On the Indifferentiability of the Integrated-Key Hash Functions

Most of today\u27s popular hash functions are keyless such that they accept variable-length messages and return fixed-length fingerprints. However, recent separation results reported on several serious inherent weaknesses in these functions, motivating the design of hash functions in the keyed setting. The challenge in this case, however, is that on one hand, it is economically undesirable to abundant the already adopted (keyless) functions in favour of new (keyed) ones, and on the other hand, the process of converting a keyless function to a keyed one is, evidently, non-trivial. A solution to this dilemma is to adopt the integrated-key approach that creates keyed hash functions out of unmodified keyless primitives. In this paper, we adopt several integrated-key constructions and prove that they are indifferentiable from random oracle, showing in details how to develop indifferentiability proofs at the integrated-key setting. The presented indifferentiability proof is generic and can be applied on other hash functions constructed in this setting with sufficiently similar structures to the constructions in this paper

Integrated-Key Cryptographic Hash Functions

Cryptographic hash functions have always played a major role in most cryptographic applications. Traditionally, hash functions were designed in the keyless setting, where a hash function accepts a variable-length message and returns a fixed-length fingerprint. Unfortunately, over the years, significant weaknesses were reported on instances of some popular ``keyless" hash functions. This has motivated the research community to start considering the dedicated-key setting, where a hash function is publicly keyed. In this approach, families of hash functions are constructed such that the individual members are indexed by different publicly-known keys. This has, evidently, also allowed for more rigorous security arguments. However, it turns out that converting an existing keyless hash function into a dedicated-key one is usually non-trivial since the underlying keyless compression function of the keyless hash function does not normally accommodate the extra key input. In this thesis we define and formalise a flexible approach to solve this problem. Hash functions adopting our approach are said to be constructed in the integrated-key setting, where keyless hash functions are seamlessly and transparently transformed into keyed variants by introducing an extra component accompanying the (still keyless) compression function to handle the key input separately outside the compression function. We also propose several integrated-key constructions and prove that they are collision resistant, pre-image resistant, 2nd pre-image resistant, indifferentiable from Random Oracle (RO), indistinguishable from Pseudorandom Functions (PRFs) and Unforgeable when instantiated as Message Authentication Codes (MACs) in the private key setting. We further prove that hash functions constructed in the integrated-key setting are indistinguishable from their variants in the conventional dedicated-key setting, which implies that proofs from the dedicated-key setting can be naturally reduced to the integrated-key setting.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Forensic Tracking and Surveillance

Digital forensics is an emerging field that has uniquely brought together academics, practitioners and law enforcement. Research in this area was inspired by the numerous challenges posed by the increased sophistication of criminal tools. Traditionally, digital forensics has been confined to the extraction of digital evidence from electronic devices. This direct extraction of digital evidence, however, no longer suffices. Indeed, extracting completely raw data without further processing and/or filtering is, in some cases, useless. These problems can be tackled by the so-called ``computational forensics" where the reconstructs evidence are undertaken further processing. One important application of computational forensics is criminal tracking, which we collectively call ``forensic tracking" and is the main subject of this thesis. This thesis adopts an algorithmic approach to investigate the feasibility of conducting forensic tracking in various environments and settings. Unlike conventional tracking, forensic tracking has to be passive such that the target (who is usually a suspect) should not be aware of the tracking process. We begin by adopting pedestrian setting and propose several online (real-time) forensic tracking algorithms to track a single or multiple targets passively. Beside the core tracking algorithms, we also propose other auxiliary algorithms to improve the robustness and resilience of tracking. We then extend the scope and consider vehicular forensic tracking, where we investigate both online and offline tracking. In online vehicular tracking, we also propose algorithms for motion prediction to estimate the near future movement of target vehicles. Offline vehicular tracking, on the other hand, entails the post-hoc extraction and probabilistic reconstruction of vehicular traces, which we adopt Bayesian approach for. Finally, the contributions of the thesis concludes with building an algorithmic solution for multi-modal tracking, which is a mixed environment combining both pedestrian and vehicular settings

Characterisation of Sewage Sludge and Municipal Solid Waste for Use as Cementitious Materials

Volumes of accumulated solid waste materials of sewage sludge (SS) and municipal solid waste (MSW) in Qatar continue to increase annually with a potentially negative impact on the environment. This paper presents an innovative technology for the production of green cement and advanced construction products from SS and MSW. Chemical composition analyses of the solid waste materials indicated the presence of main oxides available in Portland cement, but at lower contents. The three solid waste materials were incinerated and ground to produce consistent powder materials of similar sizes to Portland cement. The physical and chemical characteristics of the solid waste materials were investigated and compared to that of Portland cement. Paste and mortar mixtures were prepared by replacing 25, 50, and 75% of Portland cement with the different solid waste materials. Solid waste materials were found to influence the fresh properties of concrete, mainly water demand and setting time. Increasing the content of solid waste materials resulted in reduced compressive strength at all tested ages. SS gave the best performance within the solid waste materials investigated. Recommendations are made on the effective use of solid waste materials in various construction applications

Can Artificial Noise Boost Further the Secrecy of Dual-hop RIS-aided Networks?

In this paper, we quantify the physical layer security of a dual-hop regenerative relaying-based wireless communication system assisted by reconfigurable intelligent surfaces (RISs). In particular, the setup consists of a source node communicating with a destination node via a regenerative relay. In this setup, a RIS is installed in each hop to increase the source-relay and relay-destination communications reliability, where the RISs' phase shifts are subject to quantization errors. The legitimate transmission is performed under the presence of a malicious eavesdropper attempting to compromise the legitimate transmissions by overhearing the broadcasted signal from the relay. To overcome this problem, we incorporate a jammer to increase the system's secrecy by disrupting the eavesdropper through a broadcasted jamming signal. Leveraging the well-adopted Gamma and Exponential distributions approximations, the system's secrecy level is quantified by deriving approximate and asymptotic expressions of the secrecy intercept probability (IP) metric in terms of the main network parameters. The results show that the secrecy is enhanced significantly by increasing the jamming power and/or the number of reflective elements (REs). In particular, an IP of approximately $10^{-4}$ can be reached with $40$ REs and $10$ dB of jamming power-to-noise ratio even when the legitimate links' average signal-to-noise ratios are $10$-dB less than the eavesdropper's one. We show that cooperative jamming is very helpful in strong eavesdropping scenarios with a fixed number of REs, and the number of quantization bits does not influence the secrecy when exceeding $3$ bits. All the analytical results are endorsed by Monte Carlo simulations

Development and Performance of Cement Bound Materials in Road Pavements

The use of cement bound materials (CBMs) for road construction in Qatar is relatively new. CBM improves the structural capacity and durability of pavement, but considerations should be made to the setting time and strength development in hot arid environment, such as in Qatar. The paper presents a laboratory development and performance characteristics of CBM mixtures, with environmental and economic benefits through the use of local and recycled materials. The developed mixtures showed full compliance with the grading, strength and durability requirements of the Qatar Construction Specifications (QCS, 2014). Site data from Ashghal projects indicated the difficulty of producing consistent strength in practice, with the potential of increased strength and associated risk of reflection cracking in the asphalt overlaying. Recommendations are made to improve the construction practice and specification of cement and other hydraulically bound materials to enhance the service life of pavement and support the government strategy of sustainable construction

Fully Collusion Resistant Trace-and-Revoke Functional Encryption for Arbitrary Identities

Functional Encryption (FE) has been extensively studied in the recent years, mainly focusing on the feasibility of constructing FE for general functionalities, as well as some realizations for restricted functionalities of practical interest, such as inner-product. However, little consideration has been given to the issue of key leakage on FE. The property of FE that allows multiple users to obtain the same functional keys from the holder of the master secret key raises an important problem: if some users leak their keys or collude to create a pirated decoder, how can we identify at least one of those users, given some information about the compromised keys or the pirated decoder? Moreover, how do we disable the decryption capabilities of those users (i.e. traitors)? Two recent works have offered potential solutions to the above traitor scenario. However, the two solutions satisfy weaker notions of security and traceability, can only tolerate bounded collusions (i.e., there is an a priori bound on the number of keys the pirated decoder obtains), or can only handle a polynomially large universe of possible identities. In this paper, we study trace-and-revoke mechanism on FE and provide the first construction of trace-and-revoke FE that supports arbitrary identities, is both fully collusion resistant and fully anonymous. Our construction relies on a generic transformation from revocable predicate functional encryption with broadcast (RPFE with broadcast, which is an extension of revocable predicate encryption with broadcast proposed by Kim and J. Wu at ASIACRYPT\u272020) to trace-and-revoke FE. Since this construction admits a generic construction of trace-and-revoke inner-product FE (IPFE), we instantiate the trace-and-revoke IPFE from the well-studied Learning with Errors (LWE). This is achieved by proposing a new LWE-based attribute-based IPFE (ABIPFE) scheme to instantiate RPFE with broadcast

Expanding Boundaries: Cross-Media Routing for Seamless Underwater and Aerial Communication

The colossal evolution of wireless communication technologies over the past few years has driven increased interest in its integration in a variety of less-explored environments, such as the underwater medium. In this magazine paper, we present a comprehensive discussion on a novel concept of routing protocol known as cross-media routing, incorporating the marine and aerial interfaces. In this regard, we discuss the limitation of single-media routing and advocate the need for cross-media routing along with the current status of research development in this direction. To this end, we also propose a novel cross-media routing protocol known as bubble routing for autonomous marine systems where different sets of AUVs, USVs, and airborne nodes are considered for the routing problem. We evaluate the performance of the proposed routing protocol by using the two key performance metrics, i.e., packet delivery ratio (PDR) and end-to-end delay. Moreover, we delve into the challenges encountered in cross-media routing, unveiling exciting opportunities for future research and innovation. As wireless communication expands its horizons to encompass the underwater and aerial domains, understanding and addressing these challenges will pave the way for enhanced cross-media communication and exploration.Comment: Submitted to IEEE Communications Magazin

A Novel Application of Quantum Speed Limit to String Theory

In this work, we investigate the implications of the concept of quantum speed limit in string field theory. We adopt a novel approach to the problem of time on world-sheet based on Fisher information, and arrive at a minimum time for a particle state to evolve into another particle state. This is done using both the Mandelstam-Tamm bound and the Margolus-Levitin bound. This implies that any interaction has to be smeared over such an interval, and any interaction in the effective quantum field theory has to be non-local. As non-local quantum field theories are known to be finite, it is expected that divergences should be removed from effective quantum field theories due to the quantum speed limit of string theory.Comment: 9 page