Cryptography ensures the confidentiality and authenticity of information but often relies on unproven assumptions. SAT solvers are a powerful tool to test the hardness of certain problems and have successfully been used to test hardness assumptions. This paper extends a SAT solver to efficiently work on cryptographic problems. The paper further illustrates how SAT solvers process cryptographic functions using automatically generated visualizations, introduces techniques for simplifying the solving process by modifying cipher representations, and demonstrates the feasibility of the approach by solving three stream ciphers.

To optimize a SAT solver for cryptographic problems, we extended the solver's input language to support the XOR operation that is common in cryptography. To better understand the inner workings of the adapted solver and to identify bottlenecks, we visualize its execution. Finally, to improve the solving time significantly, we remove these bottlenecks by altering the function representation and by pre-parsing the resulting system of equations.

The main contribution of this paper is a new approach to solving cryptographic problems by adapting both the problem description and the solver synchronously instead of tweaking just one of them. Using these techniques, we were able to solve a well-researched stream cipher 26 times faster than was previously possible.

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Extending SAT Solvers to Cryptographic Problems

In modern computer systems, user processes are isolated from each other by the operating system and the hardware. Additionally, in a cloud scenario it is crucial that the hypervisor isolates tenants from other tenants that are co-located on the same physical machine. However, the hypervisor does not protect tenants against the cloud provider and thus the supplied operating system and hardware. Intel SGX provides a mechanism that addresses this scenario. It aims at protecting user-level software from attacks from other processes, the operating system, and even physical attackers.

Malware Guard Extension: Using SGX to Conceal Cache Attacks

While the general definition of the Internet of Things (IoT) is almost mature, roughly defining it as an information network connecting virtual and physical objects, there is a consistent lack of consensus around technical and regulatory solutions. There is no doubt, though, that the new paradigm will bring forward a completely new host of issues because of its deep impact on all aspects of human life. In this work, the authors outline the current technological and technical trends and their impacts on the security, privacy, and governance. The work is split into short- and long-term analysis where the former is focused on already or soon available technology, while the latter is based on vision concepts. Also, an overview of the vision of the European Commission on this topic will be provided.

An Overview of Privacy and Security Issues in the Internet of Things

Static analysis of software with deductive methods is a highly dynamic field of research on the verge of becoming a mainstream technology in software engineering. It consists of a large portfolio of - mostly fully automated - analyses: formal verification, test generation, security analysis, visualization, and debugging. All of them are realized in the state-of-art deductive verification framework KeY. This book is the definitive guide to KeY that lets you explore the full potential of deductive software verification in practice. It contains the complete theory behind KeY for active researchers who want to understand it in depth or use it in their own work. But the book also features fully self-contained chapters on the Java Modeling Language and on Using KeY that require nothing else than familiarity with Java. All other chapters are accessible for graduate students (M.Sc. level and beyond). The KeY framework is free and open software, downloadable from the book companion website which contains also all code examples mentioned in this book.

Deductive Software Verification - The KeY Book

RFID (Radio Frequency Identification) systems are one of the most pervasive computing technologies with technical potential and profitable opportunities in a diverse area of applications. Among their advantages is included their low cost and their broad applicability. However, they also present a number of inherent vulnerabilities. This paper develops a structural methodology for risks that RFID networks face by developing a classification of RFID attacks, presenting their important features, and discussing possible countermeasures. The goal of the paper is to categorize the existing weaknesses of RFID communication so that a better understanding of RFID attacks can be achieved and subsequently more efficient and effective algorithms, techniques and procedures to combat these attacks may be developed.

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Classifying RFID attacks and defenses

The mifare Classic is a contactless smart card that is used extensively in access control for office buildings, payment systems for public transport, and other applications. We reverse engineered the security mechanisms of this chip: the authentication protocol, the symmetric cipher, and the initialization mechanism. We describe several security vulnerabilities in these mechanisms and exploit these vulnerabilities with two attacks; both are capable of retrieving the secret key from a genuine reader. The most serious one recovers the secret key from just one or two authentication attempts with a genuine reader in less than a second on ordinary hardware and without any pre-computation. Using the same methods, an attacker can also eavesdrop the communication between a tag and a reader, and decrypt the whole trace, even if it involves multiple authentications. This enables an attacker to clone a card or to restore a real card to a previous state.

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Dismantling MIFARE Classic

Several countermeasures against side-channel analysis result in misalignment of power traces, in order to make DPA more difficult. In this paper we propose a new algorithm to align the measurements after this desynchronizing through the variations of the internal clock, random delays, etc. The algorithm is based on the ideas of SIFT and U-SURF algorithm that were originally proposed for image recognition. The comparison with other known methods favors our solution in terms of efficiency and computational complexity.

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RAM: rapid alignment method

On March 7, 2008 researchers and students of the Digital Security group of the Radboud University Nijmegen have discovered a serious security flaw in a widely used type of contactless smartcard [9], also called RFID tag. It concerns the ”Mifare Classic” RFID card produced by NXP (formerly Philips Semiconductors). Earlier, German researchers Karsten Nohl en Henryk Pltz pointed out security weaknesses of this cards. Worldwide around 1 billion of these cards have been sold. This type of card is used for the Dutch ‘ov-chipkaart’ [the RFID card for public transport throughout the Netherlands] and public transport systems in other countries (for instance the subway in London). Mifare cards are also widely used as company cards to control access to buildings and facilities. All this means that the flaw has a broad impact. Because some cards can be cloned, it is in principle possible to access buildings and facilities with a stolen identity. This has been demonstrated on an actual system. In many situations where these cards are used there will be additional security measures; it is advisable to strengthen these where possible. The Digital Security group found weaknesses in the authentication mechanism of the Mifare Classic. In particular:

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Ruben Muijrers

Papers

Dismantling MIFARE Classic

RAM: rapid alignment method

Security Flaw in MIFARE Classic