Traditionally, education in computer science focuses on stakeholders like teachers, undergraduate students, and employers. However researchers also educate themselves about recent results and new subject matters. An important vehicle in this informal, self-education process is reading peer-reviewed academic papers---papers that are also used in the curriculum of graduate-level research courses. Technical writing skills are important in this domain, as well as engaging the reader with interesting text. This paper is a study of academic writing. We study in depth the first sentence used by researchers in opening their academic papers and how this sentence operates to draw the reader in. We use a corpus of 379 papers from a top-tier cybersecurity conference and use qualitative analysis (coding from grounded theory) to create a taxonomy of 5 general types and 14 sub-types of opening sentences. In this paper, we define and illustrate each type through examples, and reflect on what we learned about writing after examining all of these sentences.

One fundamental limitation of blockchain-based smart contracts is that they execute in a closed environment. Thus, they only have access to data and functionality that is already on the blockchain, or is fed into the blockchain. Any interactions with the real world need to be mediated by a bridge service, which is called an oracle. As decentralized applications mature, oracles are playing an increasingly prominent role. With their evolution comes more attacks, necessitating greater attention to their trust model. In this systemization of knowledge paper (SoK), we dissect the design alternatives for oracles, showcase attacks, and discuss attack mitigation strategies.

This panel will explore how security topics are integrated into academic programs and future directions for improvements. It will address how early in time security should be introduced in programs like computer science and software engineering; and identify the critical takeaways that each graduating student should learn. We will try to separate out the important, practical concepts from the purely academic ones. We will also consider how well security programs translate to industry-focused needs: do students emerge with an understanding that is both deep and broad enough to be useful? In general, we will try to identify the pitfalls of current security education and how we can move forward as an academic community, in tandem with industry and government.

Bitcoin exchanges function like banks, securely holding customers' bitcoins on their behalf. Several exchanges have suffered catastrophic losses with customers permanently losing their savings. A proof of solvency demonstrates cryptographically that the exchange controls sufficient reserves to settle each customer's account. We introduce Provisions, a privacy-preserving proof of solvency whereby an exchange does not have to disclose its Bitcoin addresses; total holdings or liabilities; or any information about its customers. We also propose an extension which prevents exchanges from colluding to cover for each other's losses. We have implemented Provisions and it offers practical computation times and proof sizes even for a large Bitcoin exchange with millions of customers.

Bit coin has emerged as the most successful cryptographic currency in history. Within two years of its quiet launch in 2009, Bit coin grew to comprise billions of dollars of economic value despite only cursory analysis of the system's design. Since then a growing literature has identified hidden-but-important properties of the system, discovered attacks, proposed promising alternatives, and singled out difficult future challenges. Meanwhile a large and vibrant open-source community has proposed and deployed numerous modifications and extensions. We provide the first systematic exposition Bit coin and the many related crypto currencies or 'altcoins.' Drawing from a scattered body of knowledge, we identify three key components of Bit coin's design that can be decoupled. This enables a more insightful analysis of Bit coin's properties and future stability. We map the design space for numerous proposed modifications, providing comparative analyses for alternative consensus mechanisms, currency allocation mechanisms, computational puzzles, and key management tools. We survey anonymity issues in Bit coin and provide an evaluation framework for analyzing a variety of privacy-enhancing proposals. Finally we provide new insights on what we term disinter mediation protocols, which absolve the need for trusted intermediaries in an interesting set of applications. We identify three general disinter mediation strategies and provide a detailed comparison.

Android's trust-on-first-use application signing model associates developers with a fixed code signing certificate, but lacks a mechanism to enable transparent key updates or certificate renewals. The model allows application updates to be recognized as authorized by a party with access to the original signing key. However, changing keys or certificates requires that end users manually uninstall/reinstall apps, losing all non-backed up user data. In this paper, we show that with appropriate OS support, developers can securely and without user intervention transfer signing authority to a new signing key. Our proposal, Baton, modifies Android's app installation framework enabling key agility while preserving backwards compatibility with current apps and current Android releases. Baton is designed to work consistently with current UID sharing and signature permission requirements. We discuss technical details of the Android-specific implementation, as well as the applicability of the Baton protocol to other decentralized environments.

Internet users today depend daily on HTTPS for secure communication with sites they intend to visit. Over the years, many attacks on HTTPS and the certificate trust model it uses have been hypothesized, executed, and/or evolved. Meanwhile the number of browser-trusted (and thus, de facto, user-trusted) certificate authorities has proliferated, while the due diligence in baseline certificate issuance has declined. We survey and categorize prominent security issues with HTTPS and provide a systematic treatment of the history and on-going challenges, intending to provide context for future directions. We also provide a comparative evaluation of current proposals for enhancing the certificate infrastructure used in practice.

Passwords continue to prevail on the web as the primary method for user authentication despite their well-known security and usability drawbacks. Password managers offer some improvement without requiring server-side changes. In this paper, we evaluate the security of dual-possession authentication, an authentication approach offering encrypted storage of passwords and theft-resistance without the use of a master password. We further introduce Tapas, a concrete implementation of dual-possession authentication leveraging a desktop computer and a smartphone. Tapas requires no server-side changes to websites, no master password, and protects all the stored passwords in the event either the primary or secondary device (e.g., computer or phone) is stolen. To evaluate the viability of Tapas as an alternative to traditional password managers, we perform a 30 participant user study comparing Tapas to two configurations of Firefox's built-in password manager. We found users significantly preferred Tapas. We then improve Tapas by incorporating feedback from this study, and reevaluate it with an additional 10 participants.

In the above titled paper (ibid., vol. 4, no. 4, pp. 611-627, Dec. 09), due to a production error, the affiliations of two of the authors were listed incorrectly. The correct affiliations are presented here. Also, the name of the last author in the affiliations footnote was printed incorrectly. The correct name is P. Y. A. Ryan.

Scantegrity II is an enhancement for existing paper ballot systems. It allows voters to verify election integrity - from their selections on the ballot all the way to the final tally - by noting codes and checking for them online. Voters mark Scantegrity II ballots just as with conventional optical scan, but using a special ballot marking pen. Marking a selection with this pen makes legible an otherwise invisible preprinted confirmation code. Confirmation codes are independent and random for each potential selection on each ballot. To verify that their individual votes are recorded correctly, voters can look up their ballot serial numbers online and verify that their confirmation codes are posted correctly. The confirmation codes do not allow voters to prove how they voted. However, the confirmation codes constitute convincing evidence of error or malfeasance in the event that incorrect codes are posted online. Correctness of the final tally with respect to the published codes is proven by election officials in a manner that can be verified by any interested party. Thus, compromise of either ballot chain of custody or the software systems cannot undetectably affect election integrity. Scantegrity II has been implemented and tested in small elections in which ballots were scanned either at the polling place or centrally. Preparations for its use in a public sector election have commenced.

Tor is a popular privacy tool designed to help achieve online anonymity by anonymising web traffic. Employing cognitive walkthrough as the primary method, this paper evaluates four competing methods of deploying Tor clients, and a number of software tools designed to be used in conjunction with Tor: Vidalia, Privoxy, Torbutton, and FoxyProxy. It also considers the standalone anonymous browser TorPark. Our results show that none of the deployment options are fully satisfactory from a usability perspective, but we offer suggestions on how to incorporate the best aspects of each tool. As a framework for our usability evaluation, we also provide a set of guidelines for Tor usability compiled and adapted from existing work on usable security and human-computer interaction.