Survey on Security Models Employed in Blockchain Based Applications

Numerous vulnerabilities have a tendency to taint modern real-world web applications, allowing attackers in retrieving sensitive information and exploiting genuine web applications as a platform for malware activities. Moreover, computing techniques are evolved from the large desktop computer systems to the devices like smartphones, smart watches and goggles. This needs to be ensure that these devices improve their usability and will not be utilized for attacking the personal credentilas (such as credit card numbers, transaction passwords, etc.) of the users. Therefore, there is a need of security architecture over the user's credentials so that no unauthorized user can access it. This chapter summarizes various security models and techniques that are being discovered, studied and utilized extensively in order to ensure computer security. It also discusses numerous security principles and presents the models that ensure these security principles. Security models (such as access control models, information flow models, protection ring, etc.) form the basis of various higher level and complex models. Therefore, learning such security models is very much essential for ensuring the security of the computer and cyber world.

The expansion of television streaming services has transformed media consumption, providing unparalleled convenience and access to content. Streamers frequently gather comprehensive user data, encompassing viewing patterns, individual preferences, and financial details. This data can be commercialised via collaborations with external advertisers and data brokers, thereby engendering considerable privacy violations, identity theft, and user confidence deterioration. Generative Adversarial Networks (GANs) present a promising method for improving detection techniques of data transmitted to third parties. GANs can be trained to replicate standard data flow patterns and detect anomalies that suggest unauthorised data sharing. Additionally, GANs can produce synthetic data that simulate authentic user behaviour, thereby aiding in developing resilient real-time detection models. Moreover, GANs can create sophisticated data anonymisation techniques to monitor whether user data has been shared. This paper introduces an innovative, multifaceted security and privacy model utilising GANs and deep learning methodologies to identify and alleviate these threats. It compares the GAN model against traditional Support Vector Machine and Random Forests Classifier models. Our methodology integrates anomaly detection and graphs convolutional networks with generative adversarial networks to detect dubious data-sharing activities. The proposed model illustrates the efficacy of deep learning models, specifically GANs, in identifying unauthorised data-sharing platforms.

This paper presents a comprehensive formal security framework for key derivation functions (KDF). The major security goal for a KDF is to produce cryptographic keys from a private seed value where the derived cryptographic keys are indistinguishable from random binary strings. We form a framework of five security models for KDFs. This consists of four security models that we propose: Known Public Inputs Attack (KPM, KPS), Adaptive Chosen Context Information Attack (CCM) and Adaptive Chosen Public Inputs Attack(CPM); and another security model, previously defined by Krawczyk [6], which we refer to as Adaptive Chosen Context Information Attack(CCS). These security models are simulated using an indistinguisibility game. In addition we prove the relationships between these five security models and analyse KDFs using the framework (in the random oracle model).

There is a need to quantify system properties methodically. Dependability and security models have evolved nearly independently. Therefore, it is crucial to develop a classification of dependability and security models which can meet the requirement of professionals in both fault-tolerant computing and security community. In this paper, we present a new classification of dependability and security models. First we present the classification of threats and mitigations in systems and networks. And then we present several individual model types such as availability, confidentiality, integrity, performance, reliability, survivability, safety and maintainability. Finally we show that each model type can be combined and represented by one of the model representation techniques: combinatorial (such as reliability block diagrams (RBD), reliability graphs, fault trees, attack trees), state-space (continuous time Markov chains, stochastic Petri nets, fluid stochastic Petri nets, etc) and hierarchical (e.g., fault trees in the upper level and Markov chains in the lower level). We show case studies for each individual model types as well as composite model types.

The full deployment of intelligent substations will greatly reduce the difficulty and cost of information sharing, allowing interoperability between intelligent electronic devices (IEDs), which will facilitate high-performance, low-cost automation. This paper builds the security model of intelligent substation information system based on IEC61850. The IED networking scheme is an important foundation and guarantee of its security model. This paper focuses on the two basic networking forms and ring type and hybrid of process bus and station bus. Several types of network redundancy are introduced, and a new substation security model structure network design scheme is given. The results show that the network structure security model has practical significance.

The problem of Byzantine Fault Tolerance (BFT) has received a lot of attention in the last 30 years. Due to the popularity of Proof of Stake (PoS) blockchains in recent years, several BFT protocols have been deployed in the large scale of Internet environment. We analyze several popular BFT protocols such as Capser FFG/CBC-FBC for Ethereum 2.0 and GRANDPA for Polkadot. Our analysis shows that the security models for these BFT protocols are slightly different from the models commonly accepted in the academic literature. For example, we show that, if the adversary has a full control of the message delivery order in the underlying network, then none of the BFT protocols for Ethereum blockchain 2.0 and Polkadot blockchain could achieve liveness even in a synchronized network. Though it is not clear whether a practical adversary could actually control and re-order the underlying message delivery system (at Internet scale) to mount these attacks, it raises an interesting question on security model gaps between academic BFT protocols and deployed BFT protocols in the Internet scale. With these analysis, this article proposes a Casper CBC-FBC style binary BFT protocol and shows its security in the traditional academic security model with complete asynchronous networks. For partial synchronous networks, we propose a multi-value BFT protocol BDLS based on the seminal DLS protocol and show that it is one of the most efficient practical BFT protocols at large scale networks in the traditional academic BFT security model. The implementation of BDLS is available at https://github.com/yonggewang/bdls . Finally, we propose a multi-value BFT protocol XP for complete asynchronous networks and show its security in the traditional academic BFT security model.

In existing systems, information are protected by security models that control the accesses to the information, depending on their security level. In such systems, allowing accesses that were previously denied by diminishing the security level of the information is called downgrading. Controlling this downgrade of sensitive information is an important issue in computer security, as it requires the definition of formal security models able to express contextual authorisations for some information flows. In traditional security models, information downgrading is however most of the time not taken into account and must be managed by external systems. In some recent security models, information downgrading is defined, but for specific security policies, which limits the downgrading controls. In order to be able to express a generic information downgrading control, we present in this article a formalization of the different concepts of downgrading and we propose a model to specify and control downgrade operations. Contrary to existing downgrading models, our model relies on an abstract security policy in order to define downgrading controls that are not restricted to specific scenarios.

We focus on the security issues of decentralized federated learning systems for the core requirements of secure environments and trusted computing for applications such as medical big data, distributed cognitive learning, and autonomous driving. We propose a three-layer security assurance model that aims to ensure secure trusted computing in decentralized networks. Therein, the first-layer security model realizes the authentication of trusted users through blockchain technology to ensure the safe access of legitimate users to the greatest extent; the second-layer security model utilizes the trusted execution environment (TEE) technology to realize the privacy protection and trusted computing of each local user; the last layer of security model adopts a set of detection and location algorithms for defending the internal attackers, in case the first two layers of models fail. Our experimental results show that the proposed three-layer security model can effectively defend against external and internal attacks in the network, thereby promoting secure and trusted computing in distributed federated learning networks.

The Information-Centric Networking (ICN) paradigm is drastically different from traditional host-centric IP networking. As a consequence of the disparity between the two, the security models are also very different. The security model for IP is based on securing the end-to-end communication link between the communicating nodes whereas the ICN security model is based on securing data objects often termed as Object Security. Just like the traditional security model, Object security also poses a challenge of key management. This is especially concerning for ICN as data cached in its encrypted form should be usable by several different users. Attribute-Based Encryption (ABE) alleviates this problem by enabling data to be encrypted under a policy that suits several different types of users. Users with different sets of attributes can potentially decrypt the data hence eliminating the need to encrypt the data separately for each type of user. ABE is a more processing intensive task compared to traditional public key encryption methods hence posing a challenge for resource constrained environments with devices that have low memory and battery power. In this demo we show ABE encryption carried out on a resource constrained sensor platform. Encrypted data is transported over an ICN network and is decrypted only by clients that have the correct set of attributes.

New attacks and security model of the secure flash disk

Cyber-physical systems are at the intersection of digital technology and engineering domains, rendering them high-value targets of sophisticated and well-funded cybersecurity threat actors. Prominent cybersecurity attacks on cyber-physical systems have brought attention to the vulnerability of these systems and the inherent weaknesses of critical infrastructure reliant on them. Security modelling for cyber-physical systems is an important mechanism to systematically identify and assess vulnerabilities, threats and risks throughout system lifecycles, and to ultimately ensure system resilience, safety and reliability. This survey delves into state-of-the-art research on security modelling for cyber-physical systems, encompassing both threat and attack modelling. While these terms are sometimes used interchangeably, they are different concepts. This article elaborates on the differences between threat and attack modelling, examining their implications for cyber-physical system security. We conducted a systematic search that yielded 449 papers, from which 32 were selected and categorised into 3 clusters: those focused on threat modelling methods, attack modelling methods and literature reviews. Specifically, we sought to examine what security modelling methods exist today, and how they address real-world cybersecurity threats and attacker capabilities throughout the lifecycle of cyber-physical systems, which typically span longer durations compared to traditional IT systems. This article also highlights several limitations in existing research, wherein security models adopt simplistic approaches that do not adequately consider the dynamic, multi-layer, multi-path and multi-agent characteristics of real-world cyber-physical attacks.

Three econometric models were built between January and March 2020 to predict the September 3, 2020 General Election in Jamaica. These are the economics and security model (model1), the economics and security model with JLP leader acceptance (model 2), and the economics and security model with PNP leader acceptance (model 3). All three models accurately predicted a win for the Jamaica Labour Party. A Jack-knife resampling was performed for cross validation. These models show how the macro-economy, security concerns and party leader popularity influence election outcomes, with similar findings in the literature. However, there are peculiarities in the Anglophone Caribbean because the Jamaican voters respond to economic and security concerns in different ways than the voters in the global north. For example, increases in the debt to GDP ratio and the homicide rate predicted a JLP win. This work should be replicated in the Caribbean and Latin America using panel data.

It is our great pleasure to welcome you at the 3rd International Conference on Security of Information and Networks -- SIN 2010, organized in technical cooperation with the ACM Special Interest Group on Security, Audit and Control (SIGSAC). The conference, similar to SIN 2009 and SIN 2007, covers practically all aspects of security of information and networks. The SIN 2009 Conference had such sections as "Security Assessment, Policies, Educational Programs", "Security and Integrity Management and Models", "Cryptography, Security and Networks", "Access Control and Security Assurance", and "Attacks, Intrusion Detection". Based on accepted submissions, the following sections are presented at SIN 2010: Security Assessment, Policies, Privacy, and Educational Programs (12 papers);Management and Models of Security and Integrity (9 papers);Cryptography, Security, and Networks (10 papers);Attacks and Intrusion Detection (7 papers). We received 73 submissions of which only a small portion was accepted based on at least two independent reviews. At times three, even four, reviews were secured before a decision could be made. Among all the submissions, 31 were accepted as full papers (42%), 6 as short (8%), and 1 as a position statement (1%). The authors of the submitted papers hail from China, France, Germany, India, Iran, Italy, Japan, North Cyprus, Philippines, Portugal, Russia, Turkey, Ukraine, and USA. The papers of "Security Assessment, Policies, Privacy, and Educational Programs" section consider such topics as security standards and regulations, privacy, anonymity, educational issues, and digital forensics. "Management and Models of Security and Integrity" section papers consider various security management policies, models and architectures. "Cryptography, Security, and Networks" section features papers on cryptographic algorithms and protocols, as well as networks security. And finally, "Attacks and Intrusion Detection" section combines the papers discussing the detection and prevention of intrusions. SIN 2010 Conference gives researchers and practitioners a unique opportunity to share their perspectives with others interested in the various aspects of security of information and networks. We hope that these proceedings will serve as a valuable reference for security researchers and developers.

The concept of policy-based cryptography is a promising paradigm for trust establishment and authorization in largescale open environments like the Internet and Mobile Networks. It aims at providing a framework for performing cryptographic operations with respect to policies formalized as monotone Boolean expressions written in standard normal forms. A policy involves conjunctions and disjunctions of conditions where each condition is fulfilled by a digital credential representing the signature of a specific credential issuer on a set of statements about a certain entity. Therefore, an entity fulfills a policy if any only if it has been issued a set of credentials fulfilling the combination of conditions specified by the policy.In this work, we focus on policy-based encryption schemes which allow to encrypt a message according to a policy so that only entities fulfilling the policy are able to decrypt the message. More generally, policy-based encryption belongs to an emerging family of encryption schemes sharing the ability to integrate encryption with access control structures. This ability is mainly enabled by bilinear pairings over elliptic curves and allows for several interesting applications in different contexts.A policy-based encryption scheme has to fulfill two primary requirements: on one hand, provable security under well defined attack models. On the other hand, efficiency, especially when dealing with the conjunctions and disjunctions of credential-based conditions.The contributions of our research work are twofold:1. The standard acceptable notion of security for public-key encryption schemes is indistinguishability against chosen ciphertext attacks. Hence, it is natural to require that a policy-based encryption scheme also satisfies this strong notion of security. However, the definition of this security notion must be adapted to the policy-based setting. Our first contribution is the definition of policy-oriented security model for policy-based encryption schemes as well as the development of an efficient policy-based encryption scheme that is provably secure under our security model in the random oracle model.2. Policy-based encryption schemes may suffer from the key-escrow property i.e. in addition to the legitimate holder of the credentials fulfilling the encryption policy, any collusion of credential issuers who are able to issue a set of credentials fulfilling the policy can decrypt the message. Our second contribution is to address this issue through the notion of policy-based public-key encryption. The latter allows encrypting a message not only with respect to a policy but also according to a public-key so that only an entity fulfilling the policy and having access to the corresponding private-key is able to decrypt the message. We developed a policy-based public-key encryption scheme from bilinear pairings and proved its security under the corresponding security model. Our proposal improves related work in terms of both security and efficiency.

Formal verification of information flow security with dynamic policies of security-critical systems is a grand challenge. This paper presents the first effort to formally specify and verify a capability-based system model with dynamic information flow policies. We build a generic security model with dynamic security policies. In the security model, we define a set of information flow security properties and provide an inference framework for them. Based on the security model, we propose a system model for capability-based secure systems. The system model specifies critical events including system initialization, inter-domain communication, and capability management. We prove information flow security of the capability-based model by an unwinding theorem. Formal specification and security proof are carried out in the Isabelle/HOL theorem prover and could be applied to formally develop and verify the security of capability-based secure systems, such as separation kernels and secure hypervisors. To our knowledge, this is the first machine-checked proof of capability-based information security with dynamic policies.