09031 Abstracts Collection -- Symmetric Cryptography

From 11.01.09 to 16.01.09, the Seminar 09031 in ``Symmetric Cryptography \u27\u27 was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Criptografía ligera en internet de las cosas para la industria

La Criptografía Ligera o Liviana (Lightweight Cryptography) es uno de los temas de actualidad de la Criptología. Una gran variedad de algoritmos “livianos” han sido diseñados para garantizar Confidencialidad, Autenticidad e Integridad de los datos en dispositivos de lo que se ha dado en llamar Internet de las Cosas (IoT por sus siglas en inglés). Algunos de ellos surgen del ámbito académico y se aplican en la Industria; otros son propietarios, desarrollados por las empresas para satisfacer sus requerimientos de seguridad. En este trabajo se presenta el estado del arte de algunos de tales algoritmos empleados en diferentes dispositivos IoT. Se describen brevemente sus características criptológicas generales y se muestran los diferentes ataques a los que fueron sometidos. Finalmente se enumeran algunas de las tendencias para el diseño e implementación de dichas primitivas.VIII Workshop Seguridad informática.Red de Universidades con Carreras en Informátic

Criptografía ligera en internet de las cosas para la industria

La Criptografía Ligera o Liviana (Lightweight Cryptography) es uno de los temas de actualidad de la Criptología. Una gran variedad de algoritmos “livianos” han sido diseñados para garantizar Confidencialidad, Autenticidad e Integridad de los datos en dispositivos de lo que se ha dado en llamar Internet de las Cosas (IoT por sus siglas en inglés). Algunos de ellos surgen del ámbito académico y se aplican en la Industria; otros son propietarios, desarrollados por las empresas para satisfacer sus requerimientos de seguridad. En este trabajo se presenta el estado del arte de algunos de tales algoritmos empleados en diferentes dispositivos IoT. Se describen brevemente sus características criptológicas generales y se muestran los diferentes ataques a los que fueron sometidos. Finalmente se enumeran algunas de las tendencias para el diseño e implementación de dichas primitivas.VIII Workshop Seguridad informática.Red de Universidades con Carreras en Informátic

Dismantling the AUT64 Automotive Cipher

AUT64 is a 64-bit automotive block cipher with a 120-bit secret key used in a number of security sensitive applications such as vehicle immobilization and remote keyless entry systems. In this paper, we present for the first time full details of AUT64 including a complete specification and analysis of the block cipher, the associated authentication protocol, and its implementation in a widely-used vehicle immobiliser system that we have reverse engineered. Secondly, we reveal a number of cryptographic weaknesses in the block cipher design. Finally, we study the concrete use of AUT64 in a real immobiliser system, and pinpoint severe weaknesses in the key diversification scheme employed by the vehicle manufacturer. We present two key-recovery attacks based on the cryptographic weaknesses that, combined with the implementation flaws, break both the 8 and 24 round configurations of AUT64. Our attack on eight rounds requires only 512 plaintext-ciphertext pairs and, in the worst case, just 237.3 offline encryptions. In most cases, the attack can be executed within milliseconds on a standard laptop. Our attack on 24 rounds requires 2 plaintext-ciphertext pairs and 248.3 encryptions to recover the 120-bit secret key in the worst case. We have strong indications that a large part of the key is kept constant across vehicles, which would enable an attack using a single communication with the transponder and negligible offline computation

Where's Crypto?: Automated Identification and Classification of Proprietary Cryptographic Primitives in Binary Code

The continuing use of proprietary cryptography in embedded systems across many industry verticals, from physical access control systems and telecommunications to machine-to-machine authentication, presents a significant obstacle to black-box security-evaluation efforts. In-depth security analysis requires locating and classifying the algorithm in often very large binary images, thus rendering manual inspection, even when aided by heuristics, time consuming. In this paper, we present a novel approach to automate the identification and classification of (proprietary) cryptographic primitives within binary code. Our approach is based on Data Flow Graph (DFG) isomorphism, previously proposed by Lestringant et al. Unfortunately, their DFG isomorphism approach is limited to known primitives only, and relies on heuristics for selecting code fragments for analysis. By combining the said approach with symbolic execution, we overcome all limitations of their work, and are able to extend the analysis into the domain of unknown, proprietary cryptographic primitives. To demonstrate that our proposal is practical, we develop various signatures, each targeted at a distinct class of cryptographic primitives, and present experimental evaluations for each of them on a set of binaries, both publicly available (and thus providing reproducible results), and proprietary ones. Lastly, we provide a free and open-source implementation of our approach, called Where's Crypto?, in the form of a plug-in for the popular IDA disassembler.Comment: A proof-of-concept implementation can be found at https://github.com/wheres-crypto/wheres-crypt

State of the Art in Lightweight Symmetric Cryptography

Lightweight cryptography has been one of the ``hot topics'' in symmetric cryptography in the recent years. A huge number of lightweight algorithms have been published, standardized and/or used in commercial products. In this paper, we discuss the different implementation constraints that a ``lightweight'' algorithm is usually designed to satisfy. We also present an extensive survey of all lightweight symmetric primitives we are aware of. It covers designs from the academic community, from government agencies and proprietary algorithms which were reverse-engineered or leaked. Relevant national (\nist{}...) and international (\textsc{iso/iec}...) standards are listed. We then discuss some trends we identified in the design of lightweight algorithms, namely the designers' preference for \arx{}-based and bitsliced-S-Box-based designs and simple key schedules. Finally, we argue that lightweight cryptography is too large a field and that it should be split into two related but distinct areas: \emph{ultra-lightweight} and \emph{IoT} cryptography. The former deals only with the smallest of devices for which a lower security level may be justified by the very harsh design constraints. The latter corresponds to low-power embedded processors for which the \aes{} and modern hash function are costly but which have to provide a high level security due to their greater connectivity

State of the Art in Lightweight Symmetric Cryptography

Lightweight cryptography has been one of the hot topics in symmetric cryptography in the recent years. A huge number of lightweight algorithms have been published, standardized and/or used in commercial products. In this paper, we discuss the different implementation constraints that a lightweight algorithm is usually designed to satisfy in both the software and the hardware case. We also present an extensive survey of all lightweight symmetric primitives we are aware of. It covers designs from the academic community, from government agencies and proprietary algorithms which were reverse-engineered or leaked. Relevant national (NIST...) and international (ISO/IEC...) standards are listed. We identified several trends in the design of lightweight algorithms, such as the designers\u27 preference for ARX-based and bitsliced-S-Box-based designs or simpler key schedules. We also discuss more general trade-offs facing the authors of such algorithms and suggest a clearer distinction between two subsets of lightweight cryptography. The first, ultra-lightweight cryptography, deals with primitives fulfilling a unique purpose while satisfying specific and narrow constraints. The second is ubiquitous cryptography and it encompasses more versatile algorithms both in terms of functionality and in terms of implementation trade-offs

Linear and Differential Cryptanalysis

Import 11/07/2012Tématem této diplomové práce je lineární a diferenciální kryptoanalýza. Práce však obecně pojednává také o kryptologii a kryptoanalýze jako takové. Jsou zde podrobně probrány blokové šifrovací algoritmy DES, AES (symetrické šifrování) a jejich zjednodušené verze, dále jsou zde popsány různé metody kryptoanalýzy, druhy útoků na jednotlivé typy šifrování, a samozřejmě jsou také rozebrány výhody a nevýhody blokových šifrovacích algoritmů. Cílem diplomové práce pak zejména bylo podrobně prozkoumat obor lineární a diferenciální kryptoanalýzy, a navrhnout aplikaci, která by demonstrovala a názorně ukázala jednotlivé metody kryptoanalýzy v praxi, tedy jak je možné realizovat dané druhy útoků či metody kryptoanalýzy.The main topic of this thesis is the Linear and Differential Cryptanalysis. However, work also deals in general with the cryptology and the cryptanalysis as such. In detail are discussed the block encryption algorithms DES, AES (with symmetric encryption) and their simplified versions, then there are described different methods of the cryptanalysis, types of attacks on different types of encryptions, and of course the advantages and disadvantages of the block encryption algorithms are also discussed. The aim of this thesis was to examine particular field of the linear and differential cryptanalysis in detail, and then design and implement an application for demonstration and illustration of various methods of cryptanalysis in practice.460 - Katedra informatikydobř