Authenticated Data Structures as Functors in Isabelle/HOL

Merkle trees are ubiquitous in blockchains and other distributed ledger technologies (DLTs). They guarantee that the involved systems are referring to the same binary tree, even if each of them knows only the cryptographic hash of the root. Inclusion proofs allow knowledgeable systems to share subtrees with other systems and the latter can verify the subtrees\u27 authenticity. Often, blockchains and DLTs use data structures more complicated than binary trees; authenticated data structures generalize Merkle trees to such structures. We show how to formally define and reason about authenticated data structures, their inclusion proofs, and operations thereon as datatypes in Isabelle/HOL. The construction lives in the symbolic model, i.e., we assume that no hash collisions occur. Our approach is modular and allows us to construct complicated trees from reusable building blocks, which we call Merkle functors. Merkle functors include sums, products, and function spaces and are closed under composition and least fixpoints. As a practical application, we model the hierarchical transactions of Canton, a practical interoperability protocol for distributed ledgers, as authenticated data structures. This is a first step towards formalizing the Canton protocol and verifying its integrity and security guarantees

TrusNet: Peer-to-Peer Cryptographic Authentication

Originally, the Internet was meant as a general purpose communication protocol, transferring primarily text documents between interested parties. Over time, documents expanded to include pictures, videos and even web pages. Increasingly, the Internet is being used to transfer a new kind of data which it was never designed for. In most ways, this new data type fits in naturally to the Internet, taking advantage of the near limit-less expanse of the protocol. Hardware protocols, unlike previous data types, provide a unique set security problem. Much like financial data, hardware protocols extended across the Internet must be protected with authentication. Currently, systems which do authenticate do so through a central server, utilizing a similar authentication model to the HTTPS protocol. This hierarchical model is often at odds with the needs of hardware protocols, particularly in ad-hoc networks where peer-to-peer communication is prioritized over a hierarchical model. Our project attempts to implement a peer-to-peer cryptographic authentication protocol to be used to protect hardware protocols extending over the Internet. The TrusNet project uses public-key cryptography to authenticate nodes on a distributed network, with each node locally managing a record of the public keys of nodes which it has encountered. These keys are used to secure data transmission between nodes and to authenticate the identities of nodes. TrusNet is designed to be used on multiple different types of network interfaces, but currently only has explicit hooks for Internet Protocol connections. As of June 2016, TrusNet has successfully achieved a basic authentication and communication protocol on Windows 7, OSX, Linux 14 and the Intel Edison. TrusNet uses RC-4 as its stream cipher and RSA as its public-key algorithm, although both of these are easily configurable. Along with the library, TrusNet also enables the building of a unit testing suite, a simple UI application designed to visualize the basics of the system and a build with hooks into the I/O pins of the Intel Edison allowing for a basic demonstration of the system

Interoperable ADS-B Confidentiality

The worldwide air traffic infrastructure is in the late stages of transition from legacy transponder systems to Automatic Dependent Surveillance - Broadcast (ADS-B) based systems. ADS-B relies on position information from GNSS and requires aircraft to transmit their identification, state, and position. ADS-B promises the availability of high-fidelity air traffic information; however, position and identification data are not secured via authentication or encryption. This lack of security for ADS-B allows non-participants to observe and collect data on both government and private flight activity. This is a proposal for a lightweight, interoperable ADS-B confidentiality protocol which uses existing format preserving encryption and an innovative unidirectional key handoff to ensure backward compatibility. Anonymity and data confidentiality are achieved selectively on a per-session basis. This research also investigates the effect of false replies unsynchronized in time (FRUIT) on the packet error ratio (PER) for Mode S transmissions. High PERs result in range and time limits being imposed on the key handoff mechanism of this proposal. Overall, this confidentiality protocol is ready for implementation, however further research is required to validate a revised key handoff mechanism

Security Improvements for the Automatic Identification System

The Automatic Identification System (AIS) is used aboard the vast majority of sea-going vessels in the world as a collision avoidance tool. Currently, the AIS operates without any security features, which make it vulnerable to exploits such as spoofing, hijacking, and replay attacks by malicious parties. This paper examines the work that has been done so far to improve AIS security, as well as the approaches taken on similar problems in the aircraft and vehicular mobile ad-hoc network (MANET) industries. The first major contribution of this paper is the implementation of a Software Defined Radio (SDR) AIS transmitter and receiver which can be used to conduct vulnerability analysis and test the implementation of new security features. The second contribution is the design of a novel authentication protocol which overcomes the existing vulnerabilities in the AIS system. The proposed protocol uses time-delayed hash-chain key disclosures as part of a message authentication code (MAC) appended to automatic position reports to verify the authenticity of a user. This method requires only one additional time slot for broadcast authentication compared to the existing standard and is a significant reduction in message overhead requirements compared to alternative approaches that solely rely on public key infrastructure (PKI). Additionally, there is an embedded time stamp, a feature lacking in the existing system, which makes this protocol resistant to replay attacks. A test implementation of the proposed protocol indicates that it can be deployed as a link layer software update to existing AIS transceivers and can be deployed within the current AIS technical standards as an expanded message set

Real-Time Sensor Networks and Systems for the Industrial IoT

The Industrial Internet of Things (Industrial IoT—IIoT) has emerged as the core construct behind the various cyber-physical systems constituting a principal dimension of the fourth Industrial Revolution. While initially born as the concept behind specific industrial applications of generic IoT technologies, for the optimization of operational efficiency in automation and control, it quickly enabled the achievement of the total convergence of Operational (OT) and Information Technologies (IT). The IIoT has now surpassed the traditional borders of automation and control functions in the process and manufacturing industry, shifting towards a wider domain of functions and industries, embraced under the dominant global initiatives and architectural frameworks of Industry 4.0 (or Industrie 4.0) in Germany, Industrial Internet in the US, Society 5.0 in Japan, and Made-in-China 2025 in China. As real-time embedded systems are quickly achieving ubiquity in everyday life and in industrial environments, and many processes already depend on real-time cyber-physical systems and embedded sensors, the integration of IoT with cognitive computing and real-time data exchange is essential for real-time analytics and realization of digital twins in smart environments and services under the various frameworks’ provisions. In this context, real-time sensor networks and systems for the Industrial IoT encompass multiple technologies and raise significant design, optimization, integration and exploitation challenges. The ten articles in this Special Issue describe advances in real-time sensor networks and systems that are significant enablers of the Industrial IoT paradigm. In the relevant landscape, the domain of wireless networking technologies is centrally positioned, as expected

Investigation into the security and privacy of iOS VPN applications

Due to the increasing number of recommendations for people to use Virtual Private Networks (VPNs) to protect their privacy, more application developers are creating VPN applications and publishing them on the Apple App Store and Google Play Store. In this ‘gold rush’, applications are being developed quickly and, in turn, not being developed with security in mind.This paper investigated a selection of VPN applications available on the Apple App Store (for iOS devices) and tested the applications for security and privacy issues. This includes testing for any traffic being transmitted over plain HTTP, DNS leakage and transmission of personally identifiable information (such as phone number, International Mobile Equipment Identity (IMEI), email address, MAC address) and evaluating the security of the tunneling protocol used by the VPN.The testing methodology involved installing VPN applications on a test device, simulating network traffic for a pre-defined period of time and capturing the traffic. This allows for all traffic to be analysed to check for anything being sent without encryption. Other issues that often cause de-anonymization with VPN applications such as DNS leakage were also considered.The research found several common security issues with VPN applications tested, with a large majority of applications still using HTTP and not HTTPS for transmitting certain data. A large majority of the VPN applications failed to route additional user data (such as DNS queries) through the VPN tunnel. Furthermore, just fifteen of the tested applications were found to have correctly implemented the best-recommended tunneling protocol for user security.Outside of the regular testing criteria, other security anomalies were observed with specific applications, which included outdated servers with known vulnerabilities, applications giving themselves the ability to perform HTTPS interception and questionable privacy policies. From the documented vulnerabilities, this research proposes a set of recommendations for developers to consider when developing VPN applications

Security, Privacy and Economics of Online Advertising

Online advertising is at the core of today’s Web: it is the main business model, generating large annual revenues expressed in tens of billions of dollars that sponsor most of the online content and services. Online advertising consists of delivering marketing messages, embedded into Web content, to a targeted audience. In this model, entities attract Web traffic by offering the content and services for free and charge advertisers for including advertisements in this traffic (i.e., advertisers pay for users’ attention and interests). Online advertising is a very successful form of advertising as it allows for advertisements (ads) to be targeted to individual users’ interests; especially when advertisements are served on users’ mobile devices, as ads can be targeted to users’ locations and the corresponding context. However, online advertising also introduces a number of problems. Given the high ad revenue at stake, fraudsters have economic incentives to exploit the ad system and generate profit from it. Unfortunately, to achieve this goal, they often compromise users’ online security (e.g., via malware, phishing, etc.). For the purpose of maximizing the revenue by matching ads to users’ interests, a number of techniques are deployed, aimed at tracking and profiling users’ digital footprints, i.e., their behavior in the digital world. These techniques introduce new threats to users’ privacy. Consequently, some users adopt ad-avoidance tools that prevent the download of advertisements and partially thwart user profiling. Such user behavior, as well as exploits of ad systems, have economic implications as they undermine the online advertising business model. Meddling with advertising revenue disrupts the current economic model of the Web, the consequences of which are unclear. Given that today’s Web model relies on online advertising revenue in order for users to have access and consume content and services for “free”, coupled with the fact that there are many threats that could jeopardize this model, in this thesis we address the security, privacy and economic issues stemming from this fundamental element of the Web. In the first part of the thesis, we investigate the vulnerabilities of online advertising systems. We identify how an adversary can exploit the ad system to generate profit for itself, notably by performing inflight modification of ad traffic. We provide a proof-of-concept implementation of the identified threat on Wi-Fi routers. We propose a collaborative approach for securing online advertising and Web browsing against such threats. By investigating how a certificate-based authentication is deployed in practice, we assess the potential of relying on certificate-based authentication as a building block of a solution to protect the ad revenue. We propose a multidisciplinary approach for improving the current state of certificate-based authentication on the Web. In the second part of the thesis, we study the economics of ad systems’ exploits and certain potential countermeasures. We evaluate the potential of different solutions aimed at protecting ad revenue being implemented by the stakeholders (e.g., Internet Service Providers or ad networks) and the conditions under which this is likely to happen. We also study the economic ramifications of ad-avoidance technologies on the monetization of online content. We use game-theory to model the strategic behavior of involved entities and their interactions. In the third part of the thesis, we focus on privacy implications of online advertising. We identify a novel threat to users’ location privacy that enables service providers to geolocate users with high accuracy, which is needed to serve location-targeted ads for local businesses. We draw attention to the large scale of the threat and the potential impact on users’ location privacy