A Real-time Inversion Attack on the GMR-2 Cipher Used in the Satellite Phones

The GMR-2 cipher is a type of stream cipher currently being used in some Inmarsat satellite phones. It has been proven that such a cipher can be cracked using only one single-frame (15 bytes) known keystream but with a moderate executing times. In this paper, we present a new thorough security analysis of the GMR-2 cipher. We first study the inverse properties of the cipher\u27s components to reveal a bad one-way character of the cipher. By then introducing a new concept called ``valid key chain according to the cipher\u27s key schedule, we propose an unprecedented real-time inversion attack using a single-frame keystream. This attack comprises three phases: (1) table generation; (2) dynamic table look-up, filtration and combination; and (3) verification. Our analysis shows that, using the proposed attack, the size of the exhaustive search space for the 64-bit encryption key can be reduced to approximately $2^{13}$ when a single-frame keystream is available. Compared with previous known attacks, this inversion attack is much more efficient. Finally, the proposed attack is carried out on a 3.3-GHz PC, and the experimental results thus obtained demonstrate that the 64-bit encryption-key could be recovered in approximately 0.02 s on average

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

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

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

A review of cyber threats and defence approaches in emergency management

Emergency planners, first responders and relief workers increasingly rely on computational and communication systems that support all aspects of emergency management, from mitigation and preparedness to response and recovery. Failure of these systems, whether accidental or because of malicious action, can have severe implications for emergency management. Accidental failures have been extensively documented in the past and significant effort has been put into the development and introduction of more resilient technologies. At the same time researchers have been raising concerns about the potential of cyber attacks to cause physical disasters or to maximise the impact of one by intentionally impeding the work of the emergency services. Here, we provide a review of current research on the cyber threats to communication, sensing, information management and vehicular technologies used in emergency management. We emphasise on open issues for research, which are the cyber threats that have the potential to affect emergency management severely and for which solutions have not yet been proposed in the literature

Cryptanalysis, Reverse-Engineering and Design of Symmetric Cryptographic Algorithms

In this thesis, I present the research I did with my co-authors on several aspects of symmetric cryptography from May 2013 to December 2016, that is, when I was a PhD student at the university of Luxembourg under the supervision of Alex Biryukov. My research has spanned three different areas of symmetric cryptography. In Part I of this thesis, I present my work on lightweight cryptography. This field of study investigates the cryptographic algorithms that are suitable for very constrained devices with little computing power such as RFID tags and small embedded processors such as those used in sensor networks. Many such algorithms have been proposed recently, as evidenced by the survey I co-authored on this topic. I present this survey along with attacks against three of those algorithms, namely GLUON, PRINCE and TWINE. I also introduce a new lightweight block cipher called SPARX which was designed using a new method to justify its security: the Long Trail Strategy. Part II is devoted to S-Box reverse-engineering, a field of study investigating the methods recovering the hidden structure or the design criteria used to build an S-Box. I co-invented several such methods: a statistical analysis of the differential and linear properties which was applied successfully to the S-Box of the NSA block cipher Skipjack, a structural attack against Feistel networks called the yoyo game and the TU-decomposition. This last technique allowed us to decompose the S-Box of the last Russian standard block cipher and hash function as well as the only known solution to the APN problem, a long-standing open question in mathematics. Finally, Part III presents a unifying view of several fields of symmetric cryptography by interpreting them as purposefully hard. Indeed, several cryptographic algorithms are designed so as to maximize the code size, RAM consumption or time taken by their implementations. By providing a unique framework describing all such design goals, we could design modes of operations for building any symmetric primitive with any form of hardness by combining secure cryptographic building blocks with simple functions with the desired form of hardness called plugs. Alex Biryukov and I also showed that it is possible to build plugs with an asymmetric hardness whereby the knowledge of a secret key allows the privileged user to bypass the hardness of the primitive

Analysis and Design of Authentication and Encryption Algorithms for Secure Cloud Systems

Along with the fast growth of networks and mobile devices, cloud computing has become one of the most attractive and effective technologies and business solutions nowadays. Increasing numbers of organizations and customers are migrating their businesses and data to the cloud due to the flexibility and cost-efficiency of cloud systems. Preventing unauthorized access of sensitive data in the cloud has been one of the biggest challenges when designing a secure cloud system, and it strongly relies on the chosen authentication and encryption algorithms for providing authenticity and confidentiality, respectively. This thesis investigates various aspects of authentication and encryption algorithms for securing cloud systems, including authenticated encryption modes of operation, block ciphers, password hashing algorithms, and password-less/two-factor authentication mechanisms. Improving Authenticated Encryption Modes. The Galois/Counter Mode (GCM) is an authenticated encryption mode of operation for block ciphers. It has been widely adopted by many network standards and protocols that protect the security of cloud communications, such as TLS v1.2, IEEE 802.1AE and IPsec. Iwata et al. recently found a flaw in GCM's original proofs for non-96-bit nonce cases, and then presented new security bounds for GCM. The new bounds imply that the success probabilities of adversaries for attacking GCM are much larger than the originally expected ones. We propose a simple change to repair GCM. When applied, it will improve the security bounds by a factor of about $2^{20}$ while maintaining most of the original proofs. Analyzing Polynomial-Based Message Authentication Codes. We investigate attacks on polynomial-based message authentication code (MAC) schemes including the one adopted in GCM. We demonstrate that constructing successful forgeries of these MAC schemes does not necessarily require hash collisions. This discovery removes certain restrictions in the attacks previously proposed by Procter and Cid. Moreover, utilizing a special design of GCM for processing non-96-bit nonces, we turn these forgery attacks into birthday attacks, which will significantly increase their success probabilities. Therefore, by considering the birthday attacks and the security proof flaw found by Iwata et al., cloud system designers should avoid using GCM with non-96-bit nonces if they do not revise the design of GCM. Analyzing Block Ciphers. We propose a new framework for analyzing symmetric-key ciphers by guessing intermediate states to divide ciphers into small components. This framework is suitable for lightweight ciphers with simple key schedules and block sizes smaller than key lengths. Using this framework, we design new attacks on the block cipher family KATAN. These attacks can recover the master keys of 175-round KATAN32, 130-round KATAN48 and 112-round KATAN64 faster than exhaustive search, and thus reach many more rounds than the existing attacks. We also provide new attacks on 115-round KATAN32 and 100-round KATAN48 in order to demonstrate that this new kind of attack can be more time-efficient and memory-efficient than the existing ones. Designing Password Hashing Algorithms. Securely storing passwords and deriving cryptographic keys from passwords are also crucial for most secure cloud system designs. However, choices of well-studied password hashing algorithms are extremely limited, as their security requirements and design principles are different from common cryptographic primitives. We propose two practical password hashing algorithms, Pleco and Plectron. They are built upon well-understood cryptographic algorithms, and combine the advantages of symmetric-key and asymmetric-key primitives. By employing the Rabin cryptosystem, we prove that the one-wayness of Pleco is at least as strong as the hard problem of integer factorization. In addition, both password hashing algorithms are designed to be sequential memory-hard, in order to thwart large-scale password searching using parallel hardware, such as GPUs, FPGAs, and ASICs. Designing Password-less/Two-Factor Authentication Mechanisms. Motivated by a number of recent industry initiatives, we propose Loxin, an innovative solution for password-less authentication for cloud systems and web applications. Loxin aims to improve on passwords with respect to both usability and security. It utilizes push message services for mobile devices to initiate authentication transactions based on asymmetric-key cryptography, and enables users to access multiple services by using pre-owned identities, such as email addresses. In particular, the Loxin server cannot generate users' authentication credentials, thereby eliminating the potential risk of credential leakage if the Loxin server gets compromised. Furthermore, Loxin is fully compatible with existing password-based authentication systems, and thus can serve as a two-factor authentication mechanism

Electromagnetic Side-Channel Resilience against Lightweight Cryptography

Side-channel attacks are an unpredictable risk factor in cryptography. Therefore, observations of leakages through physical parameters, i.e., power and electromagnetic (EM) radiation, etc., of digital devices are essential to minimise vulnerabilities associated with cryptographic functions. Compared to costs in the past, performing side-channel attacks using inexpensive test equipment is becoming a reality. Internet-of-Things (IoT) devices are resource-constrained, and lightweight cryptography is a novel approach in progress towards IoT security. Thus, it would provide sufficient data and privacy protection in such a constrained ecosystem. Therefore, cryptanalysis of physical leakages regarding these emerging ciphers is crucial. EM side-channel attacks seem to cause a significant impact on digital forensics nowadays. Within existing literature, power analysis seems to have considerable attention in research whereas other phenomena, such as EM, should continue to be appropriately evaluated in playing a role in forensic analysis.The emphasis of this thesis is on lightweight cryptanalysis. The preliminary investigations showed no Correlation EManalysis (CEMA) of PRESENT lightweight algorithm. The PRESENT is a block cipher that promises to be adequate for IoT devices, and is expected to be used commercially in the future. In an effort to fill in this research gap, this work examines the capabilities of a correlation EM side-channel attack against the PRESENT. For that, Substitution box (S-box) of the PRESENT was targeted for its 1st round with the use of a minimum number of EM waveforms compared to other work in literature, which was 256. The attack indicates the possibility of retrieving 8 bytes of the secret key out of 10 bytes. The experimental process started from a Simple EMA (SEMA) and gradually enhanced up to a CEMA. The thesis presents the methodology of the attack modelling and the observations followed by a critical analysis. Also, a technical review of the IoT technology and a comprehensive literature review on lightweight cryptology are included

Lightweight cryptography on ultra-constrained RFID devices

Devices of extremely small computational power like RFID tags are used in practice to a rapidly growing extent, a trend commonly referred to as ubiquitous computing. Despite their severely constrained resources, the security burden which these devices have to carry is often enormous, as their fields of application range from everyday access control to human-implantable chips providing sensitive medical information about a person. Unfortunately, established cryptographic primitives such as AES are way to 'heavy' (e.g., in terms of circuit size or power consumption) to be used in corresponding RFID systems, calling for new solutions and thus initiating the research area of lightweight cryptography. In this thesis, we focus on the currently most restricted form of such devices and will refer to them as ultra-constrained RFIDs. To fill this notion with life and in order to create a profound basis for our subsequent cryptographic development, we start this work by providing a comprehensive summary of conditions that should be met by lightweight cryptographic schemes targeting ultra-constrained RFID devices. Building on these insights, we then turn towards the two main topics of this thesis: lightweight authentication and lightweight stream ciphers. To this end, we first provide a general introduction to the broad field of authentication and study existing (allegedly) lightweight approaches. Drawing on this, with the (n,k,L)^-protocol, we suggest our own lightweight authentication scheme and, on the basis of corresponding hardware implementations for FPGAs and ASICs, demonstrate its suitability for ultra-constrained RFIDs. Subsequently, we leave the path of searching for dedicated authentication protocols and turn towards stream cipher design, where we first revisit some prominent classical examples and, in particular, analyze their state initialization algorithms. Following this, we investigate the rather young area of small-state stream ciphers, which try to overcome the limit imposed by time-memory-data tradeoff (TMD-TO) attacks on the security of classical stream ciphers. Here, we present some new attacks, but also corresponding design ideas how to counter these. Paving the way for our own small-state stream cipher, we then propose and analyze the LIZARD-construction, which combines the explicit use of packet mode with a new type of state initialization algorithm. For corresponding keystream generator-based designs of inner state length n, we prove a tight (2n/3)-bound on the security against TMD-TO key recovery attacks. Building on these theoretical results, we finally present LIZARD, our new lightweight stream cipher for ultra-constrained RFIDs. Its hardware efficiency and security result from combining a Grain-like design with the LIZARD-construction. Most notably, besides lower area requirements, the estimated power consumption of LIZARD is also about 16 percent below that of Grain v1, making it particularly suitable for passive RFID tags, which obtain their energy exclusively through an electromagnetic field radiated by the reading device. The thesis is concluded by an extensive 'Future Research Directions' chapter, introducing various new ideas and thus showing that the search for lightweight cryptographic solutions is far from being completed