Symbolic Security Research Articles

Automated verification of Telegram’s MTProto 2.0 in the symbolic model

MTProto 2.0 is the suite of security protocols for instant messaging at the core of the popular Telegram messenger application. In this paper we analyse MTProto 2.0 using ProVerif, a state-of-the-art symbolic security protocol verifier based on the Dolev–Yao model. We provide the first formal symbolic model of MTProto 2.0; in this model, we provide fully automated proofs of the soundness of authentication, normal chat, end-to-end encrypted chat, and rekeying mechanisms with respect to several security properties, including authentication, integrity, secrecy and perfect forward secrecy. At the same time, we discover that the rekeying protocol is vulnerable to an unknown key-share (UKS) attack. To achieve these results, we proceed in an incremental way: each protocol is examined in isolation, relying only on the guarantees provided by the previous ones and the robustness of the basic cryptographic primitives. The importance of this research is threefold. First, it proves the formal correctness of MTProto 2.0 with respect to most relevant security properties. Secondly, we isolate the aspects of cryptographic primitives that escape the symbolic model and thus require further investigation in the computational model. Finally, our modelisation can serve as a reference for the implementation and analysis of clients and servers.

Registrované partnerství a homoparentalita v Česku

This paper introduces a unique and comprehensive sociological analysis of same-sex partnerships in the Czech Republic, especially in the legally recognised (though limited) form of civil unions (registered partnerships - RP). The analysis combines multiple data sources and methodological approaches, drawing on administrative data from the Ministry of Internal Affairs (n=2710), secondary quantitative data from the Czech Statistical Office and Public Opinion Research Centre/CVVM, and original quantitative (n=882) and qualitative (n=48) data. Focusing on the heteronormative framing of the issue, two main aspects come to the forefront: gender and LGBT parenting. Data show that there has been a small but steadily growing amount of interest in RP, especially among women, in the last six years. However, RP remains very selective and quite 'unpopular'. Although there has been a weakening of the procreative function of marriage, the role of RP in this respect is less clear-cut. On the one hand, it makes some paths to becoming a parent more difficult, while on the other, for some people, it provides a certain symbolic security for their existing family. The article also explores other gender and age characteristics and differences or similarities to marriage.

Domesticating Danger: Coping Codes and Symbolic Security amid Violent Organized Crime in Mexico

Sociologists have long debated how labels are deployed to construct and exaggerate social threats but have yet to consider their use to cope with danger. I draw on qualitative fieldwork conducted in the midst of a gruesome turf war in Monterrey, Mexico, to conceptualize coping codes. These defensive labels emerge in everyday conversation and allow its users to allude to threatening actors without being explicit—in this case, violent organized crime labeled malitos, or little evil guys. They emerge from below and in relation to top-bottom labeling processes they can both challenge and reproduce. Coping codes provide symbolic security by minimizing danger, although at a cost when also used to draw symbolic boundaries between the living and the dead “accused of being into something.” The case calls for further research on coping codes in dangerous contexts, particularly at the onset of unsettled times when people tend to minimize rupture.

Regulating the Wild West: Symbolic Security Bubbles and White Collar Crime in the Art Market

The study of crime and criminality in the art market has received increasing attention within criminology, however little has been written on the criminogenic values built into the structure of the art market. Despite increasing legislation to counteract instances of money laundering and fraud, the legal governance of the art market brings such ambiguity that actors in the market have formed their own responses to managing risk. In this article, we discuss how these actors rely on security bubbles and self-regulation and how this can have the unfortunate effect of adding to a criminogenic art market where white-collar crime is sustained. The dependence on self-policing created a field where powerful elites run things, and traditional policing agents have little purchase.

A Hierarchical Multicast Key Distribution Protocol

In secure group communication, group keys (GK) are used to ensure the confidentiality of communication. The group key distribution (GKD) is responsible for updating and distributing new group keys when the group membership changes. Most well-known GKD protocols are based on a logical key hierarchy (LKH), where only one group controller (GC) is used. These protocols have various issues, including a single point of failure, meaning that the GC often has a huge workload and can be easily overwhelmed. In this paper, we propose a hierarchical multicast key distribution protocol that supports multi-level controllers to manage a group. Each controller just needs to manage the next-level nodes, and if one fails, the superior controller can replace it with minimal work. The proposed protocol effectively balances the work of controllers, greatly improves the reliability of the group key distribution, and also allows group members to build dynamic conferences without controllers. We provide a security proof of the proposed protocol in a symbolic security model and compare it to other protocols in terms of efficiency, functionality, and security.

Secure memory erasure in the presence of man-in-the-middle attackers

Memory erasure protocols serve to clean up a device’s memory before the installation of new software. Although this task can be accomplished by direct hardware manipulation, remote software-based memory erasure protocols have emerged as a more efficient and cost-effective alternative. Existing remote memory erasure protocols, however, still rely on non-standard adversarial models to operate correctly, thereby requiring additional hardware to restrict the adversary’s capabilities. In this work, we provide a formal definition of secure memory erasure within a symbolic security model that utilizes the standard Dolev–Yao adversary. Our main result consists of a restriction on the Dolev–Yao adversary that we prove necessary and sufficient to solve the problem of finding a protocol that satisfies secure memory erasure. We also provide a description of the resulting protocol using standard cryptographic notation, which we use to analyze the security and communication complexity trade-off commonly present in this type of protocols.

Does Evidence-Based EU Law Survive the Covid-19 Pandemic? Considering the Status in EU Law of Lockdown Measures Which Affect Free Movement

When Member States restrict free movement on public health grounds they must show that their measures have a sound scientific basis. However, during the pandemic Member States have imposed a wide variety of restrictions, at the border, and internally. While Member State governments have invariably had local scientific advice, the variety of their measures suggests that their actions have also been driven, to some extent, by public opinion, contrary to what EU law generally allows. This situation could be seen as a defeat for EU law as traditionally conceived, and the triumph of local preferences over scientific standards. Perhaps we learn that in a crisis, local desires for symbolic security and closure trump both law and science. Alternatively, it can be argued that the Court of Justice's emphasis on exclusively objective justifications for measures is unrealistic and over-strict. The pandemic responses show that (i) science is often neither clear nor determinative, and (ii) policy is invariably a mix of science and values, even in apparently technical fields. In either case, the absence of legal challenges to Member State actions leaves free movement in an uncertain state. Have we entered a new phase, where national fears are a more legitimate justification for restricting movement, or will the pandemic be treated as so exceptional as to be beyond law, and thus not a precedent?

The limits of post-genocide justice in Rwanda: assessing gacaca from the perspective of survivors

ABSTRACT In 2002 the Rwandan government asked thousands of untrained civilians to organize, staff, and operate the largest judicial experiment in human history: the gacaca courts. For nearly a decade, community residents met weekly to judge the fates of accused genocidaires. Critical to this process were survivors who acted as judges, provided testimony, and bore witness to the Rwandan government’s response to genocide. This paper documents the findings from qualitative fieldwork in Rwanda exploring survivor perceptions of the gacaca process and outcomes. In total, 57 stakeholders were interviewed and asked about their perspectives on the court’s procedures, limitations, accomplishments, and legacy. Results from this study indicate that although survivors desired and expected a variety of justice-related outcomes from the courts, including punishment for those responsible, material and symbolic reparations, peace and security, in the end, many were disappointed. Nevertheless, as the process wore on, many survivors continued to support gacaca’s operation because they believed it was the only way they could shape post-genocide narratives about Rwanda’s past, present and future. Ultimately this paper presents a more complex picture of how those on the ground understood the gacaca process.

Does Evidence-Based EU Law Survive the COVID-19 Pandemic? Considering the Status in EU Law of Lockdown Measures Which Affect Free Movement

When Member States restrict free movement on public health grounds they must show that their measures have a sound scientific basis. However, during the pandemic Member States have imposed a wide variety of restrictions, at the border, and internally. While Member State governments have invariably had local scientific advice, the variety of their measures suggests that their actions have also been driven, to some extent, by public opinion, contrary to what EU law generally allows. This situation could be seen as a defeat for EU law as traditionally conceived, and the triumph of local preferences over scientific standards. Perhaps we learn that in a crisis, local desires for symbolic security and closure trump both law and science. Alternatively, it can be argued that the Court of Justice's emphasis on exclusively objective justifications for measures is unrealistic and over-strict. The pandemic responses show that (i) science is often neither clear nor determinative, and (ii) policy is invariably a mix of science and values, even in apparently technical fields. In either case, the absence of legal challenges to Member State actions leaves free movement in an uncertain state. Have we entered a new phase, where national fears are a more legitimate justification for restricting movement, or will the pandemic be treated as so exceptional as to be beyond law, and thus not a precedent?

The Assassination of Anwar al-Sadat: An Intelligence Failure

Within the context of intelligence, the assassination of Egypt's President Muhammad Anwar al-Sadat on 6 October 1981 can be characterized as both a symbolic security failure and a failure to implem...

Intersectionality, subjectivity, collectivity and the union: a study of the ‘locked-out’ hotel workers in Toronto

The study uses narrative analysis to understand the workers discursive constructions of their classed, gendered and racialized subjective identities and their investments into the collectivity of the union in the context of the lock-out. It goes beyond the Marxian analysis and uses poststructural feminist analysis to understand how the intersectional subjective identities are constituted and their interrelationship to the investments in and constitution of collectivities in the context of industrial action. The study is based on participant observation and interviews of hotel workers in the food and beverage section of a hotel in Toronto, who were locked-out in 2007, and of other workers on the picket line supporting the locked-out workers. These workers are members of UNITE HERE-Local 75 (Now HERE-Local 75), who had been in the process of renewal of their contracts at the time. I would argue that the intersectional subjectivities of the hotel workers and their investments in the collectivity of the union are fluid and relate to their pursuit of material and/or symbolic security through search for an identity as a unionized, active worker or an identity which is secure irrespective of the union.

Computationally sound symbolic security reduction analysis of the group key exchange protocols using bilinear pairings

The security of the group key exchange protocols has been widely studied in the cryptographic community in recent years. Current work usually applies either the computational approach or the symbolic approach for security analysis.The symbolic approach is more efficient than the computational approach, because it can be easily automated. However, compared with the computational approach, it has to overcome three challenges: (1) The computational soundness is unclear; (2) the number of participants must be fixed; and (3) the advantage of efficiency disappears, if the number of participants is large.This paper proposes a computationally sound symbolic security reduction approach to resolve these three issues. On one hand, combined with the properties of the bilinear pairings, the universally composable symbolic analysis (UCSA) approach is extended from the two-party protocols to the group key exchange protocols. Meanwhile, the computational soundness of the symbolic approach is guaranteed. On the other hand, for the group key exchange protocols which satisfy the syntax of the simple protocols proposed in this paper, the security is proved to be unrelated with the number of participants. As a result, the symbolic approach just needs to deal with the protocols among three participants. This makes the symbolic approach has the ability to handle arbitrary number of participants. Therefore, the advantage of efficiency is still guaranteed. The proposed approach can also be applied to other types of cryptographic primitives besides bilinear pairing for computationally sound and efficient symbolic analysis of group key exchange protocols.

Collusion-Resistant Multicast Key Distribution Based on Homomorphic One-Way Function Trees

Providing security services for multicast, such as traffic integrity, authentication, and confidentiality, requires securely distributing a group key to group receivers. In the literature, this problem is called multicast key distribution (MKD). A famous MKD protocol-one-way function tree (OFT)-has been found vulnerable to collusion attacks. Solutions to prevent these attacks have been proposed, but at the cost of a higher communication overhead than the original protocol. In this paper, we prove falsity of a recently-proposed necessary and sufficient condition for a collusion attack on the OFT protocol to exist by a counterexample and give a new necessary and sufficient condition for nonexistence of any type of collusion attack on it. We instantiate the general notion of OFT to obtain a particular type of cryptographic construction named homomorphic one-way function tree (HOFT). We propose two structure-preserving graph operations on HOFTs, tree product and tree blinding. One elegant quality possessed by HOFTs is that handling (adding, removing, or changing) leaf nodes in a HOFT can be achieved by using tree product without compromising its structure. We provide algorithms for handling leaf nodes in a HOFT. Employing HOFTs and related algorithms, we put forward a collusion-resistant MKD protocol without losing any communication efficiency compared to the original OFT protocol. We also prove the security of our MKD protocol in a symbolic security model.

Universally Composable Symbolic Security Analysis

In light of the growing complexity of cryptographic protocols and applications, it becomes highly desirable to mechanize—and eventually automate—the security analysis of protocols. A natural step towards automation is to allow for symbolic security analysis. However, the complexity of mechanized symbolic analysis is typically exponential in the space and time complexities of the analyzed system. Thus, full automation via direct analysis of the entire given system has so far been impractical even for systems of modest complexity. We propose an alternative route to fully automated and efficient security analysis of systems with no a priori bound on the complexity. We concentrate on systems that have an unbounded number of components, where each component is of small size. The idea is to perform symbolic analysis that guarantees composable security. This allows applying the automated analysis only to individual components, while still guaranteeing security of the overall system. We exemplify the approach in the case of authentication and key-exchange protocols of a specific format. Specifically, we formulate and mechanically assert symbolic properties that correspond to concrete security properties formulated within the Universally Composable security framework. As an additional contribution, we demonstrate that the traditional symbolic secrecy criterion for key exchange provides an inadequate security guarantee (regardless of the complexity of verification) and propose a new symbolic criterion that guarantees composable concrete security.

A computational analysis of the Needham–Schroeder–(Lowe) protocol

The Needham Schroeder protocol and its repaired verdion due to Lowe are the main test cases used by symbolic methods for cryptographic protocol analysis. In this paper we proved the first computational analysis of the protocol. We start by translating Lowe's attack against the orginal protocol into the computational framework that we use in our analysis. Then we prove that the repaired protocol may not be secure. even when the encryption scheme that is used in its implementation satisfies indistinguishability under chosen-plaintext attack, This shows that symbolic security analysis is not sound for protocols that use this kind of encryption. Our main result is to prove that the Needham-schroeder-Lowe protocol is secure if it is Implemented with an encryption scheme that satisfies the stronger notion of indistinguishability under chosen-ciphertext attack.

Beyond Good and Evil? A Buddhist critique of Nietzsche

Abstract In what ways was Nietzsche right, from a Buddhist perspective, and where did he go wrong? Nietzsche understood how the distinction we make between this world and a higher spiritual realm serves our need for security, and he saw the bad faith in religious values motivated by this need. He did not perceive how his alternative, more aristocratic values, also reflects the same anxiety. Nietzsche realised how the search for truth is motivated by a sublimated desire for symbolic security; philosophy's attempt to create the world reflects the tyrannical will‐to‐power, becoming the most ‘spiritualised’ version of the need to impose our will. Insofar as truth is our intellectual effort to grasp being symbolically, however, Nietzsche overlooks a different reversal of perspective which could convert the ‘bad infinite’ of heroic will into the good infinite of disseminating play. What he considered the crown of his system—eternal recurrence—is actually its denouement. Having seen through the delusion of Being...