Ultrasound and near-ultrasound acoustic frequencies offer non-intrusive and low-overhead mediums for data transmission protocols. These protocols and the technologies built upon them are becoming more prevalent, yet their security remains largely unexplored. We present the first systematization of ultrasound and near-ultrasound enabled applications, developing a unified threat model to address their security. Our analysis reveals misguided assumptions, missing protections, and the need for standardization. Through our taxonomy, we highlight key insights, future research directions, and propose a framework for securing these protocols.

Smartphones form an important source of trust in modern computing. But, while their mobility is convenient, smartphones can be stolen or seized, allowing an adversary to impersonate the user in their digital life: accessing the user's services and decrypting their sensitive files. With this in mind, we build SocIoTy, which leverages a user's existing IoT devices to add a context-sensitive layer of security for non-expert users. Instead of assuming the existence of dedicated hardware, SocIoTy re-uses the devices of a user's smart home to provide cryptographic services, which we term at-home cryptography. We show that at-home cryptography can be built from simple cryptographic primitives, and that our SocIoTy solution is able to provide useful functionalities, like two-factor authentication (2FA) and secure file storage, while protecting against powerful adversaries in this setting. We implement and evaluate SocIoTy in real-world use cases and provide microbenchmarks for individual cryptographic operations on realistic models of IoT devices. We also provide full benchmarks of an end-to-end deployment on a simulated smart home, using a smartphone and 9 IoT devices to generate and display 2FA one-time passwords in less than 200 milliseconds. SocIoTy is able to provide strong, practical cryptography while binding its execution to the smart home itself, all without requiring additional hardware.

Despite a long history of research and wide-spread applications to censorship resistant systems, practical steganographic systems capable of embedding messages into realistic communication distributions, like text, do not exist. We identify two primary impediments to deploying universal steganography: (1) prior work leaves the difficult problem of finding samplers for non-trivial distributions unaddressed, and (2) prior constructions have impractical minimum entropy requirements. We investigate using generative models as steganographic samplers, as they represent the best known technique for approximating human communication. Additionally, we study methods to overcome the entropy requirement, including evaluating existing techniques and designing a new steganographic protocol, called Meteor. The resulting protocols are provably indistinguishable from honest model output and represent an important step towards practical steganographic communication for mundane communication channels. We implement Meteor and evaluate it on multiple computation environments with multiple generative models.

As an avid poker player, I enjoyed playing low stakes cash games and low buy-in tournaments on Full Tilt Poker before Black Friday.i However, as a Computer Scientist specializing in network and software security, I would never play poker online for any significant stakes, due to security concerns around malware and malicious remote access tools. Similarly, malware and remote access tools threaten online banking, online access to healthcare records and many other applications. In this article, I describe a new solution to the problem of remote access via malware that is easy to adopt, requires no new hardware or user training, and which I believe greatly reduces the threats to online applications.

Balancing security, privacy, safety, and utility is a necessity in the health care domain, in which implantable medical devices (IMDs) and body area networks (BANs) have made it possible to continuously and automatically manage and treat a number of health conditions. In this work, we survey publications aimed at improving security and privacy in IMDs and health-related BANs, providing clear definitions and a comprehensive overview of the problem space. We analyze common themes, categorize relevant results, and identify trends and directions for future research. We present a visual illustration of this analysis that shows the progression of IMD/BAN research and highlights emerging threats. We identify three broad research categories aimed at ensuring the security and privacy of the telemetry interface, software, and sensor interface layers and discuss challenges researchers face with respect to ensuring reproducibility of results. We find that while the security of the telemetry interface has received much attention in academia, the threat of software exploitation and the sensor interface layer deserve further attention. In addition, we observe that while the use of physiological values as a source of entropy for cryptographic keys holds some promise, a more rigorous assessment of the security and practicality of these schemes is required.

Bitcoin is the first e-cash system to see widespread adoption. While Bitcoin offers the potential for new types of financial interaction, it has significant limitations regarding privacy. Specifically, because the Bitcoin transaction log is completely public, users' privacy is protected only through the use of pseudonyms. In this paper we propose Zerocoin, a cryptographic extension to Bitcoin that augments the protocol to allow for fully anonymous currency transactions. Our system uses standard cryptographic assumptions and does not introduce new trusted parties or otherwise change the security model of Bitcoin. We detail Zerocoin's cryptographic construction, its integration into Bitcoin, and examine its performance both in terms of computation and impact on the Bitcoin protocol.

We develop a new technique whereby a poll worker can determine whether the software executing on electronic voting machines on election day has been altered from its factory version. Our generalized approach allows a human, using a known challenge-response pair, to detect attacks that involve modification or replacement of software on a computer based on the time it takes the computer to provide a correct response to a challenge. We exploit the large difference between main memory access times and cache memory access or CPU clock cycle times to significantly increase the time required to compute the right response when the software has been changed.

The 13 papers in this special issue focus on electronic voting.

The electronic voting machines known as Direct Recording Electronic (DRE), that are used in many states in the US have been shown to contain security vulnerabilities [16, 9, 3]. One of the problems is that the elections held on these machines cannot be independently audited. In this paper we address this issue by designing a new all-electronic independent audit framework for DRE voting systems. Our framework leverages system virtualization concepts and image recognition techniques to maintain an audit of the vote totals. The architecture we present is a step towards meeting the software independence requirements as defined by Rivest et al. [21, 2]. We have implemented a prototype using the Diebold Accuvote TS DRE voting software and the XEN hypervisor and demonstrate that our system can achieve a robust election audit with negligible overhead.

The stability and robustness of BGP remains one of the most critical elements in sustaining today’s Internet. In this paper, we study the structure and stability of origin advertisements in inter-domain routing. We visualize and quantitatively characterize the frequency, size, and effect of address assignment and origin changes by analyzing realworld BGP updates for a period of one year from multiple vantage points. Broad classes of prefix behaviors are developed. We show that a significant portion of BGP traffic is due to prefix flapping and explore the contributing factors which include a number of prefixes with abnormal short upand- down cycles. A significant portion of prefixes have high origin stability. Most ASes are involved in few, if any, prefix movement events, while a small number of ASes are responsible for most of the origin churn. Additionally, we find that a high volume of new prefixes can be attributed to actively evolving countries, that some abnormal prefix flapping is most likely due to misconfiguration, and that some culprit ASes characterize the places where multi-origin prefixes oscillate.

With significant U.S. federal funds now available to replace outdated punch-card and mechanical voting systems, municipalities and states throughout the U.S. are adopting paperless electronic voting systems from a number of different vendors. We present a security analysis of the source code to one such machine used in a significant share of the market. Our analysis shows that this voting system is far below even the most minimal security standards applicable in other contexts. We identify several problems including unauthorized privilege escalation, incorrect use of cryptography, vulnerabilities to network threats, and poor software development processes. We show that voters, without any insider privileges, can cast unlimited votes without being detected by any mechanisms within the voting terminal software. Furthermore, we show that even the most serious of our outsider attacks could have been discovered and executed without access to the source code. In the face of such attacks, the usual worries about insider threats are not the only concerns; outsiders can do the damage. That said, we demonstrate that the insider threat is also quite considerable, showing that not only can an insider, such as a poll worker, modify the votes, but that insiders can also violate voter privacy and match votes with the voters who cast them. We conclude that this voting system is unsuitable for use in a general election. Any paperless electronic voting system might suffer similar flaws, despite any certification it could have otherwise received. We suggest that the best solutions are voting systems having a voter-verifiable audit trail, where a computerized voting system might print a paper ballot that can be read and verified by the voter.

In this paper, we present a practical key recovery attack on WEP, the link-layer security protocol for 802.11b wireless networks. The attack is based on a partial key exposure vulnerability in the RC4 stream cipher discovered by Fluhrer, Mantin, and Shamir. This paper describes how to apply this flaw to breaking WEP, our implementation of the attack, and optimizations that can be used to reduce the number of packets required for the attack. We conclude that the 802.11b WEP standard is completely insecure, and we provide recommendations on how this vulnerability could be mitigated and repaired.

We discuss the dangers that scalable Internet functionality may present to the real world, focusing upon an attack that is simple, yet can have great impact, which we believe may occur quite soon. We offer and critique various solutions to this class of attack and hope to provide a warning to the Internet community of what is currently possible. The attack is, to some degree, a consequence of the availability of private information on the Web, and the increase in the amount of personal information that users must reveal to obtain Web services.

The Internet in its present form does not protect content from censorship. It is straightforward to trace any document back to a specific Web server, and usually directly to an individual. As we discuss below, there are valid reasons for publishing a document in a censorship-resistant manner. Unfortunately, few tools exist that facilitate this form of publishing. We describe the architecture of robust systems for publishing content on the Web. The discussion is in the context of Publius, as that system meets the most design goals of currently deployed systems. Publius has the property that it is very difficult for any adversary to censor or modify the content. In addition, the identity of the publisher is protected once the content is posted. The system differs from others in that tools are provided for updating or deleting published content, and users can browse the content in the normal point-and-click manner using a standard Web browser and a client-side proxy.

More than ever before the Internet is changing computing as we know it. Global access to information and resources is becoming an integral part of nearly every aspect of our lives. Unfortunately, with this global network access comes increased chances of malicious attack and intrusion. In an effort to confront the new threats unveiled by the networking revolution of the past few years reliable, rapid, and unintrusive means for automatically recognizing the identity of individuals are now being sought. In this paper we examine an emerging non-static biometric technique that aims to identify users based on analyzing habitual rhythm patterns in the way they type.

We introduce a technique for using an untrusted device, such as a hand-held personal digital assistant or a laptop to perform real financial transactions without a network. We utilize the tamper-resistant nature of smartcards to store value on them and perform probabilistic computations based on user input. We discuss an application of this to gambling. The technique has the properties that the user is guaranteed to make money when he wins and the house is guaranteed to make money when the user loses. 1 Introduction We are currently experiencing a proliferation of lightweight handheld devices, such as the 3Com palm pilot, windows CE devices, and even laptops that weigh under three pounds. Many of these devices are so portable that people have them in their pockets and use them at all times. Our goal is to enable people to utilize these devices during otherwise dead time perhaps at the doctor's office, or in line at the supermarket. We are interested in utilizing the time when the us...

Mobile code presents a number of threats to machines that execute it. We introduce an approach for protecting machines and the resources they hold from mobile code, and describe a system based on our approach for protecting host machines from Java 1.1 applets. In our approach, each Java applet downloaded to the protected domain is rerouted to a dedicated machine (or set of machines), the playground, at which it is executed. Prior to execution, the applet is transformed to use the downloading user's Web browser as a graphics terminal for its input and output, and so the user has the illusion that the applet is running on her own machine. In reality, however, mobile code runs only in the sanitized environment of the playground, where user files cannot be mounted and from which only limited network connections are accepted by machines in the protected domain. Our playground thus provides a second level of defense against mobile code that circumvents language based defenses.

In this paper we introduce a system called Crowds for protecting users' anonymity on the world-wide-web. Crowds, named for the notion of “blending into a crowd,” operates by grouping users into a large and geographically diverse group (crowd) that collectively issues requests on behalf of its members. Web servers are unable to learn the true source of a request because it is equally likely to have originated from any member of the crowd, and even collaborating crowd members cannot distinguish the originator of a request from a member who is merely forwarding the request on behalf of another. We describe the design, implementation, security, performance, and scalability of our system. Our security analysis introduces degrees of anonymity as an important tool for describing and proving anonymity properties.

In an effort to confront the challenges brought forward by the networking revolution of the past few years, we present im-proved techniques for authorized access to computer system resources and data. More than ever before, the Internet is changing computing as we know it. The possibilities of this global network seem limitless; unfortunately, with this global access comes increased chances of malicious attack and in-trusion. Alternatives to traditional access control measures are in high demand. In what follows we present one such alternative: computer access via keystroke dynamics. A database of 42 profiles was constructed based on key-stroke patterns gathered from various users performing struc-tured and unstructured tasks. We study the performance of a system for recognition of these users, and present a toolkit for analyzing system performance under varying criteria.

This paper explores the problem of protecting a site on the Internet against hostile external Java applets while allowing trusted internal applets to run. With careful implementation, a site can be made resistant to current Java security weaknesses as well as those yet to be discovered. In addition, we describe a new attack on certain sophisticated firewalls that is most effectively realized as a Java applet.

We present a service for locating and retrieving files from an untrusted network such that the integrity of the retrieved files can be verified. This service enables groups of people in geographically remote locations to share files using an untrusted network. For example, distribution, of an organization's software to all the organization's sites can be accomplished using this service. Distribution of files in an untrusted network is complicated by two issues: (1) location of files and (2) verification of file integrity. ftp and World-wide Web (WWW) services require some user intervention to locate a file, so they cannot be embedded in automated systems. Distributed systems have mechanisms for automated file location and retrieval, but they require trust in all system principals and do not provide an appropriate balance between availability of files and retrieval cost for our applications. Verification of the integrity of a file retrieved from an untrusted network is necessary because the file is subject to malicious modification attacks. Our service provides the capability to automatically locate, retrieve, and verify files specified by a client using a single trusted principal. We demonstrate our service by building a system shell that automatically downloads remote software when needed.

This paper presents extensions to a technique for specifying and analyzing nonmonotonic cryptographic protocols (NCP) that use asymmetric keys. We introduce new actions and inference rules, as well as slight modifications to the update function. An important observation is that reasoning about the origin of messages is quite different when dealing with asymmetric key protocols. We also introduce the notion that keys in certificates should be bound to the principals receiving them. We extend the technique to meet the binding requirements and show how the flaw in the Denning and Sacco (1981) public key protocol, that was discovered by Abadi and Needham (1994), is revealed. We demonstrate the extended technique using one protocol of our own and the Needham and Schroeder (1978) public key protocol. Finally, we introduce and analyze a fix to a known weakness in Needham and Schroeder's protocol using our extended technique.

The paper offers a solution to a problem of software distribution on the lnternet. The problem is that malicious software can be posted to the public with no accountability. When this software is run, it inherits the privileges of the user who runs it. Unfortunately, it is very common for users to execute software obtained on the Internet with no assurance that it is genuine. The solution offered here utilizes a trusted third party that signs certificates to identify the author of a program and to secure its integrity. A detailed design is provided. Finally, Bellcore's Trusted Software Integrity (Betsi) System, an implementation of the design, is presented.>

The paper presents a new method for specifying and analyzing cryptographic protocols. The method offers several advantages over previous approaches. The technique is the first to allow reasoning about nonmonotonic protocols, which are needed for systems that rely on the deletion of information. There is no idealization of protocols; we specify at a level that is close to the actual implementation. We show how the method uncovers the known flaw in the Needham and Schroeder protocol (R.M. Needham and M.D. Schroeder, 1978). We then apply the method to the khat protocol (A.D. Rubin, P. Honeyman, 1993). The analysis reveals a serious, previously undiscovered flaw in the nonmonotonic protocol for long-running jobs.>