CacheCash: A Cryptocurrency-based Decentralized Content Delivery Network

Online content delivery has witnessed dramatic growth recently with traffic consuming over half of today’s Internet bandwidth. This escalating demand has motivated content publishers to move outside the traditional solutions of infrastructure-based content delivery networks (CDNs). Instead, many are employing peer-to-peer data transfers to reduce the service cost and avoid bandwidth over-provision to handle peak demands. Unfortunately, the open access work model of this paradigm, which allows anyone to join, introduces several design challenges related to security, efficiency, and peer availability. In this dissertation, we introduce CacheCash, a cryptocurrency-based decentralized content distribution network designed to address these challenges. CacheCash bypasses the centralized approach of CDN companies for one in which end users organically set up new caches in exchange for cryptocurrency tokens. Thus, it enables publishers to hire caches on an as-needed basis, without constraining these parties with long-term business commitments. To address the challenges encountered as the system evolved, we propose a number of protocols and techniques that represent basic building blocks of CacheCash’s design. First, motivated by the observation that conventional security assessment tools do not suit cryptocurrency-based systems, we propose ABC, a threat modeling framework capable of identifying attacker collusion and the new threat vectors that cryptocurrencies introduce. Second, we propose CAPnet, a defense mechanism against cache accounting attacks (i.e., a client pretends to be served allowing a colluding cache to collect rewards without doing any work). CAPnet features a bandwidth expenditure puzzle that clients must solve over the content before caches are given credit, which bounds the effectiveness of this collusion case. Third, to make it feasible to reward caches per data chunk served, we introduce MicroCash, a decentralized probabilistic micropayment scheme that reduces the overhead of processing these small payments. MicroCash implements several novel ideas that make micropayments more suitable for delay-sensitive applications, such as online content delivery. CacheCash combines the previous techniques to produce a novel service-payment exchange protocol that secures the content distribution process. This protocol utilizes gradual content disclosure and partial payment collection to encourage the honest collaborative work between participants. We present a detailed game theoretic analysis showing how to exploit rational financial incentives to address several security threats. This is in addition to various performance optimization mechanisms that promote system efficiency and scalability. Lastly, we evaluate system performance and show that modest machines can serve/retrieve content at a high bitrate with minimal overhead

Privacy in the Genomic Era

Genome sequencing technology has advanced at a rapid pace and it is now possible to generate highly-detailed genotypes inexpensively. The collection and analysis of such data has the potential to support various applications, including personalized medical services. While the benefits of the genomics revolution are trumpeted by the biomedical community, the increased availability of such data has major implications for personal privacy; notably because the genome has certain essential features, which include (but are not limited to) (i) an association with traits and certain diseases, (ii) identification capability (e.g., forensics), and (iii) revelation of family relationships. Moreover, direct-to-consumer DNA testing increases the likelihood that genome data will be made available in less regulated environments, such as the Internet and for-profit companies. The problem of genome data privacy thus resides at the crossroads of computer science, medicine, and public policy. While the computer scientists have addressed data privacy for various data types, there has been less attention dedicated to genomic data. Thus, the goal of this paper is to provide a systematization of knowledge for the computer science community. In doing so, we address some of the (sometimes erroneous) beliefs of this field and we report on a survey we conducted about genome data privacy with biomedical specialists. Then, after characterizing the genome privacy problem, we review the state-of-the-art regarding privacy attacks on genomic data and strategies for mitigating such attacks, as well as contextualizing these attacks from the perspective of medicine and public policy. This paper concludes with an enumeration of the challenges for genome data privacy and presents a framework to systematize the analysis of threats and the design of countermeasures as the field moves forward

Can I ask...? An alcohol and drug clinician’s guide to addressing family and domestic violence

There is a growing impetus for a more comprehensive approach to understanding and addressing family and domestic violence (FDV) across the broader welfare system. This includes an increased focus on prevention and the interrelationship between sectors such as alcohol and other drugs (AOD), child and family welfare, child protection and FDV. This change is reflected in a number of national policies related to the protection and wellbeing of children and the support provided to their families. This resource explores the relationship between AOD and FDV, with a focus on identifying how the AOD sector can better support clients who have co-occurring AOD and FDV issues, and minimise associated harms experienced by their children. Authors: Michael White, Ann Roche, Roger Nicholas, Caroline Long, Stefan Gruenert, Samantha Battams. Produced by the National Centre for Education and Training on Addiction (NCETA) and Odyssey House Victoria (OHV)

Methodologies for Evaluating Security Risk and Safeguards for HEU to LEU conversion of a Miniature Neutron Source Reactor (MNSR) using SCALE and ORIGEN

Rising global opinions on security of vulnerable nuclear materials at research reactor facilities against misuse and acquisition by terrorist or violent groups has led to the implementation of the enrichment reduction program focused at reducing enrichment in fuel from about 90% to less than 20%. This program has provided an extraordinary prospect of improving international security to counter the fears of direct use of HEU materials acquired from these facilities for non-peaceful purposes. Ongoing efforts by the United States Department of Energy (DOE) through the Reduced Enrichment in Test and Research Reactors (RETRR) and the International Atomic Energy Agency (IAEA) supports countries to develop and adapt better technical capabilities targeted towards this program. This research enumerated and compared the amount of weapon-usable materials that the reactor produced in both the HEU and LEU fuel at varying time intervals of operation from a simulated neutronic model of the Nigeria Research Reactor (NIRR-1) developed with SCALE and ORIGEN code. Consequently, result obtained showed that weapon-usable 239Pu balance for LEU fuel compared to HEU increased linearly about 10-fold as the number of days of operation increases. This 239Pu growth was strongly considered for the ongoing conversion of Miniature Neutron Source Reactors (MNSR) as a case study because of the concern that out of the nine licensed prototype MNSR worldwide, four are in China, the origin of the design but the other five are in Ghana, Iran, Nigeria Pakistan and Syria. These five countries have well organized terrorist or violent groups that could potentially acquire nuclear materials or sabotage these facilities to disperse radiological materials which should be a call to more action for more security as well as international safeguards and accounting for nuclear materials. Additionally, based on the outcome of this simulation, as well as the vulnerability assessment carried out that included seeming capabilities of terrorist groups operating near the NIRR-1 facility, security risk and safeguards were evaluated, and suggestions were made on security risk of the increasing quantity of weapon-usable 239Pu isotope