End-to-End Encrypted Group Messaging with Insider Security

Our society has become heavily dependent on electronic communication, and preserving the integrity of this communication has never been more important. Cryptography is a tool that can help to protect the security and privacy of these communications. Secure messaging protocols like OTR and Signal typically employ end-to-end encryption technology to mitigate some of the most egregious adversarial attacks, such as mass surveillance. However, the secure messaging protocols deployed today suffer from two major omissions: they do not natively support group conversations with three or more participants, and they do not fully defend against participants that behave maliciously. Secure messaging tools typically implement group conversations by establishing pairwise instances of a two-party secure messaging protocol, which limits their scalability and makes them vulnerable to insider attacks by malicious members of the group. Insiders can often perform attacks such as rendering the group permanently unusable, causing the state of the group to diverge for the other participants, or covertly remaining in the group after appearing to leave. It is increasingly important to prevent these insider attacks as group conversations become larger, because there are more potentially malicious participants. This dissertation introduces several new protocols that can be used to build modern communication tools with strong security and privacy properties, including resistance to insider attacks. Firstly, the dissertation addresses a weakness in current two-party secure messaging tools: malicious participants can leak portions of a conversation alongside cryptographic proof of authorship, undermining confidentiality. The dissertation introduces two new authenticated key exchange protocols, DAKEZ and XZDH, with deniability properties that can prevent this type of attack when integrated into a secure messaging protocol. DAKEZ provides strong deniability in interactive settings such as instant messaging, while XZDH provides deniability for non-interactive settings such as mobile messaging. These protocols are accompanied by composable security proofs. Secondly, the dissertation introduces Safehouse, a new protocol that can be used to implement secure group messaging tools for a wide range of applications. Safehouse solves the difficult cryptographic problems at the core of secure group messaging protocol design: it securely establishes and manages a shared encryption key for the group and ephemeral signing keys for the participants. These keys can be used to build chat rooms, team communication servers, video conferencing tools, and more. Safehouse enables a server to detect and reject protocol deviations, while still providing end-to-end encryption. This allows an honest server to completely prevent insider attacks launched by malicious participants. A malicious server can still perform a denial-of-service attack that renders the group unavailable or "forks" the group into subgroups that can never communicate again, but other attacks are prevented, even if the server colludes with a malicious participant. In particular, an adversary controlling the server and one or more participants cannot cause honest participants' group states to diverge (even in subtle ways) without also permanently preventing them from communicating, nor can the adversary arrange to covertly remain in the group after all of the malicious participants under its control are removed from the group. Safehouse supports non-interactive communication, dynamic group membership, mass membership changes, an invitation system, and secure property storage, while offering a variety of configurable security properties including forward secrecy, post-compromise security, long-term identity authentication, strong deniability, and anonymity preservation. The dissertation includes a complete proof-of-concept implementation of Safehouse and a sample application with a graphical client. Two sub-protocols of independent interest are also introduced: a new cryptographic primitive that can encrypt multiple private keys to several sets of recipients in a publicly verifiable and repeatable manner, and a round-efficient interactive group key exchange protocol that can instantiate multiple shared key pairs with a configurable knowledge relationship

Design and Verification of Specialised Security Goals for Protocol Families

Communication Protocols form a fundamental backbone of our modern information networks. These protocols provide a framework to describe how agents - Computers, Smartphones, RFID Tags and more - should structure their communication. As a result, the security of these protocols is implicitly trusted to protect our personal data. In 1997, Lowe presented ‘A Hierarchy of Authentication Specifications’, formalising a set of security requirements that might be expected of communication protocols. The value of these requirements is that they can be formally tested and verified against a protocol specification. This allows a user to have confidence that their communications are protected in ways that are uniformly defined and universally agreed upon. Since that time, the range of objectives and applications of real-world protocols has grown. Novel requirements - such as checking the physical distance between participants, or evolving trust assumptions of intermediate nodes on the network - mean that new attack vectors are found on a frequent basis. The challenge, then, is to define security goals which will guarantee security, even when the nature of these attacks is not known. In this thesis, a methodology for the design of security goals is created. It is used to define a collection of specialised security goals for protocols in multiple different families, by considering tailor-made models for these specific scenarios. For complex requirements, theorems are proved that simplify analysis, allowing the verification of security goals to be efficiently modelled in automated prover tools

Proceedings of the 23rd International Congress of Byzantine Studies : Round Tables

Following the 23rd International Congress of Byzantine Studies, the Organizing Committee decided to produce an online publication of Proceedings from the Round Tables. According to the official title of the congress, Byzantium - a World of Changes, AIEB together with the Organizing Committee, have decided to implement some changes to the concept of the Round Tables. The aim of these changes were to encourage discussion at the Round Tables by presenting preliminary papers at the website in advance. The idea was to introduce the topic and papers of the individual Round Tables that would be discussed, first between the participants, and then with the public present. Therefore, the conveners of the Round Tables were asked to create Round Tables with no more than 10 participants. They collected the papers, which were to be no longer than 18,000 characters in one of the official languages of the Congress and without footnotes or endnotes. Conveners provided a general statement on the goal of each roundtable and on the content of the papers. The present volume contains papers from 49 Round Tables carefully selected to cover a wide range of topics, developed over the last five years since the previous Congress. The topics show diversity within fields and subfields, ranging from history to art history, archeology, philosophy, literature, hagiography, and sigillography. The Round Tables displayed current advances in research, scholarly debates, as well as new methodologies and concerns germane to all aspects of international Byzantine studies. The papers presented in this volume were last sent to the congress organizers in the second week of August 2016 and represent the material that was on hand at that time and had been posted on the official website; no post-congress revisions have occurred. We present this volume in hope that it will be an initial step for further development of Round Tables into collections of articles and thematic books compiled and published following the Congress, in collaboration with other interested institutions and editors. With this volume, the organizers signal their appreciation of the efforts of more than 1600 participants who contributed, both to the Round Tables and to the Congress in general

A History of the Royal (Toronto) Conservatory of Music Piano Examinations, 1887-2015: Their Impact and Influence

Since its inception in 1887, the Royal Conservatory of Music has maintained its position as one of the largest and oldest community-based music schools and education centres in North America, with an integrated examination body and a comprehensive graded curriculum, influencing and shaping the Canadian musical landscape. For the past 130 years, the Conservatory has presented a wide-ranging art music repertoire for studying piano and offered a comprehensive system for assessing students progress through its Examinations, recently retitled as The Certificate Program. The Conservatorys internal examinations began in 1887, with the external examinations following in 1898. The latter preserved the format of the former and expanded through increasing the number of the examination centres across Canada for both financial and educational reasons. Despite varying opinions of professionals and amateurs on the efficacy and value of the piano examinations in particular from the beginning, this dissertation, using historical sources and interviews, argues that over the years the structure and content of the piano examinations, while innately conservative on the whole, have kept up with a changing demographic of students across the country, and either countered or taken on the many criticisms that surrounded them over the years despite geographical and financial challenges, and indeed competition from other institutions. Recently they have been hardy enough to enter the American market. Overall, the Conservatorys examination system has created a cultural asset ideal for a country such as Canada, providing, promoting, and disseminating both the branded curriculum and controlled assessment, which contributed to the development and improvement of music education rapidly and effectively. A distinctive part of the dissertation in addition to its detailed history is the interviews with current examiners and teachers, who face a whole new set of challenges and uncharted waters as technology offers new approaches to teaching and evaluation. In this ethnographic approach, their voices add a whole new dimension to the historical survey of the examinations system, arguing that despiteor perhaps because ofthe weight of tradition they still have much to offer

Choran community: The aesthetics of encounter in literary and photographic modernism

This dissertation examines novels, photographs, and phototexts by British and American artists published between the world wars in order to argue that these works re-envision community through a narrative aesthetic, which I term the choran moment, that communicates the possibility of genuinely empathetic understanding between self and other. My study of literary and photographic modernism is based upon these modern artists\u27 awareness of an ever-present, organic community allied in common knowledge of the interconnection among humanity offered through convergence with and respect for difference. These choran moments of correlation are key to the aesthetics and therefore the politics of modernist writers Virginia Woolf, Sylvia Townsend Warner, Nella Larsen, and Zora Neale Hurston, and photographers Gertrude Kasebier, James Van Der Zee, and Walker Evans. The artists I discuss share a common humanist concern for creating moments of wholeness in their work. Moreover, their evocations of choran moments lead to communal interconnectivity for both artist and audience. The longing to rediscover a choran moment allows modern artists and audiences to rediscover a wholeness of self---the first step toward finding intersubjectivity and, finally, interconnective community through art. The ethical encounter, enacted in the choran moment, invites both contemporary audiences and the present scholarly community to read modernism as an attempt at rebuilding interconnectivity. Through my intervention into established critical categories of Modernism, I identify a particular expression of the period by examining how a broad selection of writers and photographers engage with a common humanist concern for recreating community through their art. My assessment of a diverse set of writers and photographers enables literary critics to include all of these previously unconnected artists under a new critical category of modernist narratives of community in order to see the work of these modernists as interconnected, resonant, and mutually productive. We are the scholars who can benefit from these artists\u27 potentially transformative aesthetic of modernist choran moments and communal interconnectivity

Unfolding Musicking Archives At The Northwest Amazon

This dissertation proposes a decolonial revision of the archive consolidated by scholars, travelers and missionaries who previously sound recorded the Northwestern Amazon region, and introduces alternative ways of producing archival artifacts open to non-Indigenous and Indigenous perspectives and epistemologies alike. It studies the formation of sonic archives and points of listening that represented worlds of Indigenous expressivity in sound during the twentieth century in the Vaupés region, southern Colombia. This study focuses on Tukanoan musicking and specifically with the Cubeo Emi-Hehenewa clan, an Amazonian indigenous community living in a village called Camutí located at the Vaupés River Basin. This dissertation aims to reposition ethnomusicological practice in the Northwest Amazon as a collaborative and ethical research endeavor that can contribute new theoretical and methodological knowledge about and from the Vaupés region

3rd Annual Computer & Technology Law Institute

Materials from the 3rd Annual Computer & Technology Law Institute held by UK/CLE in March 2001

The European Pilgrimage Routes for promoting sustainable and quality tourism in rural areas

The International Conference the European Pilgrimage Routes for promoting sustainable and quality tourism in rural areas took place December 4 to 6, 2014 in Firenze (Italy) and was organized by the Department of Agricultural, Food and Forestry Systems – University of Florence in collaboration with the Tuscany Region, the Department for Life Quality Studies and Department of Agricultural Sciences – University of Bologna, the Italian Association of Agricultural Engineering and the European Association of the Francigena Way. The Conference involving 150 experts from 18 countries and was divided into five areas of discussion: conservation and evolution of the landscape along the routes; life quality and social impact; tourism and local development; sustainability in the rural areas; tools and methods for building a tourist attraction

The Newest Sappho: P. Sapph. Obbink and P. GC inv. 105, Frs. 1-4

In The Newest Sappho Anton Bierl and André Lardinois have edited 21 papers of world-renowned Sappho scholars dealing with the new papyrus fragments of poems by Sappho that were published in 2014. Readership: All interested in Classics, Greek and Roman literature, archaic lyric, song and performance culture, and anyone concerned with papyrology, archaic Greek culture, history, society, and religio