Predictions to Ease Users' Effort in Scalable Sharing

Significant user effort is required to choose recipients of shared information, which grows as the scale of the number of potential or target recipients increases. It is our thesis that it is possible to develop new approaches to predict persistent named groups, ephemeral groups, and response times that will reduce user effort. We predict persistent named groups using the insight that implicit social graphs inferred from messages can be composed with existing prediction techniques designed for explicit social graphs, thereby demonstrating similar grouping patterns in email and communities. However, this approach still requires that users know when to generate such predictions. We predict group creation times based on the intuition that bursts of change in the social graph likely signal named group creation. While these recommendations can help create new groups, they do not update existing ones. We predict how existing named groups should evolve based on the insight that the growth rates of named groups and the underlying social graph will match. When appropriate named groups do not exist, it is useful to predict ephemeral groups of information recipients. We have developed an approach to make hierarchical recipient recommendations that groups the elements in a flat list of recommended recipients, and thus is composable with existing flat recipient-recommendation techniques. It is based on the insight that groups of recipients in past messages can be organized in a tree. To help users select among alternative sets of recipients, we have made predictions about the scale of response time of shared information, based on the insights that messages addressed to similar recipients or containing similar titles will yield similar response times. Our prediction approaches have been applied to three specific systems - email, Usenet and Stack Overflow - based on the insight that email recipients correspond to Stack Overflow tags and Usenet newsgroups. We evaluated these approaches with actual user data using new metrics for measuring the differences in scale between predicted and actual response times and measuring the costs of eliminating spurious named-group predictions, editing named-group recommendations for use in future messages, scanning and selecting hierarchical ephemeral group-recommendations, and manually entering recipients.Doctor of Philosoph

Toward practical and private online services

Today's common online services (social networks, media streaming, messaging, email, etc.) bring convenience. However, these services are susceptible to privacy leaks. Certainly, email snooping by rogue employees, email server hacks, and accidental disclosures of user ratings for movies are some sources of private information leakage. This dissertation investigates the following question: Can we build systems that (a) provide strong privacy guarantees to the users, (b) are consistent with existing commercial and policy regimes, and (c) are affordable? Satisfying all three requirements simultaneously is challenging, as providing strong privacy guarantees usually necessitates either sacrificing functionality, incurring high resource costs, or both. Indeed, there are powerful cryptographic protocols---private information retrieval (PIR), and secure two-party computation (2PC)---that provide strong guarantees but are orders of magnitude more expensive than their non-private counterparts. This dissertation takes these protocols as a starting point and then substantially reduces their costs by tailoring them using application-specific properties. It presents two systems, Popcorn and Pretzel, built on this design ethos. Popcorn is a Netflix-like media delivery system, that provably hides, even from the content distributor (for example, Netflix), which movie a user is watching. Popcorn tailors PIR protocols to the media domain. It amortizes the server-side overhead of PIR by batching requests from the large number of concurrent users retrieving content at any given time; and, it forms large batches without introducing playback delays by leveraging the properties of media streaming. Popcorn is consistent with the prevailing commercial regime (copyrights, etc.), and its per-request dollar cost is 3.87 times that of a non-private system. The other system described in this dissertation, Pretzel, is an email system that encrypts emails end-to-end between senders and intended recipients, but allows the email service provider to perform content-based spam filtering and targeted advertising. Pretzel refines a 2PC protocol. It reduces the resource consumption of the protocol by replacing the underlying encryption scheme with a more efficient one, applying a packing technique to conserve invocations of the encryption algorithm, and pruning the inputs to the protocol. Pretzel's costs, versus a legacy non-private implementation, are estimated to be up to 5.4 times for the email provider, with additional but modest client-side requirements. Popcorn and Pretzel have fundamental connections. For instance, the cryptographic protocols in both systems securely compute vector-matrix products. However, we observe that differences in the vector and matrix dimensions lead to different system designs. Ultimately, both systems represent a potentially appealing compromise: sacrifice some functionality to build in strong privacy properties at affordable costs.Computer Science

A location-based communication platform: integrating file sharing with interpersonal contact

Gemstone Team FLIP (File Lending in Proximity)Sharing on the Internet, even among computing devices in close proximity, is both inefficient and inconvenient. Online services and websites do not take advantage of easily obtainable geo-locational data that can improve sharing. We at Team FLIP have extended an existing mapping system called TerpNav with functionality that allows proximate users to interact and collaborate while sharing digital information. This study demonstrates both the feasibility of and demand for a more efficient and interactive method to exchange information among proximate networks of people

Visual analysis of e-mail communication to support digital forensics & e-discovery investigation in organisations

The main aim of the research is to design and develop interactive visual solutions to explore the information in E-mail communication data to support E-discovery compliance in an organisation. The solutions intent to assist the world of digital forensics and investigations, which will enable users/analysts to explore, identify/find/discover interesting communication behaviour and characterise information of interest. In this research, we designed & developed software prototypes through a structured process of abstraction, design and testing, by using a well-known methodology called Design Study Methodology (DSM). We describe our analysis/approach through examples applied within the context of a real-world application domain. Doing so is intended to explore and answer a series of research questions in ways that will improve the role of visualisation in Digital Forensics and E-discovery investigations. The work identified the knowledge gap, challenges, requirements and tasks in Digital Forensics and E-discovery involving the analysis of E-mail communication data from the unstructured interviews with the organisation domain experts and from the literature. We employed user-centered design (UCD) which involved iterative design process for 3 years and built several visual solutions based on the requirements and tasks. We evaluated the solutions by conducting an empirical study with the experts to understand E-discovery tasks, visual solutions and the interface that can help analyst, to investigate and navigate within communication data, to identify/find/discover various patterns, trends, anomalies and information that might be interesting/relevant to investigation. The solutions were deployed in the collaborator's E-mail platform

Cybersecurity of Digital Service Chains

This open access book presents the main scientific results from the H2020 GUARD project. The GUARD project aims at filling the current technological gap between software management paradigms and cybersecurity models, the latter still lacking orchestration and agility to effectively address the dynamicity of the former. This book provides a comprehensive review of the main concepts, architectures, algorithms, and non-technical aspects developed during three years of investigation; the description of the Smart Mobility use case developed at the end of the project gives a practical example of how the GUARD platform and related technologies can be deployed in practical scenarios. We expect the book to be interesting for the broad group of researchers, engineers, and professionals daily experiencing the inadequacy of outdated cybersecurity models for modern computing environments and cyber-physical systems