable) probabilistic non-interference. Finally, we extend our framework to justify leakage cancelling, a domain-specific optimization that allows to first write an efficient specification that fails to meet the allowed leakage upper-bound, and then apply a probabilistic pre-processing that brings leakage to the acceptable range.
{"title":"Enforcing Ideal-World Leakage Bounds in Real-World Secret Sharing MPC Frameworks","authors":"J. Almeida, M. Barbosa, G. Barthe, Hugo Pacheco, Vitor Pereira, Bernardo Portela","doi":"10.1109/CSF.2018.00017","DOIUrl":"https://doi.org/10.1109/CSF.2018.00017","url":null,"abstract":"We give a language-based security treatment of domain-specific languages and compilers for secure multi-party computation, a cryptographic paradigm that enables collaborative computation over encrypted data. Computations are specified in a core imperative language, as if they were intended to be executed by a trusted-third party, and formally verified against an information-flow policy modelling (an upper bound to) their leakage. This allows non-experts to assess the impact of performance-driven authorized disclosure of intermediate values. Specifications are then compiled to multi-party protocols. We formalize protocol security using (distributed) probabilistic information-flow and prove security-preserving compilation: protocols only leak what is allowed by the source policy. The proof exploits a natural but previously missing correspondence between simulation-based cryptographic proofs and (composable) probabilistic non-interference. Finally, we extend our framework to justify leakage cancelling, a domain-specific optimization that allows to first write an efficient specification that fails to meet the allowed leakage upper-bound, and then apply a probabilistic pre-processing that brings leakage to the acceptable range.","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121430657","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}
There are several typing results that, for certain classes of protocols, show it is without loss of attacks to restrict the intruder to sending only well-typed messages. So far, all these typing results hold only for relatively simple protocols that do not keep a state beyond single sessions, excluding stateful protocols that, e.g., maintain long-term databases. Recently, several verification tools for stateful protocols have been proposed, e.g., Set-pi, AIF-omega, and SAPIC/Tamarin, but for none of these a typing result has been established. The main contribution of this paper is a typing result, for a large class of stateful protocols, based on a symbolic protocol model. We illustrate how to connect several formalisms for stateful protocols to this symbolic model. Finally, we discuss how the conditions of our typing result apply to existing protocols, or can be achieved by minor modifications.
{"title":"A Typing Result for Stateful Protocols","authors":"A. V. Hess, S. Mödersheim","doi":"10.1109/CSF.2018.00034","DOIUrl":"https://doi.org/10.1109/CSF.2018.00034","url":null,"abstract":"There are several typing results that, for certain classes of protocols, show it is without loss of attacks to restrict the intruder to sending only well-typed messages. So far, all these typing results hold only for relatively simple protocols that do not keep a state beyond single sessions, excluding stateful protocols that, e.g., maintain long-term databases. Recently, several verification tools for stateful protocols have been proposed, e.g., Set-pi, AIF-omega, and SAPIC/Tamarin, but for none of these a typing result has been established. The main contribution of this paper is a typing result, for a large class of stateful protocols, based on a symbolic protocol model. We illustrate how to connect several formalisms for stateful protocols to this symbolic model. Finally, we discuss how the conditions of our typing result apply to existing protocols, or can be achieved by minor modifications.","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132503106","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}
Cryptographic channels aim to enable authenticated and confidential communication over the Internet. The general understanding seems to be that providing security in the sense of authenticated encryption for every (unidirectional) point-to-point link suffices to achieve this goal. As recently shown (in FSE17/ToSC17), however, the security properties of the unidirectional links do not extend, in general, to the bidirectional channel as a whole. Intuitively, the reason for this is that the increased interaction in bidirectional communication can be exploited by an adversary. The same applies, a fortiori, in a multi-party setting where several users operate concurrently and the communication develops in more directions. In the cryptographic literature, however, the targeted goals for group communication in terms of channel security are still unexplored. Applying the methodology of provable security, we fill this gap by defining exact (game-based) authenticity and confidentiality goals for broadcast communication, and showing how to achieve them. Importantly, our security notions also account for the causal dependencies between exchanged messages, thus naturally extending the bidirectional case where causal relationships are automatically captured by preserving the sending order. On the constructive side we propose a modular and yet efficient protocol that, assuming only point-to-point links between users, leverages (non-cryptographic) broadcast and standard cryptographic primitives to a full-fledged broadcast channel that provably meets the security notions we put forth.
{"title":"A Cryptographic Look at Multi-party Channels","authors":"P. Eugster, G. Marson, Bertram Poettering","doi":"10.1109/CSF.2018.00010","DOIUrl":"https://doi.org/10.1109/CSF.2018.00010","url":null,"abstract":"Cryptographic channels aim to enable authenticated and confidential communication over the Internet. The general understanding seems to be that providing security in the sense of authenticated encryption for every (unidirectional) point-to-point link suffices to achieve this goal. As recently shown (in FSE17/ToSC17), however, the security properties of the unidirectional links do not extend, in general, to the bidirectional channel as a whole. Intuitively, the reason for this is that the increased interaction in bidirectional communication can be exploited by an adversary. The same applies, a fortiori, in a multi-party setting where several users operate concurrently and the communication develops in more directions. In the cryptographic literature, however, the targeted goals for group communication in terms of channel security are still unexplored. Applying the methodology of provable security, we fill this gap by defining exact (game-based) authenticity and confidentiality goals for broadcast communication, and showing how to achieve them. Importantly, our security notions also account for the causal dependencies between exchanged messages, thus naturally extending the bidirectional case where causal relationships are automatically captured by preserving the sending order. On the constructive side we propose a modular and yet efficient protocol that, assuming only point-to-point links between users, leverages (non-cryptographic) broadcast and standard cryptographic primitives to a full-fledged broadcast channel that provably meets the security notions we put forth.","PeriodicalId":417032,"journal":{"name":"2018 IEEE 31st Computer Security Foundations Symposium (CSF)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123151809","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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