Broadcast Authentication for Wireless Sensor Networks Using Nested Hashing and the Chinese Remainder Theorem

Secure broadcasting is an essential feature for critical operations in wireless sensor network (WSNs). However, due to the limited resources of sensor networks, verifying the authenticity for broadcasted messages is a very difficult issue. μTESLA is a broadcast authentication protocol, which uses network-wide loose time synchronization with one-way hashed keys to provide the authenticity verification. However, it suffers from several flaws considering the delay tolerance, and the chain length restriction. In this paper, we propose a protocol which provides broadcast authentication for wireless sensor networks. This protocol uses a nested hash chain of two different hash functions and the Chinese Remainder Theorem (CRT). The two different nested hash functions are employed for the seed updating and the key generation. Each sensor node is challenged independently with a common broadcasting message using the CRT. Our algorithm provides forward and non-restricted key generation, and in addition, no time synchronization is required. Furthermore, receivers can instantly authenticate packets in real time. Moreover, the comprehensive analysis shows that this scheme is efficient and practical, and can achieve better performance than the μTESLA system

An Improved TESLA Protocol Based on Queuing Theory and Benaloh-Leichter SSS in WSNs

Broadcast authentication is a fundamental security technology in wireless sensor networks (ab. WSNs). As an authentication protocol, the most widely used in WSN, TESLA protocol, its publication of key is based on a fixed time interval, which may lead to unsatisfactory performance under the unstable network traffic environment. Furthermore, the frequent network communication will cause the delay authentication for some broadcast packets while the infrequent one will increase the overhead of key computation. To solve these problems, this paper improves the traditional TESLA by determining the publication of broadcast key based on the network data flow rather than the fixed time interval. Meanwhile, aiming at the finite length of hash chain and the problem of exhaustion, a self-renewal hash chain based on Benaloh-Leichter secret sharing scheme (SRHC-BL SSS) is designed, which can prolong the lifetime of network. Moreover, by introducing the queue theory model, we demonstrate that our scheme has much lower key consumption than TESLA through simulation evaluations. Finally, we analyze and prove the security and efficiency of the proposed self-renewal hash chain, comparing with other typical schemes

Improving Security of Crypto Wallets in Blockchain Technologies

A big challenge in blockchain and cryptocurrency is securing the private key from potential hackers. Nobody can rollback a transaction made with a stolen key once the network confirms it. The technical solution to protect private keys is the cryptocurrency wallet, software, hardware, or a combination to manage the keys. In this dissertation, we try to investigate the significant challenges in existing cryptocurrency wallets and propose innovative solutions. Firstly, almost all cryptocurrency wallets suffer from the lack of a secure and convenient backup and recovery process. We offer a new cryptographic scheme to securely back up a hardware wallet relying on the side-channel human visual verification on the hardware wallet. Another practical mechanism to protect the funds is splitting the money between two wallets with small and large amounts. We propose a new scheme to create hierarchical wallets that we call deterministic sub-wallet to achieve this goal. The user can send funds from the wallet with a large amount to a smaller one in a secure way. We propose a multilayered architecture for cryptocurrency wallets based on a Defense-in-Depth strategy to protect private keys with a balance between convenience and security. The user protects the private keys in three restricted layers with different protection mechanisms. Finally, we try to solve another challenge in cryptocurrencies, which is losing access to private keys by its user, resulting in inaccessible coins. We propose a new mechanism called lean recovery transaction to tackle this problem. We make a change in wallet key management to generate a recovery transaction when needed. We implement a proof-of-concept for all of our proposals on a resource-constraint hardware wallet with a secure element, an embedded display, and one physical button. Furthermore, we evaluate the performance of our implementation and analyze the security of our proposed mechanisms

Surveillance and identity: conceptual framework and formal models

Surveillance is recognised as a social phenomenon that is commonplace, employed by governments, companies and communities for a wide variety of reasons. Surveillance is fundamental in cybersecurity as it provides tools for prevention and detection; it is also a source of controversies related to privacy and freedom. Building on general studies of surveillance, we identify and analyse certain concepts that are central to surveillance. To do this we employ formal methods based on elementary algebra. First, we show that disparate forms of surveillance have a common structure and can be unified by abstract mathematical concepts. The model shows that (i) finding identities and (ii) sorting identities into categories are fundamental in conceptualising surveillance. Secondly, we develop a formal model that theorizes identity as abstract data that we call identifiers. The model views identity through the computational lens of the theory of abstract data types. We examine the ways identifiers depend upon each other; and show that the provenance of identifiers depends upon translations between systems of identifiers

User authentication and remote execution across administrative domains

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 73-77).(cont.) selectively delegates authority to processes running on remote machines that need to access other resources. The delegation mechanism lets users incrementally construct trust policies for remote machines. Measurements of the system demonstrate that the modularity of REX's architecture does not come at the cost of performance.A challenge in today's Internet is providing easy collaboration across administrative boundaries. Using and sharing resources between individuals in different administrative domains should be just as easy and secure as sharing them within a single domain. This thesis presents a new authentication service and a new remote login and execution utility that address this challenge. The authentication service contributes a new design point in the space of user authentication systems. The system provides the flexibility to create cross-domain groups in the context of a global, network file system using a familiar, intuitive interface for sharing files that is similar to local access control mechanisms. The system trades off freshness for availability by pre-fetching and caching remote users and groups defined in other administrative domains, so the file server can make authorization decisions at file-access time using only local information. The system offers limited privacy for group lists and has all-or-nothing delegation to other administrative domains via nested groups. Experiments demonstrate that the authentication server scales to groups with tens of thousands of members. REX contributes a new architecture for remote execution that offers extensibility and security. To achieve extensibility, REX bases much of its functionality on a single new abstraction-emulated file descriptor passing across machines. This abstraction is powerful enough for users to extend REX's functionality in many ways without changing the core software or protocol. REX addresses security in two ways. First, the implementation internally leverages file descriptor passing to split the server into several smaller programs, reducing both privileged and remotely exploitable code. Second, REXby Michael Kaminsky.Ph.D

Security Threats Classification in Blockchains

Blockchain, the foundation of Bitcoin, has become one of the most popular technologies to create and manage digital transactions recently. It serves as an immutable ledger which allows transactions take place in a decentralized manner. This expeditiously evolving technology has the potential to lead to a shift in thinking about digital transactions in multiple sectors including, Internet of Things, healthcare, energy, supply chain, manufacturing, cybersecurity and principally financial services. However, this emerging technology is still in its infancy. Despite the huge opportunities blockchain offers, it suffers from challenges and limitation such as scalability, security, and privacy, compliance, and governance issues that have not yet been thoroughly explored and addressed. Although there are some studies on the security and privacy issues of the blockchain, they lack a systematic examination of the security of blockchain systems. This research conducted a systematic survey of the security threats to the blockchain systems and reviewed the existing vulnerabilities in the Blockchain. These vulnerabilities lead to the execution of the various security threats to the normal functionality of the Blockchain platforms. Moreover, the study provides a case-study for each attack by examining the popular blockchain systems and also reviews possible countermeasures which could be used in the development of various blockchain systems. Furthermore, this study developed taxonomies that classified the security threats and attacks based on the blockchain abstract layers, blockchain primary processes and primary business users. This would assist the developers and businesses to be attentive to the existing threats in different areas of the blockchain-based platforms and plan accordingly to mitigate risk. Finally, summarized the critical open challenges, and suggest future research directions