Adversarial Capabilities Research Articles

Rateless Codes for AVC Models

The arbitrarily varying channel (AVC) is a channel model whose state is selected maliciously by an adversary. Fixed-blocklength coding assumes a worst-case bound on the adversary's capabilities, which leads to pessimistic results. This paper defines a variable-length perspective on this problem, for which achievable rates are shown that depend on the realized actions of the adversary. Specifically, rateless codes are constructed which require a limited amount of common randomness. These codes are constructed for two kinds of AVC models. In the first the channel state cannot depend on the channel input, and in the second it can. As a by-product, the randomized coding capacity of the AVC with state depending on the transmitted codeword is found and shown to be achievable with a small amount of common randomness. The results for this model are proved using a randomized strategy based on list decoding.

Survey of anonymity communication

Anonymity communication is a hot topic in the area of network and communication.The origin of anonymity communication was first outlined,and the framework of anonymity communication in terms of anonymity property,adversary capability and network type were described.Then the research of anonymity communication was investigated,and a brief description of several major anonymity communication systems including Anonymizer,Tor,Mixminion,Crowds and Tarzan was provided.Finally the challenges confronted in the development of anonymity communication were proposed,including the user experience of anonymity communication,credibility evaluation system of relay node and misbehavior of anonymity communication.

Channel abstractions for network security

Process algebraic techniques for distributed systems are increasingly being targeted at identifying abstractions that are adequate for both high-level programming and specification and security analysis and verification. Drawing on our earlier work in Bugliesi and Focardi, (2008), we investigate the expressive power of a core set of security and network abstractions that provide high-level primitives for specifying the honest principals in a network, while at the same time enabling an analysis of the network-level adversarial attacks that may be mounted by an intruder.We analyse various bisimulation equivalences for security that arise from endowing the intruder with: (i)different adversarial capabilities; and(ii)increasingly powerful control over the interaction among the distributed principals of a network. By comparing the relative strength of the bisimulation equivalences, we obtain a direct measure of the intruder's discriminating power, and hence of the expressiveness of the corresponding intruder model.

On the Topology of Discrete Strategies

In this paper we explore a topological perspective of planning in the presence of uncertainty, focusing on tasks specified by goal states in discrete spaces. We introduce strategy complexes. A strategy complex is the collection of all plans for attaining all goals in a given space. Plans are like jigsaw pieces. Understanding how the pieces fit together in a strategy complex reveals structure. That structure characterizes the inherent capabilities of an uncertain system. By adjusting the jigsaw pieces in a design loop, one can build systems with desired competencies. The paper draws on representations from combinatorial topology, Markov chains, and polyhedral cones. Triangulating between these three perspectives produces a topological language for describing concisely the capabilities of uncertain systems, analogous to the concepts of reachability and controllability in other disciplines. The major nouns in this language are topological spaces. Three key theorems illustrate the sentences in this language. (a) Goal attain-ability: There exists a strategy for attaining a particular goal from anywhere in a system if and only if the strategy complex of a slightly modified system is homotopic to a sphere. (b) Full controllability : A system can move between any two states despite control uncertainty precisely when its strategy complex is homotopic to a sphere of dimension two less than the number of states. (c) General structure: Any system’s strategy complex is homotopic to the product of a spherical part, modeling full controllability on subspaces, and a general part, modeling adversarial capabilities. This paper contains a number of additional results required as stepping stones, along with many examples. We provide algorithms for computing the key structures described. Finally, we show that some interesting questions are hard. For instance, it is NP-complete to determine the most precisely attainable goal of a system with perfect sensing, but uncertain control.

On the Modeling of Honest Players in Reputation Systems

Reputation mechanisms are a key technique to trust assessment in large-scale decentralized systems. The effectiveness of reputation-based trust management fundamentally relies on the assumption that an entity's future behavior may be predicted based on its past behavior. Though many reputation-based trust schemes have been proposed, they can often be easily manipulated and exploited, since an attacker may adapt its behavior, and make the above assumption invalid. In other words, existing trust schemes are in general only effective when applied to honest players who usually act with certain consistency instead of adversaries who can behave arbitrarily. In this paper, we investigate the modeling of honest entities in decentralized systems. We build a statistical model for the transaction histories of honest players. This statistical model serves as a profiling tool to identify suspicious entities. It is combined with existing trust schemes to ensure that they are applied to entities whose transaction records are consistent with the statistical model. This approach limits the manipulation capability of adversaries, and thus can significantly improve the quality of reputation-based trust assessment.

Security Abstractions and Intruder Models (Extended Abstract)

Process algebraic specifications of distributed systems are increasingly being targeted at identifying security primitives well-suited as high-level programming abstractions, and at the same time adequate for security analysis and verification. Drawing on our earlier work along these lines [Bugliesi, M. and R. Focardi, Language based secure communication , in: Proceedings of the 21st IEEE Computer Security Foundations Symposium, CSF 2008, Pittsburgh, Pennsylvania, 23-25 June 2008 (2008), pp. 3–16], we investigate the expressive power of a core set of security and network abstractions that provide high-level primitives for the specifications of the honest principals in a network as well as the lower-level adversarial primitives that must be assumed available to an attacker. We analyze various bisimulation equivalences for security, arising from endowing the intruder with ( i ) different adversarial capabilities and ( ii ) increasingly powerful control on the interaction among the distributed principals of a network. By comparing the relative strength of the bimimulation equivalences we obtain a direct measure of the discriminating power of the intruders, hence of the expressiveness of the corresponding models.

Certificateless Threshold Ring Signature

We propose a t-out-of- n Certificateless Threshold Ring Signature (CL-TRS) scheme and prove its security under a new and stronger set of security models. The models capture a new adversarial capability called User Partial Key Replacement Attack, which has been considered practical and realistic but has never been formalized before. The new scheme requires only a constant number of bilinear pairing operations for signature verification. It also has a compact signature size which is linear to the number of non-signers (i.e. n − t) rather than that of actual signers. We also propose a 1-out-of- n CL-TRS (i.e. a certificateless ring signature scheme) which has the most efficient verification among all the certificateless ring signature schemes currently known.

Does Secure Password-Based Authenticated Key Exchange against Leakage of Internal States Exist?

In this paper, we raise a question about existence of secure password-based authenticated key exchange against leakage of internal states (i.e., the passwords and session-specific private information). Toward this question, first, we classify six models of adversary's capabilities about leakage. Next, as a result of considerations for 2-party PAKE, we find two negative answers, but also find a positive answer. More specifically, we show that there exists no scheme which is secure in strong leakage models, but we also show that there exists a scheme which is secure in weak leakage models. Also, we consider the case of 3-party setting which is a special setting of password-based authenticated key exchange, and we find similar impossibilities as 2-party setting.

On the relation among various security models for certificateless cryptography

Certificateless cryptography is a promising technology for solving the key escrow problem in identity-based cryptography. However, the lack of a unified set of definitions and security models currently hinders its progression as much effort has been put on refining the definitions and looking for an appropriate and practical security models. In this article, we aim to contribute on unifying the definitions and security models for Certificateless Encryption (CLE) schemes. First, we show that the original seven-algorithm definition is equivalent to a simplified five-algorithm definition. We believe that this simplified definition may lead to more compact and efficient implementations in practice and also help in the effort of standardisation of CLE. Secondly, we show that a CLE scheme cannot be both malicious Key Generation Center (KGC) secure and strongly secure in the standard model. Due to the practicality and attacking significance of malicious KGC security; and the uncertainty of how practical the strong security is, we, therefore, suggest constructing practical CLE schemes to be malicious KGC secure. Finally, we propose to formalise a new adversarial capability called partial key replacement attack into the security models and show that our generic scheme proposed recently is secure against this new type of attacks.

Resource-aware protocols for authenticated group key exchange in integrated wired and wireless networks

Protocols for group key exchange are cryptographic algorithms that describe how a group of parties communicating over a public network can come up with a common secret key. Due to their critical role in building secure multicast channels, a number of group key exchange protocols have been proposed over the years in a variety of settings. However despite many impressive achievements, there seems to have been no previous systematic look at the growing problem of key exchange over integrated wired and wireless (IWW) networks which consist of two distinct types of users: users having low-performance mobile devices with some form of battery power and users having high-performance stationary computers with no power constraint. The contribution of the present work is to fill this deficiency by providing a secure and efficient protocol for resource-aware group key exchange over the rapidly expanding IWW networks. By evenly spreading much of the total amount of computation across high power users, our protocol avoids any potential performance bottleneck of the system while keeping the burden on low power users at minimal. Our protocol also achieves provable security against powerful active adversaries under the decisional Diffie–Hellman assumption. We provide a rigorous proof of security for the protocol in a well-defined formal model of communication and adversarial capabilities.

Universally Composable Security Concurrent Deniable Authentication Based on Witness Indistinguishable

A new approach and an idea for exploration are presented to the concurrent deniable authentication based on witness-indistinguishable (WI) within the framework of universally composable (UC) security. A definition of an ideal functionality for deniable authentication is formulated. A new deniable authentication protocol is proposed based on two primitives of the verifiably smooth projective Hashing (VSPH) and non-committing encryptions (NCE). This new approach is practically relevant to VSPH based on the Decisional Diffie-Hellman (DDH) assumption and NCE based on the decisional composite residuosity (DCR) assumption. Compared with a timing constraint and public directory model, simulation of the concurrent protocols is not needed to restrict an adversary capability in a common reference string (CRS) model. The protocols are forward deniable and UC security against adaptive adversaries. Unlike previous proposals with the CCA2 public-key cryptosystem or multi-trapdoor commitments paradigm, the new paradigm leads to more efficient protocols.

Security weakness in a three-party pairing-based protocol for password authenticated key exchange

Authentication and key exchange are fundamental for establishing secure communication channels over public insecure networks. Password-based protocols for authenticated key exchange are designed to work even when user authentication is done via the use of passwords drawn from a small known set of values. Recently, Wen et al. (H.-A. Wen, T.-F. Lee, T. Hwang, Provably secure three-party password-based authenticated key exchange protocol using Weil pairing, IEE Proceedings—Communications 152 (2) (2005) 138–143) proposed a new protocol for password-based authenticated key exchange in the three-party setting, where the clients trying to establish a common secret key do not share a password between themselves but only with a trusted server. Wen et al.’s protocol carries a claimed proof of security in a formal model of communication and adversarial capabilities. However, this work shows that the protocol for three-party key exchange is completely insecure and the claim of provable security is seriously incorrect. We conduct a detailed analysis of flaws in the protocol and its security proof, in the hope that no similar mistakes are made in the future.

Assessing risks from threats to process plants: Threat and vulnerability analysis

AbstractProcess security management addresses threats from terrorist and criminal acts against plants that may result in the release of hazardous materials. The risk of such threats must be assessed to determine if existing security measures and safeguards are adequate or need improvement. Risk assessment is the heart of a process security program. Process plants need straight forward and easily applied methods to assess security risks using techniques that can be employed in a variety of situations and at varying levels of detail. This paper describes an approach that accomplishes these objectives.Threat analysis is the first step. It is used to identify the sources and types of threats and their likelihood. The approach described in this paper involves the consideration of motivations and capabilities of adversaries and the rating of facility security factors to develop a threat profile. Once specific threats have been identified, process vulnerability analysis is used to identify threat scenarios, i.e., how threats could be realized. Plants and processes are divided into sectors, and each credible threat within each sector is considered. Vulnerabilities are identified by brainstorming the ways barriers can be penetrated and process containment breached. Checklists are used to guide the brainstorming, and scenario consequences are recorded. Existing security measures and safeguards are listed, and any recommendations for improvements to reduce the likelihood and severity of terrorist and criminal acts are made for consideration by management based on the nature of the threat, process vulnerabilities, possible consequences, and existing security measures and safeguards. Risk rankings are performed as part of the analyses.

Threat analysis: Defining the adversary

Threat analysis seeks to understand the motives and capabilities of adversaries who may be targeting your corporation's critical information. These potential assailants include domestic or foreign corporations, foreign intelligence services, anti-business activists, criminals, and terrorists. The key to threat analysis as a way of managing security risks is to adopt an adversary's perspective. The author describes where threat analysis fits into the overall operations security/risk management process and discusses ways of identifying critical information and vulnerabilities, performing a risk assessment, and applying countermeasures. © 1998 John Wiley & Sons, Inc.

Supercomputers: Enhance strategic decision‐making: An interview with Richard J. Pryor

Approaching a broad spectrum of problems also helps us to attract the best talent and develop our computers to be most useful for both governmental and commercial purposes. And, of course, we cannot overlook the strategic advantage of having the best economic models available for national security purposes. Economic models can help us to better determine military capability of potential adversaries, whether nations or major terrorist groups, and to accurately determine the effect of counter measures such as trade sanctions.

Culture and Misperception: The Law and the Press in the Outbreak of War in 1803

Studies cultural preconceptions, derived from decision-makers' own political systems and projected on to others, affect their perceptions of other people's actions. Thus, one observer of the Fourth Republic suggests that 'members of the French political class frequently act in the field of foreign affairs as if their foreign counterparts were so like themselves that the issue at stake could be treated as a domestic issue'.1 However, it is often impossible to identify the ways in which national traditions affect perception, as cultural assumptions, usually taken for granted, are rarely recorded: as the result, most case-studies ignore them.2 This study of the breakdown of the peace of Amiens in 1802-3 analyses the misperceptions that arose from the cultural differences between France and Great Britain. James L. Richardson divides misperception in international crises into four analytical categories: misperception of an adversary's capabilities; of its intentions; of the likely effects of one's own actions; and of the capacity, intention, or response of third parties.3 Of the four, only the second and third misperception of one's adversary's intentions and of the likely repercussions of one's own actions affected the peace of Amiens.4 And although three types of issue caused tension between France and Britain in 1802-3 ~ territorial and strategic; emigres and the press; and commercial and colonial only misperceptions deriving from the first two led to the

A new defence construct: ‘rapid dominance’

Now that the confrontation with the Eastern bloc has dimimshed, the threats to security are likely to come from less predictable areas, such as terrorism, drugs and other areas of organised crime, with peacekeeping and humanitarian aid operations increasingly be coming the norm. Here Dr Harlan Ullman propounds a new concept for dealing with this wide range of threats’. Unlike the current American doctrine of overwhelming force, the focal point for attack in the future should be wider than the purely military encompassing the will and mind of the adversary. Rapid Dominance could provide a complete concept for controlling and even eliminating some of these newer threats with the psychological dominance of the enemy possibly negating direct conflict. Should this approach fail, ‘Rapid Dominance would also have the capability of imposing over whelming force against the full spectrum of an adversary's military capabilities.

Soldier Spies: Israeli Military Intelligence (review)

150 SHOFAR Fall 1994 Vol. 13, No. 1 Soldier Spies: Israeli Military Intelligence, by Samuel M. Katz. Novato, CA: Presidio Press, 1992. 389 pp. $21.95. Because of the regularity of war throughout history, the need for information regarding a potential adversary's capabilities and intentions can be traced back to ancient times. Even as the Israelites wandered in the Sinai, the Lord commanded Moses to send two men into Canaan to spy out the land. The results of this venture were illuminating. The reports of the spies were contradictory and led to considerable division about what action the Israelites were to take, illustrating the still vital problem of how to interpret intelligence, a problem that has grown in complexity as the sources of intelligence procurement have multiplied. But accurate and timely intelligence, properly assessed, remains vital for the survival of the State of Israel, surrounded by strong and hostile neighbors. There have been a considerable number of studies of Israeli intelligence , but scholarly study of military intelligence is made difficult by several factors, including the reluctance of all governments to release any documents regarding intelligence matters and even to deny the very existence of some intelligence agencies, personnel, and methods. The explanation for this continued secrecy is rooted not only in the need to protect agents and informants (HUMINT), but also in the desire to protect the sophisticated technological means of procuring intelligence, mainly signals intelligence (SIGlN'I) and electronic intelligence (ELI NT). Structured loosely on the United States model, the Israeli intelligence community consists of three major branches: the Mossad, the foreign espionage agency; Shin Bel, concerned with internal counterintelligence, and lastly A 'man, the intelligence branch, and now a separate corps, of the Israeli Defense Forces (IDF). While functional, in Israel, as everywhere, this arrangement is complicated by clashing personal and institutional rivalries and ambitions, panly the result of an inevitable overlap in functions. This has resulted in some bitter personal and inter-branch feuds, the duplication of efforts, sometimes leading to misinterpretations, and on occasion even cynical betrayals. According to Katz, the military intelligence branch, A'man, recently formed into a separate corps within the IDF, has been and remains the most important instrument safeguarding the state's security, helping to offset by superior intelligence the superior forces ofIsrael's Arab enemies. Although they arc not part of the official military inteligence establishment, the author includes some activities of the IDF Special Forces, especially the Book Reviews 151 small' elite reconnaisance units (Sayerot) attached to the three major commands and to the General Staff, and their predecessors in the Haganah, a justifiable inclusion since procurement of intelligence data often constituted a major objective of Israeli special operations. This book is a "good read" but hardly a definitive history of Israeli military intelligence. For the reasons cited above, these activities must remain shrouded in secrecy for many years and even decades, and the author has relied heavily on published materials, an obvious but perhaps unavoidable limitation. Nonetheless, Katz does not hesitate to assign blame for some great and small blunders. His assessment of some of the early military intelligence commanders, especially of Isser Beeri, a man of "unbridled zealousness" is quite correct (pp. 47-49). Not all Israeli intelligence officers or activities were beyond reproach. Troubling to the reviewer, however, were several mistakes revealing carelessness or the author's limited understanding of higher 'military organization and orders of battle. To cite one example: in February 1960, violating the agreement limiting military deployment in the Sinai, Nasser moved three infantry brigades as well as "elements of the 4th Armored Division ... more than five-hundred Egyptian T-54/55 main battle tanks" to the frontier with Israel, a move undetected by A'man for several days (p. 149). The failure of Israeli military intelligence, then headed by Chaim Herzog, is not disputed, but no Egyptian armored division, or for that matter any armored division in the world, ever numbered 500 main battle tanks. And given that the publisher specializes in military history, this raises doubts not only about the author, but perhaps even more about the editing of the book. Such misgivings are further confirmed by some careless use...

Capabilities, Allocations, and Success in Militarized Disputes and Wars, 1816-1976

This article examines the relationship between the material capabilities of adversaries, their allocation of resources to the military, and the outcomes of wars and militarized disputes, 1815–1976. Using data from the Correlates of War project, the authors compare the military, industrial, and demographic capabilities of the two sides in wars and in militarized disputes involving major powers. They find that an advantage in industrial capabilities is more strongly associated with victory than is an advantage in military or demographic capabilities. Turning to the allocation of resources to the military, the authors consider: (a) the military expenditures of each side in proportion to its industrial capability, and (b) the military personnel as a fraction of the total population. As for the latter, a heavier allocation is associated with victory in war but defeat in disputes. Less ambiguous and more suggestive, a heavier allocation of expenditure to the military is associated with defeat in both wars and in disputes.