Authentication and Key Management Automation in Decentralized Secure Email and Messaging via Low-Entropy Secrets

We revisit the problem of entity authentication in decentralized end-to-end encrypted email and secure messaging to propose a practical and self-sustaining cryptographic solution based on password-authenticated key exchange (PAKE). This not only allows users to authenticate each other via shared low-entropy secrets, e.g., memorable words, without a public key infrastructure or a trusted third party, but it also paves the way for automation and a series of cryptographic enhancements; improves security by minimizing the impact of human error and potentially improves usability. First, we study a few vulnerabilities in voice-based out-of-band authentication, in particular a combinatorial attack against lazy users, which we analyze in the context of a secure email solution. Next, we propose solving the problem of secure equality test using PAKE to achieve entity authentication and to establish a shared high-entropy secret key. Our solution lends itself to offline settings, compatible with the inherently asynchronous nature of email and modern messaging systems. The suggested approach enables enhancements in key management such as automated key renewal and future key pair authentications, multi-device synchronization, secure secret storage and retrieval, and the possibility of post-quantum security as well as facilitating forward secrecy and deniability in a primarily symmetric-key setting. We also discuss the use of auditable PAKEs for mitigating a class of online guess and abort attacks in authentication protocols

From Understanding Telephone Scams to Implementing Authenticated Caller ID Transmission

abstract: The telephone network is used by almost every person in the modern world. With the rise of Internet access to the PSTN, the telephone network today is rife with telephone spam and scams. Spam calls are significant annoyances for telephone users, unlike email spam, spam calls demand immediate attention. They are not only significant annoyances but also result in significant financial losses in the economy. According to complaint data from the FTC, complaints on illegal calls have made record numbers in recent years. Americans lose billions to fraud due to malicious telephone communication, despite various efforts to subdue telephone spam, scam, and robocalls. In this dissertation, a study of what causes the users to fall victim to telephone scams is presented, and it demonstrates that impersonation is at the heart of the problem. Most solutions today primarily rely on gathering offending caller IDs, however, they do not work effectively when the caller ID has been spoofed. Due to a lack of authentication in the PSTN caller ID transmission scheme, fraudsters can manipulate the caller ID to impersonate a trusted entity and further a variety of scams. To provide a solution to this fundamental problem, a novel architecture and method to authenticate the transmission of the caller ID is proposed. The solution enables the possibility of a security indicator which can provide an early warning to help users stay vigilant against telephone impersonation scams, as well as provide a foundation for existing and future defenses to stop unwanted telephone communication based on the caller ID information.Dissertation/ThesisDoctoral Dissertation Computer Science 201

Hardware-Assisted Secure Computation

The theory community has worked on Secure Multiparty Computation (SMC) for more than two decades, and has produced many protocols for many settings. One common thread in these works is that the protocols cannot use a Trusted Third Party (TTP), even though this is conceptually the simplest and most general solution. Thus, current protocols involve only the direct players---we call such protocols self-reliant. They often use blinded boolean circuits, which has several sources of overhead, some due to the circuit representation and some due to the blinding. However, secure coprocessors like the IBM 4758 have actual security properties similar to ideal TTPs. They also have little RAM and a slow CPU.We call such devices Tiny TTPs. The availability of real tiny TTPs opens the door for a different approach to SMC problems. One major challenge with this approach is how to execute large programs on large inputs using the small protected memory of a tiny TTP, while preserving the trust properties that an ideal TTP provides. In this thesis we have investigated the use of real TTPs to help with the solution of SMC problems. We start with the use of such TTPs to solve the Private Information Retrieval (PIR) problem, which is one important instance of SMC. Our implementation utilizes a 4758. The rest of the thesis is targeted at general SMC. Our SMC system, Faerieplay, moves some functionality into a tiny TTP, and thus avoids the blinded circuit overhead. Faerieplay consists of a compiler from high-level code to an arithmetic circuit with special gates for efficient indirect array access, and a virtual machine to execute this circuit on a tiny TTP while maintaining the typical SMC trust properties. We report on Faerieplay\u27s security properties, the specification of its components, and our implementation and experiments. These include comparisons with the Fairplay circuit-based two-party system, and an implementation of the Dijkstra graph shortest path algorithm. We also provide an implementation of an oblivious RAM which supports similar tiny TTP-based SMC functionality but using a standard RAM program. Performance comparisons show Faerieplay\u27s circuit approach to be considerably faster, at the expense of a more constrained programming environment when targeting a circuit

Distributed, end-to-end verifiable, and privacy-preserving internet voting systems

We present the D-DEMOS suite of distributed, privacy-preserving, and end-to-end verifiable e-voting systems; one completely asynchronous and one with minimal timing assumptions but better performance. Their distributed voting operation is human verifiable; a voter can vote over the web, using an unsafe web client stack, without sacrificing her privacy, and get recorded-as-cast assurance. Additionally, a voter can outsource election auditing to third parties, still without sacrificing privacy. We provide a model and security analysis of the systems, implement prototypes of the complete systems, measure their performance experimentally, demonstrate their ability to handle large-scale elections, and demonstrate the performance trade-offs between the two versions

Data Minimisation in Communication Protocols: A Formal Analysis Framework and Application to Identity Management

With the growing amount of personal information exchanged over the Internet, privacy is becoming more and more a concern for users. One of the key principles in protecting privacy is data minimisation. This principle requires that only the minimum amount of information necessary to accomplish a certain goal is collected and processed. "Privacy-enhancing" communication protocols have been proposed to guarantee data minimisation in a wide range of applications. However, currently there is no satisfactory way to assess and compare the privacy they offer in a precise way: existing analyses are either too informal and high-level, or specific for one particular system. In this work, we propose a general formal framework to analyse and compare communication protocols with respect to privacy by data minimisation. Privacy requirements are formalised independent of a particular protocol in terms of the knowledge of (coalitions of) actors in a three-layer model of personal information. These requirements are then verified automatically for particular protocols by computing this knowledge from a description of their communication. We validate our framework in an identity management (IdM) case study. As IdM systems are used more and more to satisfy the increasing need for reliable on-line identification and authentication, privacy is becoming an increasingly critical issue. We use our framework to analyse and compare four identity management systems. Finally, we discuss the completeness and (re)usability of the proposed framework

Detection of HTTPS brute-force attacks in high-speed computer networks

Tato práce představuje přehled metod pro detekci síťových hrozeb se zaměřením na útoky hrubou silou proti webovým aplikacím, jako jsou WordPress a Joomla. Byl vytvořen nový dataset, který se skládá z provozu zachyceného na páteřní síti a útoků generovaných pomocí open-source nástrojů. Práce přináší novou metodu pro detekci útoku hrubou silou, která je založena na charakteristikách jednotlivých paketů a používá moderní metody strojového učení. Metoda funguje s šifrovanou HTTPS komunikací, a to bez nutnosti dešifrování jednotlivých paketů. Stále více webových aplikací používá HTTPS pro zabezpečení komunikace, a proto je nezbytné aktualizovat detekční metody, aby byla zachována základní viditelnost do síťového provozu.This thesis presents a review of flow-based network threat detection, with the focus on brute-force attacks against popular web applications, such as WordPress and Joomla. A new dataset was created that consists of benign backbone network traffic and brute-force attacks generated with open-source attack tools. The thesis proposes a method for brute-force attack detection that is based on packet-level characteristics and uses modern machine-learning models. Also, it works with encrypted HTTPS traffic, even without decrypting the payload. More and more network traffic is being encrypted, and it is crucial to update our intrusion detection methods to maintain at least some level of network visibility

The Prom Problem: Fair and Privacy-Enhanced Matchmaking with Identity Linked Wishes

In the Prom Problem (TPP), Alice wishes to attend a school dance with Bob and needs a risk-free, privacy preserving way to find out whether Bob shares that same wish. If not, no one should know that she inquired about it, not even Bob. TPP represents a special class of matchmaking challenges, augmenting the properties of privacy-enhanced matchmaking, further requiring fairness and support for identity linked wishes (ILW) – wishes involving specific identities that are only valid if all involved parties have those same wishes. The Horne-Nair (HN) protocol was proposed as a solution to TPP along with a sample pseudo-code embodiment leveraging an untrusted matchmaker. Neither identities nor pseudo-identities are included in any messages or stored in the matchmaker’s database. Privacy relevant data stay within user control. A security analysis and proof-of-concept implementation validated the approach, fairness was quantified, and a feasibility analysis demonstrated practicality in real-world networks and systems, thereby bounding risk prior to incurring the full costs of development. The SecretMatch™ Prom app leverages one embodiment of the patented HN protocol to achieve privacy-enhanced and fair matchmaking with ILW. The endeavor led to practical lessons learned and recommendations for privacy engineering in an era of rapidly evolving privacy legislation. Next steps include design of SecretMatch™ apps for contexts like voting negotiations in legislative bodies and executive recruiting. The roadmap toward a quantum resistant SecretMatch™ began with design of a Hybrid Post-Quantum Horne-Nair (HPQHN) protocol. Future directions include enhancements to HPQHN, a fully Post Quantum HN protocol, and more

An Historical Analysis of Factors Contributing to the Emergence of the Intrusion Detection Discipline and its Role in Information Assurance

In 2003, Gartner, Inc., predicted the inevitable demise of the intrusion detection (ID) market, a major player in the computer security technology industry. In light of this prediction, IT executives need to know if intrusion detection technologies serve a strategic purpose within the framework of information assurance (IA). This research investigated the historical background and circumstances that led to the birth of the intrusion detection field and explored the evolution of the discipline through current research in order to identify appropriate roles for IDS technology within an information assurance framework. The research identified factors contributing to the birth of ID including increased procurement and employment of resource-sharing computer systems in the DoD, a growing need to operate in an open computing environment while maintaining security and the unmanageable volume of audit data produced as a result of security requirements. The research also uncovered six trends that could be used to describe the evolution of the ID discipline encompassing passive to active response mechanisms, centralized to distributed management platforms, centralized to distributed/agent-based detection, single to multiple detection approaches within a system, host-based to network to hybrid analysis and software-based to hardware-based/in-line devices. Finally, the research outlined three roles suitable for IDS to fulfill within the IA framework including employing IDS as a stimulus to incident response mechanisms, as a forensic tool for gathering evidence of computer misuse and as a vulnerability assessment or policy enforcement facility

Nation-State Attackers and their Effects on Computer Security

Nation-state intelligence agencies have long attempted to operate in secret, but recent revelations have drawn the attention of security researchers as well as the general public to their operations. The scale, aggressiveness, and untargeted nature of many of these now public operations were not only alarming, but also baffling as many were thought impossible or at best infeasible at scale. The security community has since made many efforts to protect end-users by identifying, analyzing, and mitigating these now known operations. While much-needed, the security community's response has largely been reactionary to the oracled existence of vulnerabilities and the disclosure of specific operations. Nation-State Attackers, however, are dynamic, forward-thinking, and surprisingly agile adversaries who do not rest on their laurels and are continually advancing their efforts to obtain information. Without the ability to conceptualize their actions, understand their perspective, or account for their presence, the security community's advances will become antiquated and unable to defend against the progress of Nation-State Attackers. In this work, we present and discuss a model of Nation-State Attackers that can be used to represent their attributes, behavior patterns, and world view. We use this representation of Nation-State Attackers to show that real-world threat models do not account for such highly privileged attackers, to identify and support technical explanations of known but ambiguous operations, and to identify and analyze vulnerabilities in current systems that are favorable to Nation-State Attackers.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/143907/1/aaspring_1.pd