Sharif Digital Repository

The increasing integration of modern network infrastructure into industrial control systems elevates the need for robust cyber intrusion detection for industrial protocols. Unsupervised, anomaly-based machine learning methods are particularly well-suited for this task, as they can identify novel attacks by learning a model of normal network behavior without requiring access to scarce attack samples. While techniques like autoencoders, which use reconstruction error to flag deviations, can be effective, their application is often hindered by practical challenges, such as regulatory constraints and the large volumes of data that prohibit the centralized collection required for training.... 

With the continuous development of networks and communication technologies, security evaluation of cryptographic primitives, including block ciphers, which serve as the foundation for securing numerous communication protocols in these networks and technologies, has become more crucial than ever before. Inadequate security at block ciphers endures a risk to the overall security architecture of a system. Therefore, significant attention has been devoted to the development of methods for breaking and evaluating the security of block ciphers, known as cryptanalysis. In this thesis, we investigate division property-based integral cryptanalysis, which is one of the latest distinguisher-based... 

With the spread of threats against industrial control systems, preserving the security of these systems faces serious challenges. On the other hand, with the increase of communication between industrial control networks and external communication networks, the entry points of these networks have also increased and this exposes them to IP network threats. Beside that, traditional attacks on these systems, which generally occur by infiltrating the internal network, are also constantly changing and becoming more complex. These attacks mainly have a phase of hiding the attack from the monitoring systems, which eliminates the possibility of identifying the attacker's operations to a great extent... 

With the growing prevalence of cyber-attacks and the increasing complexity of communication networks, network security has become one of the most critical challenges in the field of information technology. Among the most effective tools for securing networks are Intrusion Detection Systems (IDS), which are capable of identifying abnormal behaviors and network-based attacks. However, many IDSs are vulnerable to adversarial attacks—carefully crafted manipulations intended to mislead their detection mechanisms. This thesis proposes an enhanced adversarial attack framework that leverages Generative Adversarial Networks (GANs), attention mechanisms, and active learning to generate deceptive... 

In an age where Android malware is quickly multiplying and obfuscation is becoming increasingly advanced, safety in the Android ecosystem has emerged as one of the biggest problems in current information technology. Reflection can be considered one of the most robust and harmful obfuscation strategies, as it alters the call graph as well as hides important execution paths. Most malware detection frameworks, such as MsDroid, are susceptible to this type of obfuscation, allowing significant decrease in abilities to accurately identify malicious behavioral patterns. In this research, we introduce a new architecture to improve malware detection against reflection-based obfuscation. The... 

The meaning and the nature of space and it’s essential properties seems to be one of the oldest problems which has been continuing to occupy human’s mind during centuries. It can be counted as a common ground between philosophy, mathematics, physics and even art. However this thesis concentrates on the philosophical and mathematical attitudes, neglecting the other aspects of the issue. Prima facie, it appears that the concept of space is essentially mingled with geometry, the science which seems to investigate the essentials of space. Taking it for granted, Kant regarded space, and so Euclidean geometry which dominates it, as an indispensible and necessary structure of the human’s mind.... 

Using interpolation and starting with Bernoulli numbers, posed by Leopold and Kubota, the aspect of adic function was constructed as adic analogues of the Dirichlet functions.Studing Galois module theory of ideal class group and his favorite structure extensions and modules related to them,Iwasawa found a new method for constructing adic functions by using Stickelberger’s elements.These results wich established by Iwasawa are known as Iwasawa Theory and they have many application in Algebriac Number Theory. Iwasawa’s most remarkable disconvry is the facet that at least in some important cases, there is a similar deep algebraic and analytic dichotomy in arithmetic of extensions. A... 

The density-based clustering algorithm, DBSCAN, is widely recognized for its unique ability to identify arbitrarily shaped clusters and handle noise. However, with the exponential growth of data in modern applications, the algorithm's high computational complexity has become a significant bottleneck, limiting its scalability for large datasets. This research addresses this challenge by introducing and evaluating a novel hybrid clustering algorithm, named HB-DBSCAN. The proposed method is based on a "divide and conquer" strategy, with its core innovation lying in a fast and non-iterative partitioning process driven by one-dimensional histogram analysis. In this algorithm, the natural... 

Hardware Trojans have emerged as a major concern for integrated circuits in recent years. As a result, detecting Trojans has become an important issue in critical applications, such as finance and health. In this work, a trusted platform for detecting Trojans in FPGA bitstreams is presented. The proposed methodology takes advantage of increased Trojan activation, caused by transition aware partitioning of the circuit, while it benefits partial reconfiguration feature of FPGAs to reduce area overhead. Simulation results, performed for the transition probability thresholds of 〖10〗^(-4) and 〖2×10〗^(-5), show that this method increases the ratio of the number of transitions in the Trojan... 

In recent years, in addition to traditional cryptographic blocks, a hardware blocks in this work namely PUF, has been used mostly for chip ID generation, authentication and so on. In this work we study recent proposed PUFs and their implementations on FPGA, and the measurement of quality metrics on them. Some of most important characteristics of PUFs are unpredictability, reliability, number of challenge response pairs and area. According to experiments that have been performed in this study and also according to previous work, one high-quality PUF in term of uniqueness and reliability is Ring Oscillator PUF. However, the disadvantage of this PUF is small number of challenge and response... 

Due to the expansion of digital system threats, trusted computation with a new approach for countering such threats has emerged. This approach is based on using a hardware module for implementing a trusted platform (TPM). TPM includes a chipset and the trusted systems core. Nowadays many of mobile computers do include this technology. This hardware creates trust using a trust chain and expanding this trust to other parts of the system. The starting point in this chain is the computer BIOS. BIOS is the first code that the system usually executes. One of the most powerful recent attacks on computer systems is to infect the BIOS and other firmware. One of such complicated attacks is the rootkit... 

Public key encryption (PKE) cryptography plays a big role in securing communication channels of internet. The security of every PKE scheme is usually based on a hard problem that has no polynomial time solution using any computational structure. However, widely used classic PKE schemes such as RSA or ECC, are based on hard problems that have polynomial solutions using a quantum computer. Therefore, such PKE schemes will not be secure in post-quantum era. Among quantum-resistant schemes, lattice-based cryptography and especially learning with errors (LWE) problem have gained high attention due to their low computational complexity. In this thesis, different LWE-based cryptosystems are... 

Recently, Convolutional neural networks (CNNs) are widely used in many artificial intelligence applications such as image processing, speech processing and robotics. The neural networks superior accuracy comes at the cost of high computational complexity. Recent studies show that these operations can be performed in parallel. Therefore, as graphic processing units (GPUs) offer the best performance in terms of computational power and throughput, they are widely used to implement and accelerate neural networks. Nevertheless, the high price and power consumption of these processors have resulted in drawing more attraction towards Field-Programmable Arrays (FPGAs). In order to improve resource... 

Cloud computing has a significant role in expanding applications of the Internet of Things (IoT). Currently, applications such as virtual reality and augmented reality require low latency, which is not achievable using traditional cloud computing in some scenarios. Edge computing is a new approach in IoT, which solves some of the limitations of the cloud computing by extending and developing its operations. Reducing response time and network traffic are some of the most important achievements of edge computing. Despite of its numerous advantages over cloud computing, edge computing faces serious challenges such as virtualization, implementation infrastructure, resource allocation and task... 

Due to the widespread growth in the use of IoT devices, authors consider these devices as an attractive target platform. Several approaches have been proposed to defend IoT devices against various attacks. However, most of them suffer from some shortcomings such as being computationally expensive, not being general, or not being robust enough.Due to the attacks such as firmware modification and the existence of computational limitations, the use of local approaches is inefficient. Another approach is to use remote attestation techniques, which are divided into two categories, static and dynamic. However, static detection techniques are vulnerable to runtime attacks. Furthermore, existing... 

A distributed ledger is a method of digital data storage and sharing in different places, and the blockchain technology is a way of implementing a distributed ledger. This technology has been employed in many of the cryptocurrencies like Ethereum to store transactions. In addition to storing transactions, Ethereum deploys scripts called smart contracts that are automatically executable. These scripts execute transparently and without preserving the privacy of participants. On the other hand, confidentiality and privacy are among the important components in data, network, and system security. Models such as Hawk and Enigma have been presented to obtain privacy-preserving in smart contracts;... 

Nowadays, with the advancement of internet of things, The number of nodes within the network has increased and there is huge traffic in these networks despite the small volume of data sent and received each node. The current architecture of the Internet network does not have the functionality required for Internet of things, as a result of designing a new architecture for Internet - based Internet of things. Content - based network is a new architecture introduced to the Internet, and its purpose is to change the network from host-centric to content-centric. One of the features of content-based networks is the use of in network caching that helps increase productivity and reduce the traffic... 

Today Internet of Things (IoT) applications are growing rapidly around us and alongside this trend, the topics of security and trust in this field are getting more serious. A big part of this field is composed of embedded systems. Remote attestation is a prominent security option in regards of attesting to the integrity of these type of systems and consequently establishing trust remotely. Remote attestation has been an active field of research to attest different type of systems against various types of threats. A noteworthy security hardware, enabling this type of process, is the Trusted Platform Module (TPM). Incorporating this chip in traditional personal computers for security purposes...