Ciphertext only attacks against GSM security

Mobile communications play a center role in today's connected society. The security of the cellular networks that connect billions of people is of the utmost importance. However, even though modern third generation and fourth generation cellular networks (3G and 4G) provide an adequate level of security in the radio interface, most networks and mobile handsets can fall back to the old GSM standard designed almost three decades ago, which has several known security weaknesses. In this work we study the security provided by the family of ciphering algoritms known as A5 that protects the radio access network of GSM, with emphasis on A5/1. We review the existing attacks against A5/1 and existing countermeasures, and show that the existing ciphertext only attacks against algorithm A5/1 [9], adapted to use the most recent Time Memory Data Tradeoff, are realistic threats to fielded GSM networks when attacked by a resourceful attacker which uses current state of the art GPUs and CPUs. We also study the existing Time Memory Data Tradeoff algorithms, extending the best known results for the Perfect Fuzzy Rainbow Tradeoff attack to the multi target case. These results allow the practitioner to calculate the parameters and tradeooff constants that best suit his application. We implemented the algorithms using parallel programming on CUDA GPUs and successfully validated the theoretical estimations. The main contributions of this work can be summarized as follows: Extending the existing best results for the Perfect Fuzzy Rainbow Tradeoff attack in the single target scenario to the multi target scenario. Validating the theoretical calculation of the parameters and tradeoff constants of the Perfect Fuzzy Rainbow tradeoff through implementation for several scenarios. Describing one of the possible procedures for the choice of parameters for the Perfect Fuzzy Rainbow tradeoff. Presenting a new ciphertext only attack against A5/1 using the voice channel in GSM communication. Calculating the details of the ciphertext only attack in [9] and showing that the attack is a realistic threat today using a perfect fuzzy rainbow tradeoff attack and modern GPUs

A Comparison of Time-Memory Trade-Off Attacks on Stream Ciphers

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중복제거 테이블을 이용한 특이점 절충기법과 그의 병렬처리에 대한 분석

학위논문 (박사)-- 서울대학교 대학원 : 수리과학부, 2016. 2. 홍진.In a recent paper, the performances of three major time memory tradeoff algorithms, namely, the classical Hellman tradeoff and the non-perfect table versions of the distinguished point(DP) and the rainbow table tradeoff methods, were analyzed and compared against each other. The analysis was accurate in the sense that the extra costs of resolving false alarms were not ignored, and the performance comparison was fair in the sense that both the online complexity and the pre-computation cost were taken into account and the techniques for optimizing storage size were taken into account. Based on this paper, another recent paper analyzed a DP variant, which treats the non-perfect DP tables in parallel, and compared its performance with those of the previous three tradeoff algorithms. In this thesis, we analyze the performances of three more tradeoff algorithms and compare them with the aforementioned four algorithms. The algorithms newly considered here will be the perfect table versions of the DP, rainbow table, and parallel DP tradeoff methods. The performance of an algorithm cannot be represented by a single numeric value and algorithm preferences will depend on the available resources and various situations faced by the tradeoff algorithm implementer. Hence, we will present the performances of the tradeoff algorithms as curves providing the full range of options made available by the algorithms, so as to allow for the implementers to make their choices. However, our comparisons show that, under typical situations, the perfect table parallel DP tradeoff algorithm is more likely to be preferable over the other DP algorithm variants and that the perfect rainbow table method is superior to the other tradeoff algorithms. On the other hand, yet another recent paper notes that the perfect rainbow table method is widely implemented in practice to process its pre-computation tables in a serial manner, rather than in parallel, as was originally proposed by the algorithm designers. This is because, even though the parallel treatment of the pre-computation tables would be more efficient in theory, the size of tables are too large to be fully loaded into fast main memory in real-world applications such as password recovery and this affects the real-world performances of the algorithms negatively. Following the approach of the paper, we give the optimal physical wall-clock online execution times for the practically used serial perfect rainbow and the perfect table versions of the DP and rainbow tradeoffs that treat their pre-computation tables in parallel. This is done with various realistic password spaces and at various high success rate requirements, under a specific limitation on the size of available storage. Unlike any theoretical approach to the tradeoff algorithms, the physical online execution time includes the time taken for loading the pre-computation tables from disk to fast memory and the time taken by table lookups. We find that, in contrast with the software developers' intuition, the serial perfect rainbow tradeoff algorithm is inferior to the two algorithms that treat their tables in parallel, when their optimal physical online times are compared under reasonable assumptions and settings. Our simplified conclusions are that, for the larger of the two search spaces we dealt with, the parallel version of the perfect rainbow table method gives the shortest wall-clock online time, and that, for the smaller search space, when restricted to the same amount of pre-computation, the perfect parallel DP tradeoff is faster than the other algorithms.Chapter 1 Introduction 1 Chapter 2 Preliminaries 7 2.1 Algorithm Clarification, Terminology, and Notation 7 2.1.1 Four Versions of the DP Tradeoff 8 2.1.2 Non-perfect and Perfect Rainbow Tradeoffs pR, p¯R 19 2.1.3 Perfect Rainbow Tradeoff, Used in Practice s¯R 25 2.1.4 Other Conventions and Comments 27 2.2 Storage Optimization Techniques 28 2.3 Previous Results 29 2.3.1 Analyses of the Original DP and Parallel DP Tradeoffs 30 2.3.2 Analysis of the Non-perfect Rainbow Tradeoff 31 Chapter 3 Perfect Table Tradeoff Algorithms 33 3.1 Analysis of the Perfect DP Tradeoff 33 3.1.1 Online Efficiency 33 3.1.2 Storage Optimization 46 3.1.3 Experiment Results 50 3.2 Analysis of the Perfect Rainbow Tradeoff 56 3.2.1 Online Efficiency 56 3.2.2 Storage Optimization 60 Chapter 4 Perfect Parallel DP Tradeoff 65 4.1 Online Efficiency 65 4.2 Storage Optimization 72 4.3 Experiment Results 75 Chapter 5 Comparisons Focused on Theoretical Complexities 85 5.1 Method of Comparison 86 5.2 Comparison of DP Variants 88 5.3 p¯D vs. Rainbow 92 Chapter 6 Practice-Oriented Comparison 100 6.1 Additional Costs for the p¯D and p¯R Tradeoffs 102 6.2 Analysis of the s¯R Tradeoff 103 6.3 Expressions for the Physical Online Time 104 6.4 How to Minimize the Physical Online Time 106 6.5 Comparisons 107 Chapter 7 Conclusion 116 Bibliography 119 Appendix A Practical System Constants τF, τL, and τH 123 A.1 tF 123 A.2 tL 125 A.3 tH 126 Abstract (in Korean) 129Docto

Towards Green Computing Oriented Security: A Lightweight Postquantum Signature for IoE

[EN] Postquantum cryptography for elevating security against attacks by quantum computers in the Internet of Everything (IoE) is still in its infancy. Most postquantum based cryptosystems have longer keys and signature sizes and require more computations that span several orders of magnitude in energy consumption and computation time, hence the sizes of the keys and signature are considered as another aspect of security by green design. To address these issues, the security solutions should migrate to the advanced and potent methods for protection against quantum attacks and offer energy efficient and faster cryptocomputations. In this context, a novel security framework Lightweight Postquantum ID-based Signature (LPQS) for secure communication in the IoE environment is presented. The proposed LPQS framework incorporates a supersingular isogeny curve to present a digital signature with small key sizes which is quantum-resistant. To reduce the size of the keys, compressed curves are used and the validation of the signature depends on the commutative property of the curves. The unforgeability of LPQS under an adaptively chosen message attack is proved. Security analysis and the experimental validation of LPQS are performed under a realistic software simulation environment to assess its lightweight performance considering embedded nodes. It is evident that the size of keys and the signature of LPQS is smaller than that of existing signature-based postquantum security techniques for IoE. It is robust in the postquantum environment and efficient in terms of energy and computations.This project was funded by the Deanship of Scientific Research (DSR), King Abdulaziz University. Jeddah. under grant No. (DF-457-156-1441).Rani, R.; Kumar, S.; Kaiwartya, O.; Khasawneh, AM.; Lloret, J.; Al-Khasawneh, MA.; Mahmoud, M.... (2021). Towards Green Computing Oriented Security: A Lightweight Postquantum Signature for IoE. Sensors. 21(5):1-20. https://doi.org/10.3390/s2105188312021

A framework for robust control of uncertainty in self-adaptive software connectors

Context and motivations. The desired behavior of a system in ubiquitous environments considers not only its correct functionality, but also the satisfaction of its non-functional properties, i.e., its quality of service. Given the heterogeneity and dynamism characterizing the ubiquitous environments and the need for continuous satisfaction of non-functional properties, self-adaptive solutions appear to be an appropriate approach to achieve interoperability. In this work, self-adaptation is adopted to enable software connectors to adapt the interaction protocols run by the connected components to let them communicate in a timely manner and with the required level of quality. However, this self-adaptation should be dependable, reliable and resilient to be adopted in dynamic, unpredictable environments with different sources of uncertainty. The majority of current approaches for the construction of self-adaptive software ignore the uncertainty underlying non-functional requirement verification and adaptation reasoning. Consequently, these approaches jeopardize system reliability and hinder the adoption of self-adaptive software in areas where dependability is of utmost importance. Objective. The main objective of this research is to properly handle the uncertainties in the non-functional requirement verification and the adaptation reasoning part of the self-adaptive feedback control loop of software connectors. This will enable a robust and runtime efficient adaptation in software connectors and make them reliable for usage in uncertain environments. Method. In the context of this thesis, a framework has been developed with the following functionalities: 1) Robust control of uncertainty in runtime requirement verification. The main activity in runtime verification is fine-tuning of the models that are adopted for runtime reasoning. The proposed stochastic approach is able to update the unknown parameters of the models at runtime even in the presence of incomplete and noisy observations. 2) Robust control of uncertainty in adaptation reasoning. A general methodology based on type-2 fuzzy logic has been introduced for the control of adaptation decision-making that adjusts the configuration of component connectors to the appropriate mode. The methodology enables a systematic development of fuzzy logic controllers that can derive the right mode for connectors even in the presence of measurement inaccuracy and adaptation policy conflicts. Results. The proposed model evolution mechanism is empirically evaluated, showing a significant precision of parameter estimation with an acceptable overhead at runtime. In addition, the fuzzy based controller, generated by the methodology, has been shown to be robust against uncertainties in the input data, efficient in terms of runtime overhead even in large-scale knowledge bases and stable in terms of control theory properties. We also demonstrate the applicability of the developed framework in a real-world domain. Thesis statement. We enable reliable and dependable self-adaptations of component connectors in unreliable environments with imperfect monitoring facilities and conflicting user opinions about adaptation policies by developing a framework which comprises: (a) mechanisms for robust model evolution, (b) a method for adaptation reasoning, and (c) tool support that allows an end-to-end application of the developed techniques in real-world domains