How to Bootstrap Anonymous Communication

We ask whether it is possible to anonymously communicate a large amount of data using only public (non-anonymous) communication together with a small anonymous channel. We think this is a central question in the theory of anonymous communication and to the best of our knowledge this is the first formal study in this direction. To solve this problem, we introduce the concept of anonymous steganography: think of a leaker Lea who wants to leak a large document to Joe the journalist. Using anonymous steganography Lea can embed this document in innocent looking communication on some popular website (such as cat videos on YouTube or funny memes on 9GAG). Then Lea provides Joe with a short key $k$ which, when applied to the entire website, recovers the document while hiding the identity of Lea among the large number of users of the website. Our contributions include: - Introducing and formally defining anonymous steganography, - A construction showing that anonymous steganography is possible (which uses recent results in circuits obfuscation), - A lower bound on the number of bits which are needed to bootstrap anonymous communication.Comment: 15 page

Languages, ethnicity, and education in London

For the first time in 2008 the Annual School Census (ASC) required all schools to provide pupil information on the language spoken at home. Our analysis focuses on children attending state schools in London. Over 300 languages are spoken by London pupils, around 60% of London pupils are English speakers however, there are over 40 languages spoken by more than 1,000 pupils. Bengali, Urdu and Somali are the top three languages spoken in London, other than English. We show that English has a `doughnut' shaped geographical distribution in London, being the predominant language in most of Outer London. Languages other than English are more common in Inner London. Most minority languages, such as Bengali, Urdu and Turkish, have one, two or three main clusters, reflected settled immigrant communities. However others, notably Somali, are widely dispersed. This has implications for service provision. Some of the ethnic categories that are widely used in analysis of Census data hide substantial linguistic diversity, particularly `Black African' and `White Other.' Within London, where these groups are numerous, language data provides a valuable disaggregation of these heterogeneous groups. Our work suggests that language spoken provides a means to better understand the relationship between ethnicity and educational performance.Languages, London, ethnicity, educational performance

Oblivion: Mitigating Privacy Leaks by Controlling the Discoverability of Online Information

Search engines are the prevalently used tools to collect information about individuals on the Internet. Search results typically comprise a variety of sources that contain personal information -- either intentionally released by the person herself, or unintentionally leaked or published by third parties, often with detrimental effects on the individual's privacy. To grant individuals the ability to regain control over their disseminated personal information, the European Court of Justice recently ruled that EU citizens have a right to be forgotten in the sense that indexing systems, must offer them technical means to request removal of links from search results that point to sources violating their data protection rights. As of now, these technical means consist of a web form that requires a user to manually identify all relevant links upfront and to insert them into the web form, followed by a manual evaluation by employees of the indexing system to assess if the request is eligible and lawful. We propose a universal framework Oblivion to support the automation of the right to be forgotten in a scalable, provable and privacy-preserving manner. First, Oblivion enables a user to automatically find and tag her disseminated personal information using natural language processing and image recognition techniques and file a request in a privacy-preserving manner. Second, Oblivion provides indexing systems with an automated and provable eligibility mechanism, asserting that the author of a request is indeed affected by an online resource. The automated ligibility proof ensures censorship-resistance so that only legitimately affected individuals can request the removal of corresponding links from search results. We have conducted comprehensive evaluations, showing that Oblivion is capable of handling 278 removal requests per second, and is hence suitable for large-scale deployment

An introduction to crowdsourcing for language and multimedia technology research

Language and multimedia technology research often relies on large manually constructed datasets for training or evaluation of algorithms and systems. Constructing these datasets is often expensive with significant challenges in terms of recruitment of personnel to carry out the work. Crowdsourcing methods using scalable pools of workers available on-demand offers a flexible means of rapid low-cost construction of many of these datasets to support existing research requirements and potentially promote new research initiatives that would otherwise not be possible

A CAPTCHA model based on visual psychophysics: Using the brain to distinguish between human users and automated computer bots

Demand for the use of online services such as free emails, social networks, and online polling is increasing at an exponential rate. Due to this, online service providers and retailers feel pressurised to satisfy the multitude of end-user expectations. Meanwhile, automated computer robots (known as “bots”) are targeting online retailers and service providers by acting as human users and providing false information in order to abuse their service provisioning. CAPTCHA is a set of challenge/response protocol, which was introduced to protect online retailers and service providers from misuse and automated computer attacks. Text-based CAPTCHAs are the most popular form, and are used by most online service providers to differentiate between the human users and bots. However, the vast majority of text-based CAPTCHAs have been broken using the Optical Character Recognition (OCR) techniques and thus, reinforces the need for developing a secure and robust CAPTCHA model. Security and usability are the two fundamental issues that pose a trade-off in the design of a CAPTCHA; a hard CAPTCHA model could also be difficult for human users to resolve, which affects its usability, and vice versa. The model developed in this study uses the unsurpassed abilities of the Human Visual System (HVS) to superimpose and integrate complex information presented in individual frames, using the mechanism of trans-saccadic memory. In this context, the model integrates in its design the concept of persistence of vision, which enables humans to see the world in a continuous fashion. Preliminary results from the proposed model based on this technique are encouraging. To ensure the usability of the proposed CAPTCHA model, we set the threshold for the ORO parameter at 40%. This ensured that our CAPTCHA strings would be recognised by human observers at a rate of over 99% (or as close to 100% as is realistic). In turn, when examining the robustness of our VICAP model to computer programme attacks, we can observe that for the traditional case of OCR recognition, based on a single-frame scenario, the Computer Recognition Success Rate (CRSR) was about 0%, while in the case of a multi-frame scenario, the CRSR could increase to up to 50%

ISO 14063 : driving forces and new benefits in environmental communication

The enterprises of today are beginning to realize that environmental issues are a important part of their activity. Companies and organizations are expected to a greater extent communicate their environmental work to the world surrounding them in a trustworthy and structured way. Lack of information or information that is incorrect may bring farreaching consequences. Communication is mentioned in several of the ISO 14001-standards. But what is missing is a guideline how companies should act to create and be sure of the quality of the data that can be used in the environmental communication. There are a lot of report standards but little is said about how the company should conduct their environmental communication. The companies have, many times, not identified their stakeholders to create a picture of what the stakeholders demand. Furthermore, the dialogue with their stakeholders is occurring without planning or any preparation. In the year of 2000, a new ISO standard was created, which was named ISO 14063. It provides a guideline for environmental communication. The aim of the master's thesis is to examine in what way the new standard, ISO 14063, can guidance in their environmental communication efforts. Questions of special interest are; is the standard needed? Can the new standard give companies any new benefits such as economic profit or reduced costs? Will companies be able to use it in their daily work? Can the standard help companies to improve their dialogue with the surrounding world? A selection of ten companies in five different branches has been done for the interviews about environmental communication. The questions are asked about the content of the ISO 14063 standard, but they do not go in to it directly except for one question. Because none of the companies have had the time to read the standard or worked with it yet. One interview has been conducted in each company, except for some cases when we had to complement with another contact in the same company. Our study led to the following conclusions: One driving force for the standard is that it is a guideline and not a standard of demands. Another driving force is that the companies need to improve their environmental communication to reach out with the right message to their stakeholders. We consider the standard as needed, because the companies express an interest for it and they lack in their identification of strategic stakeholders. The future benefits for the companies lie in that the companies have a need to improve their environmental communication to receive economic profits. The companies can reduce their costs by being aware and honest in their communication, which avoids misunderstandings. We believe that the standard will be used by the companies in their daily work without any great costs. We also believe that the standard can be a good help for the companies to improve their dialogue with the surrounding world thanks to the fact that it is a guideline. The companies can use the parts of the standard that is necessary in different situations. A successful creation of a sustainable environment requires the interplay between markets. Profitability and environment must be balanced, and the condition for this balance is a good communication.Dagens företag börjar i allt större utsträckning inse att miljö är en viktig del i deras verksamhet. Företag och organisationer förväntas i allt högre utsträckning kommunicera sitt miljöarbete till omvärlden på ett trovärdigt och strukturerat sätt. Brist på information eller information som är felaktig kan få långtgående konsekvenser för en organisation. Kommunikation berörs i flera av standarderna i ISO 14001-serien. Det saknas däremot en vägledning hur företag bör gå tillväga för att ta fram och kvalitetssäkra data som senare kan användas i miljökommunikationen. Det finns många olika rapportstandarder, men ingen som konkret handlar om hur företaget ska gå tillväga i sin miljökommunikation. Företagen har många gånger inte identifierat sina intressenter och skapat sig en bild av vad dessa efterfrågar. Dessutom sker många gånger företagens dialog med intressenterna oplanerat utan några förberedelser. År 2000 togs en ny ISO-standard fram, vilken kom att kallas ISO 14063 och behandlar ämnet miljökommunikation. Syftet med examensarbetet är att undersöka på vilket sätt standarden ISO 14063 kan ge företagen nya drivkrafter. Frågor av speciellt intresse är då; Behövs standarden? Kan den nya standarden ge företag någon ny nytta som ekonomiska vinster eller minskade kostnader? Kommer den att kunna användas av företagen i deras dagliga arbete? Kan standarden hjälpa företaget att förbättra sin dialog med omvärlden? Ett urval på tio företag i fem olika branscher gjordes för intervjuerna kring miljökommunikation. Frågorna är ställda kring upplägget av ISO 14063-standarden men går inte in direkt på den, utom i en fråga, eftersom nästan inget företag har hunnit sätt sig in i standarden, eller arbetat efter den ännu. Det har gjorts en intervju i varje företag utom i ett par fall då det behövts komplettera med en annan kontaktperson inom samma företag. Vår studie ledde fram till följande slutsatser: En drivkraft för standarden ligger i att den är en guideline och inte en kravstandard. En annan drivkraft är att företagen behöver förbättra sin miljökommunikation för att nå ut med rätt budskap till sina intressenter. Vi anser att standarden behövs, eftersom företagen uttrycker ett intresse för den och brister i sin identifiering av intressenter. Den framtida nyttan för företagen ligger i att företagen har ett behov av att förbättra sin miljökommunikation för att bl a öka sina ekonomiska vinster. Företagen kan minska sina kostnader genom att de är medvetna och ärliga i sin kommunikation, vilket gör att missförstånd undviks. Vi tror att standarden kommer att kunna användas av företagen i deras dagliga arbete utan att detta medför några större merkostnader. Vi tror även att standarden kan vara till god hjälp för företagen att förbättra sin dialog med omvärlden tack vare att det är en guideline. Företagen kan använda de delar av standarden som känns relevanta i olika situationer. För att vi skall lyckas skapa ett hållbart samhälle så måste samspelet mellan marknad, lönsamhet och miljö fungera, grundbultarna i detta är då en god kommunikation

Experimentos físicos de barragens de terra homogênea sujeitas ao galgamento

Barragens são estruturas na qual sua construção sempre esteve associada ao benefício que trazem para a sociedade, permitindo o desenvolvimento de atividades essenciais em decorrência de seus múltiplos. Entretanto, essas estruturas estão sujeitas a falhas que podem levar ao seu rompimento. Excepcionalmente, no ano de 2020 foram reportadas 44 rupturas de barragens pela ANA que tiveram, em grande parte, como causa o galgamento, associado a eventos de intensa precipitação. Em sua maioria, esses acidentes ocorreram em barragens de terra. Assim, este trabalho possui como objetivo analisar o efeito de diferentes vazões e tempos de enchimento do reservatório no rompimento por galgamento em barragens de terra homogêneas, utilizando modelagem física. Neste viés, foi construído um modelo reduzido de uma barragem de terra hipotética em que foram realizadas três simulações físicas no qual foi simulado o enchimento rápido e lento do reservatório. O enchimento do reservatório ocorreu em duas etapas (que consistiu em divisões de alturas de níveis da barragem). Está divisão foi realizada com o objetivo de simular um reservatório que já estava operando com nível d’água máximo na borda livre e depois recebeu um incremento de vazão até a sua ruptura. Os resultados foram coletados através de iPad, cronômetro, medidor de vazão eletromagnético e um medidor de nível instalado no final do canal que registraram, respectivamente, fotos e vídeos, tempo dos processos, vazão e volume injetados e o nível de água correspondente a onda de ruptura ao longo do tempo. Os principais resultados foram em relação a percolação no maciço e as suas deformações, a mensuração da vazão na qual a estrutura rompeu, o tempo que a barragem levou para romper, a origem e evolução da brecha de ruptura, o hidrograma de ruptura e o balanço de massa do material que ficou retido no barramento e o material que foi carregado pela onda de ruptura. Conclui-se que as diferentes distribuições temporais do enchimento do reservatório afetam o rompimento de barragens de terra, principalmente em relação a saturação do maciço. Não é apenas um parâmetro de forma isolada o único responsável pela ruptura e sim um conjunto de parâmetros como grau de compactação, percolação do maciço e origem da brecha. A forma como é realizado o enchimento do reservatório impacta na forma como o maciço vai se comportar e isso contribui diretamente para a formação da brecha. A evolução da brecha de ruptura sofreu significativas deformações nos segundos iniciais após a ruptura.Dams are structures in which their construction has always been associated with the benefit they bring to society, allowing the development of essential activities as a result of their multiples. However, these structures are subject to failures that can lead to their rupture. Exceptionally, in 2020, 44 dam failures were reported by the ANA, which were largely due to overtopping, associated with events of intense tension. Most of these accidents occurred in earth dams. Thus, this work aims to analyze the effect of different outflows and reservoir filling times on failure by overtopping in transparent earth dams, using physical modeling. In this case, a limited model of a hypothetical earth dam was built in which three physical simulations were performed in which the fast and slow filling of the reservoir was simulated. Filling of the reservoir in two stages (which consists of divisions of heights of dam levels). This mission was carried out with the objective of simulating a reservoir that was already operating with maximum water level at the free edge and then received an increase in flow until its rupture. The results were collected using an iPad, a stopwatch, an electromagnetic flow meter and a level meter installed at the end of the channel, which recorded, respectively, photos and videos, process times, injected flow and volume and the water level corresponding to the wave of rupture over time. The main results were in relation to the percolation in the massif and its deformations, the measurement of the flow in which the structure broke, the time that the dam took to break, the origin and evolution of the breach, the hydrograph of rupture and the balance mass of the material that was retained in the busbar and the material that was carried by the rupture wave. It is concluded that there are different temporary distributions of reservoir filling and rupture of earth dams, mainly in relation to the saturation of the massif. It is not just an isolated shape parameter that is solely responsible for the failure, but a set of intervals such as the degree of compaction, percolation of the massif and the origin of the breach. The way in which the reservoir is filled impacts the way the massif will behave and this directly contributes to the formation of the breach. The evolution of the rupture breach suffered serious deformations in the initial seconds after the rupture

Crowdsourcing and Scholarly Culture: Understanding Expertise in an Age of Popularism

The increasing volume of digital material available to the humanities creates clear potential for crowdsourcing. However, tasks in the digital humanities typically do not satisfy the standard requirement for decomposition into microtasks each of which must require little expertise on behalf of the worker and little context of the broader task. Instead, humanities tasks require scholarly knowledge to perform and even where sub-tasks can be extracted, these often involve broader context of the document or corpus from which they are extracted. That is the tasks are macrotasks, resisting simple decomposition. Building on a case study from musicology, the In Concert project, we will explore both the barriers to crowdsourcing in the creation of digital corpora and also examples where elements of automatic processing or less-expert work are possible in a broader matrix that also includes expert microtasks and macrotasks. Crucially we will see that the macrotask–microtask distinction is nuanced: it is often possible to create a partial decomposition into less-expert microtasks with residual expert macrotasks, and crucially do this in ways that preserve scholarly values