We propose a language for formal specification of service-oriented architectures. The language supports the integrated specification of communication level events, policy level decisions, and the interaction between the two. We show that the reach ability problem is decidable for a fragment of service-oriented architectures. The decidable fragment is well suited for specifying, and reasoning about, security-sensitive architectures. In the decidable fragment, the attacker controls the communication media. The policies of services are centered around the trust application and trust delegation rules, and can also express RBAC systems with role hierarchy. The fragment is of immediate practical relevance: We report on the specification and verification of two security-sensitive architectures, stemming from the e-government and e-health domains.
{"title":"Integrated Specification and Verification of Security Protocols and Policies","authors":"Simone Frau, M. Dashti","doi":"10.1109/CSF.2011.9","DOIUrl":"https://doi.org/10.1109/CSF.2011.9","url":null,"abstract":"We propose a language for formal specification of service-oriented architectures. The language supports the integrated specification of communication level events, policy level decisions, and the interaction between the two. We show that the reach ability problem is decidable for a fragment of service-oriented architectures. The decidable fragment is well suited for specifying, and reasoning about, security-sensitive architectures. In the decidable fragment, the attacker controls the communication media. The policies of services are centered around the trust application and trust delegation rules, and can also express RBAC systems with role hierarchy. The fragment is of immediate practical relevance: We report on the specification and verification of two security-sensitive architectures, stemming from the e-government and e-health domains.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117038092","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}
In this paper, we investigate the computational complexity of quantitative information flow (QIF) problems. Information-theoretic quantitative relaxations of noninterference (based on Shannon entropy)have been introduced to enable more fine-grained reasoning about programs in situations where limited information flow is acceptable. The QIF bounding problem asks whether the information flow in a given program is bounded by a constant $d$. Our first result is that the QIF bounding problem is PSPACE-complete. The QIF memoryless synthesis problem asks whether it is possible to resolve nondeterministic choices in a given partial program in such a way that in the resulting deterministic program, the quantitative information flow is bounded by a given constant $d$. Our second result is that the QIF memoryless synthesis problem is also EXPTIME-complete. The QIF memoryless synthesis problem generalizes to QIF general synthesis problem which does not impose the memoryless requirement (that is, by allowing the synthesized program to have more variables then the original partial program). Our third result is that the QIF general synthesis problem is EXPTIME-hard.
{"title":"The Complexity of Quantitative Information Flow Problems","authors":"Pavol Cerný, K. Chatterjee, T. Henzinger","doi":"10.1109/CSF.2011.21","DOIUrl":"https://doi.org/10.1109/CSF.2011.21","url":null,"abstract":"In this paper, we investigate the computational complexity of quantitative information flow (QIF) problems. Information-theoretic quantitative relaxations of noninterference (based on Shannon entropy)have been introduced to enable more fine-grained reasoning about programs in situations where limited information flow is acceptable. The QIF bounding problem asks whether the information flow in a given program is bounded by a constant $d$. Our first result is that the QIF bounding problem is PSPACE-complete. The QIF memoryless synthesis problem asks whether it is possible to resolve nondeterministic choices in a given partial program in such a way that in the resulting deterministic program, the quantitative information flow is bounded by a given constant $d$. Our second result is that the QIF memoryless synthesis problem is also EXPTIME-complete. The QIF memoryless synthesis problem generalizes to QIF general synthesis problem which does not impose the memoryless requirement (that is, by allowing the synthesized program to have more variables then the original partial program). Our third result is that the QIF general synthesis problem is EXPTIME-hard.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127379585","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 a statistical test for detecting information leaks in systems with continuous outputs. We use continuous mutual information to detect the information leakage from trial runs of a probabilistic system. It has been shown that there is no universal rate of convergence for sampled mutual information, however when the leakage is zero, and under some reasonable conditions, we establish a rate for the sampled estimate, and show that it can converge to zero very quickly. We use this result to develop a statistical test for information leakage, and we use our new test to analyse a number of possible fixes for a time-based information leak in e-passports. We compare our new test with existing statistical methods, and we find that our test outperforms these other tests in almost all cases, and in one case in particular, ours is the only statistical test that can detect an information leak.
{"title":"A Statistical Test for Information Leaks Using Continuous Mutual Information","authors":"Tom Chothia, Apratim Guha","doi":"10.1109/CSF.2011.19","DOIUrl":"https://doi.org/10.1109/CSF.2011.19","url":null,"abstract":"We present a statistical test for detecting information leaks in systems with continuous outputs. We use continuous mutual information to detect the information leakage from trial runs of a probabilistic system. It has been shown that there is no universal rate of convergence for sampled mutual information, however when the leakage is zero, and under some reasonable conditions, we establish a rate for the sampled estimate, and show that it can converge to zero very quickly. We use this result to develop a statistical test for information leakage, and we use our new test to analyse a number of possible fixes for a time-based information leak in e-passports. We compare our new test with existing statistical methods, and we find that our test outperforms these other tests in almost all cases, and in one case in particular, ours is the only statistical test that can detect an information leak.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115242460","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}
Jeremiah Blocki, Nicolas Christin, Anupam Datta, Arunesh Sinha
Audit mechanisms are essential for privacy protection in permissive access control regimes, such as in hospitals where denying legitimate access requests can adversely affect patient care. Recognizing this need, we develop the first principled learning-theoretic foundation for audits. Our first contribution is a game-theoretic model that captures the interaction between the defender (e.g., hospital auditors) and the adversary (e.g., hospital employees). The model takes pragmatic considerations into account, in particular, the periodic nature of audits, a budget that constrains the number of actions that the defender can inspect, and a loss function that captures the economic impact of detected and missed violations on the organization. We assume that the adversary is worst-case as is standard in other areas of computer security. We also formulate a desirable property of the audit mechanism in this model based on the concept of regret in learning theory. Our second contribution is an efficient audit mechanism that provably minimizes regret for the defender. This mechanism learns from experience to guide the defender's auditing efforts. The regret bound is significantly better than prior results in the learning literature. The stronger bound is important from a practical standpoint because it implies that the recommendations from the mechanism will converge faster to the best fixed auditing strategy for the defender.
{"title":"Regret Minimizing Audits: A Learning-Theoretic Basis for Privacy Protection","authors":"Jeremiah Blocki, Nicolas Christin, Anupam Datta, Arunesh Sinha","doi":"10.1109/CSF.2011.28","DOIUrl":"https://doi.org/10.1109/CSF.2011.28","url":null,"abstract":"Audit mechanisms are essential for privacy protection in permissive access control regimes, such as in hospitals where denying legitimate access requests can adversely affect patient care. Recognizing this need, we develop the first principled learning-theoretic foundation for audits. Our first contribution is a game-theoretic model that captures the interaction between the defender (e.g., hospital auditors) and the adversary (e.g., hospital employees). The model takes pragmatic considerations into account, in particular, the periodic nature of audits, a budget that constrains the number of actions that the defender can inspect, and a loss function that captures the economic impact of detected and missed violations on the organization. We assume that the adversary is worst-case as is standard in other areas of computer security. We also formulate a desirable property of the audit mechanism in this model based on the concept of regret in learning theory. Our second contribution is an efficient audit mechanism that provably minimizes regret for the defender. This mechanism learns from experience to guide the defender's auditing efforts. The regret bound is significantly better than prior results in the learning literature. The stronger bound is important from a practical standpoint because it implies that the recommendations from the mechanism will converge faster to the best fixed auditing strategy for the defender.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"38 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115637057","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}
Hybrid information-flow monitors use a combination of static analysis and dynamic mechanisms to provide precise strong information security guarantees. However, unlike purely static mechanisms for information security, hybrid information-flow monitors incur run-time overhead. We show how static analyses can be used to make hybrid information-flow monitors more efficient, in two ways. First, a simple static analysis can determine when it is sound for a monitor to stop tracking the security level of certain variables. This potentially reduces run-time overhead of the monitor, particularly in applications where sensitive (i.e., confidential or untrusted) data is infrequently introduced to the system. Second, we derive sufficient conditions for soundly incorporating a wide range of memory abstractions into information-flow monitors. This allows the selection of a memory abstraction that gives an appropriate tradeoff between efficiency and precision. It also facilitates the development of innovative and sound memory abstractions that use run-time security information maintained by the monitor. We present and prove our results by extending the information-flow monitor of Russo and Sabelfeld (2010). These results bring us closer to efficient, sound, and precise enforcement of information security.
{"title":"Static Analysis for Efficient Hybrid Information-Flow Control","authors":"Scott Moore, Stephen Chong","doi":"10.1109/CSF.2011.17","DOIUrl":"https://doi.org/10.1109/CSF.2011.17","url":null,"abstract":"Hybrid information-flow monitors use a combination of static analysis and dynamic mechanisms to provide precise strong information security guarantees. However, unlike purely static mechanisms for information security, hybrid information-flow monitors incur run-time overhead. We show how static analyses can be used to make hybrid information-flow monitors more efficient, in two ways. First, a simple static analysis can determine when it is sound for a monitor to stop tracking the security level of certain variables. This potentially reduces run-time overhead of the monitor, particularly in applications where sensitive (i.e., confidential or untrusted) data is infrequently introduced to the system. Second, we derive sufficient conditions for soundly incorporating a wide range of memory abstractions into information-flow monitors. This allows the selection of a memory abstraction that gives an appropriate tradeoff between efficiency and precision. It also facilitates the development of innovative and sound memory abstractions that use run-time security information maintained by the monitor. We present and prove our results by extending the information-flow monitor of Russo and Sabelfeld (2010). These results bring us closer to efficient, sound, and precise enforcement of information security.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127938117","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 defined a new notion of computational indistinguishability: termination-insensitive computational indistinguishability (tic-indistinguishability). Tic-indistinguishability models indistinguishability with respect to distinguishers that cannot distinguish between termination and non-termination. We sketch how the new notion allows to get computational soundness results of symbolic models for equivalence-based security properties(such as anonymity) for processes that contain loops, solving an open problem.
{"title":"Termination-Insensitive Computational Indistinguishability (and Applications to Computational Soundness)","authors":"Dominique Unruh","doi":"10.1109/CSF.2011.24","DOIUrl":"https://doi.org/10.1109/CSF.2011.24","url":null,"abstract":"We defined a new notion of computational indistinguishability: termination-insensitive computational indistinguishability (tic-indistinguishability). Tic-indistinguishability models indistinguishability with respect to distinguishers that cannot distinguish between termination and non-termination. We sketch how the new notion allows to get computational soundness results of symbolic models for equivalence-based security properties(such as anonymity) for processes that contain loops, solving an open problem.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124016889","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 a Horn-clause-based framework for analysing security protocols that use emph{platform configuration registers} (PCRs), which are registers for maintaining state inside the Trusted Platform Module (TPM). In our model, the PCR state space is unbounded, and our experience shows that a na"i ve analysis using ProVerif or SPASS does not terminate. To address this, we extract a set of instances of the Horn clauses of our model, for which ProVerif does terminate on our examples. We prove the soundness of this extraction process: no attacks are lost, that is, any query derivable in the more general set of clauses is also derivable from the extracted instances. The effectiveness of our framework is demonstrated in two case studies: a simplified version of Microsoft Bit locker, and a digital envelope protocol that allows a user to choose whether to perform a decryption, or to verifiably renounce the ability to perform the decryption.
我们提出了一个基于horn条款的框架，用于分析使用emph{平台配置寄存器}(pcr)的安全协议，这些寄存器用于维护可信平台模块(TPM)内的状态。在我们的模型中，PCR状态空间是无界的，我们的经验表明，使用ProVerif或SPASS进行na ' i ve分析不会终止。为了解决这个问题，我们提取了模型中Horn子句的一组实例，ProVerif会在我们的示例中终止这些实例。我们证明了这种提取过程的合理性:没有攻击损失，即在更一般的子句集中的任何查询可派生也可以从提取的实例中派生。我们的框架的有效性在两个案例研究中得到了证明:微软比特锁的简化版本，以及数字信封协议，该协议允许用户选择是否执行解密，或者可验证地放弃执行解密的能力。
{"title":"Formal Analysis of Protocols Based on TPM State Registers","authors":"S. Delaune, S. Kremer, M. Ryan, G. Steel","doi":"10.1109/CSF.2011.12","DOIUrl":"https://doi.org/10.1109/CSF.2011.12","url":null,"abstract":"We present a Horn-clause-based framework for analysing security protocols that use emph{platform configuration registers} (PCRs), which are registers for maintaining state inside the Trusted Platform Module (TPM). In our model, the PCR state space is unbounded, and our experience shows that a na\"i ve analysis using ProVerif or SPASS does not terminate. To address this, we extract a set of instances of the Horn clauses of our model, for which ProVerif does terminate on our examples. We prove the soundness of this extraction process: no attacks are lost, that is, any query derivable in the more general set of clauses is also derivable from the extracted instances. The effectiveness of our framework is demonstrated in two case studies: a simplified version of Microsoft Bit locker, and a digital envelope protocol that allows a user to choose whether to perform a decryption, or to verifiably renounce the ability to perform the decryption.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"142 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132410634","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}
The idea of building secure systems by plugging together "secure'' components is appealing, but this requires a definition of security which, in addition to taking care of top-level security goals, is strengthened appropriately in order to be compositional. This approach has been previously studied for information-flow security of shared-variable concurrent programs, but the price for compositionality is very high: a thread must be extremely pessimistic about what an environment might do with shared resources. This pessimism leads to many intuitively secure threads being labelled as insecure. Since in practice it is only meaningful to compose threads which follow an agreed protocol for data access, we take advantage of this to develop a more liberal compositional security condition. The idea is to give the security definition access to the intended pattern of data usage, as expressed by assumption-guarantee style conditions associated with each thread. We illustrate the improved precision by developing the first flow-sensitive security type system that provably enforces a noninterference-like property for concurrent programs.
{"title":"Assumptions and Guarantees for Compositional Noninterference","authors":"H. Mantel, David Sands, Henning Sudbrock","doi":"10.1109/CSF.2011.22","DOIUrl":"https://doi.org/10.1109/CSF.2011.22","url":null,"abstract":"The idea of building secure systems by plugging together \"secure'' components is appealing, but this requires a definition of security which, in addition to taking care of top-level security goals, is strengthened appropriately in order to be compositional. This approach has been previously studied for information-flow security of shared-variable concurrent programs, but the price for compositionality is very high: a thread must be extremely pessimistic about what an environment might do with shared resources. This pessimism leads to many intuitively secure threads being labelled as insecure. Since in practice it is only meaningful to compose threads which follow an agreed protocol for data access, we take advantage of this to develop a more liberal compositional security condition. The idea is to give the security definition access to the intended pattern of data usage, as expressed by assumption-guarantee style conditions associated with each thread. We illustrate the improved precision by developing the first flow-sensitive security type system that provably enforces a noninterference-like property for concurrent programs.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128011214","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}
Provenance, or information about the origin, derivation, or history of data, is becoming an important topic especially for shared scientific or public data on the Web. It clearly has implications on security (and vice versa) yet these implications are not well-understood. A great deal of work has focused on mechanisms for recording, managing or using some kind of provenance information, but relatively little progress has been made on foundational models that define provenance and relate it to security goals such as availability, confidentiality or privacy. We argue that such foundations are essential to making meaningful progress on these problems and should be developed. In this paper, we outline a formal model of provenance, propose formalizations of security properties for provenance such as disclosure and obfuscation, and explore their implications in domains based on automata, database queries and workflow provenance graphs.
{"title":"A Formal Framework for Provenance Security","authors":"J. Cheney","doi":"10.1109/CSF.2011.26","DOIUrl":"https://doi.org/10.1109/CSF.2011.26","url":null,"abstract":"Provenance, or information about the origin, derivation, or history of data, is becoming an important topic especially for shared scientific or public data on the Web. It clearly has implications on security (and vice versa) yet these implications are not well-understood. A great deal of work has focused on mechanisms for recording, managing or using some kind of provenance information, but relatively little progress has been made on foundational models that define provenance and relate it to security goals such as availability, confidentiality or privacy. We argue that such foundations are essential to making meaningful progress on these problems and should be developed. In this paper, we outline a formal model of provenance, propose formalizations of security properties for provenance such as disclosure and obfuscation, and explore their implications in domains based on automata, database queries and workflow provenance graphs.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134491665","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}
Access control is fundamental in protecting information systems but it also poses an obstacle to achieving business objectives. We analyze this tradeoff and its avoidance in the context of systems modeled as workflows restricted by authorization constraints including those specifying Separation of Duty (SoD) and Binding of Duty (BoD).To begin with, we present a novel approach to scoping authorization constraints within workflows with loops and conditional execution. Afterwards, we consider enforcement's effects on business objectives. We identify the notion of obstruction, which generalizes deadlock within a system where access control is enforced, and we formulate the existence of an obstruction-free enforcement mechanism as a decision problem. We present lower and upper bounds for the complexity of this problem and also give an approximation algorithm that performs well when authorizations are equally distributed among users.
{"title":"Obstruction-Free Authorization Enforcement: Aligning Security with Business Objectives","authors":"D. Basin, Samuel J. Burri, G. Karjoth","doi":"10.3233/JCS-140500","DOIUrl":"https://doi.org/10.3233/JCS-140500","url":null,"abstract":"Access control is fundamental in protecting information systems but it also poses an obstacle to achieving business objectives. We analyze this tradeoff and its avoidance in the context of systems modeled as workflows restricted by authorization constraints including those specifying Separation of Duty (SoD) and Binding of Duty (BoD).To begin with, we present a novel approach to scoping authorization constraints within workflows with loops and conditional execution. Afterwards, we consider enforcement's effects on business objectives. We identify the notion of obstruction, which generalizes deadlock within a system where access control is enforced, and we formulate the existence of an obstruction-free enforcement mechanism as a decision problem. We present lower and upper bounds for the complexity of this problem and also give an approximation algorithm that performs well when authorizations are equally distributed among users.","PeriodicalId":364995,"journal":{"name":"2011 IEEE 24th Computer Security Foundations Symposium","volume":"184 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132277518","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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