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In scenarios where an individual wishes to leak confidential information to an unauthorized party, he may do so in a public or an anonymous way. When acting publicly a leaker exposes his identity, whereas acting anonymously a leaker can introduce doubts about the information’s authenticity. Current solutions assume anonymity from everyone except a trusted third party or rely on the leaker possessing prior cryptographic keys, both of which are inadequate assumptions in real-world secret leaking scenarios. In this research we present a system called the attested drop protocol which provides confidentiality for the leaker, while still allowing leaked documents to have their origins verified. The protocol relies on identities associated with common communication mediums, and seeks to avoid having the leaker carry out sophisticated cryptographic operations. We also present two constructions of the general protocol, where each is designed to protect against different forms of adversarial surveillance. We use ceremony analysis and other techniques from the provable security paradigm to formally describe and evaluate security goals for both constructions. / Thesis / Master of Science (MSc) / Whistleblowing is an activity where an individual leaks some secrets about an organization to an unauthorized entity, often for moral or regulatory reasons. When doing so, the whistleblower is faced with the choice of acting publicly, and risking retribution or acting anonymously and risking not being believed. We have designed a protocol called the attested drop protocol, which protects the identity of the whistleblower, while allowing the unauthorized entity to have a means of verifying that the leak came from the organization. This protocol makes use of preexisting identities associated with a communication medium, such as emails, to avoid using cryptographic primitives that are impractical.

Thanks to the rapid development of variable production patterns of industries, many kinds of chemicals are used. But the chemicals usually come with dangers of causing fires, explosions, and harming people. In the past decade in Taiwan, these chemicals caused many serious industrial disasters. They happened not only in conventional industries but also in semiconductor and chemical industries. And most of them happened due to the leaking of flammable or toxic gases. In the situation of the outbreak of fires, explosions may occur, and they will generally bring about heat radiation, explosive pressure, and energy releasing. And all of these often harm the workers and the environment, and also bring great loss for the factories. In order to prevent the disasters, except for improving the protection and safety equipment, it¡¦s more important to realize how to use effective ways to reduce them. If the gas pipes pass through a densely populated area, when some toxic gas leaks, it will cause fatal dangers which result from the mixing of gas diffusion and air, the flow process of the mixture, concentration of CH4, and temperature distribution, or explosions. After that, some toxic gas with poisonous substances will be released, and it will turn out to be horrible consequences that are beyond our imagination. So it¡¦s really important to do research on gas leaking and gas diffusion. If gas-leaking simulation is applied on the analysis of the leaking of flammable gas and gas diffusion, it¡¦s much more possible to protect the workers from being hurt, keep public safety, and reduce the loss on the wealth of the society. The thesis focuses on building various hazard patterns of gas leaking, gas explosions, and chemicals, etc. From all of these, the initial conditions and the degrees of dangers will be revealed. In the thesis, numerical simulation is used to analyze the density, pressure, speed of the leaking gas and all the distributions in the flow field. The major analysis is about the effects of parameter and the display of concentration distribution, and hazard range.

Due to national environmental goals, 191 closed landfills were inventoried according to a national methodology for inventory of polluted areas. The inventory took place in thirteen of the municipalities in the region of Västerbotten during the summer of 2013. 159 of the landfills were classified to risk class 3 on a scale of 4. Landfills in this category consist of diverse nature, ranging from adequate coverage but poor placement, to insufficient coverage and visible leakage, but without urgent risk. The purpose of this report was to follow up on the inventory. It resulted in identifying and prioritizing the actions required and a general plan of action for the landfills in the region. The focus was mainly on landfills in class 3, but those in risk class 2 are also included. This report was based mostly on forms for the closed landfills and a survey aimed at regional administrations. The result showed that the most common actions required were clean up, coverage, investigation of leakage and information about the unsuitability of depositing waste, including yard waste, at a closed landfill. A status division of the landfills in class 3 was determined, where the landfills that required actions were assigned the statuses +, 0 or -. Criteria for + includes proximity to vulnerable nature, risk for contamination of drinking water, poor coverage, or visible leakage. The landfills in class 2 should be prioritized for further actions, and after that those in risk class 3 with the + status.

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Telephony plays a fundamental role in our society. It enables remote parties to interact and express themselves over great distances. The telephone as a means of communicating has become part of every day life. Organisations and industry are now looking at Voice over IP (VoIP) technologies. They want to take advantage of new and previously unavailable voice services. Various interested parties are seeking to leverage the emerging VoIP technology for more flexible and efficient communication between staff, clients and partners. <o>VoIP is a recent innovation enabled by Next Generation Network (NGN). It provides and enables means of communication over a digital network, specifically the Internet. VoIP is gaining wide spread adoption and will ultimately replace traditional telephony. The result of this trend is a ubiquitous, global and digital communication infrastructure. VoIP, however, still faces many challenges. It is not yet as reliable and dependable as the current Public Switched Telephone Network (PSTN). The employed communication protocols are immature with many security flaws and weaknesses. Session Initiation Protocol (SIP), a popular VoIP protocol does not sufficiently protect a users privacy. A user’s information is neither encrypted nor secured when calling a remote party. There is a lack of control over the information included in the SIP messages. Our specific concern is that private and sensitive information is exchanged over the public internet. This dissertation concerns itself with the communication path chosen by SIP when establishing a session with a remote party. In SIP, VoIP calls are established over unknown and untrusted intermediaries to reach the desired party. We analyse the SIP headers to determine the information leakage at each chosen intermediary. Our concerns for possible breach of privacy when using SIP were confirmed by the findings. A user’s privacy can be compromised through the extraction of explicit private details reflected in SIP headers. It is further possible to profile the user and determine communication habits from implicit time, location and device information. Our research proposes enhancements to SIP. Each intermediary must digitally sign over the SIP headers ensuring the communication path was not be altered. These signatures are added sequentially creating a chain of certified intermediaries. Our enhancements to SIP do not seek to encrypt the headers, but to use these intermediary signatures to reduce the risk of information leakage. We created a model of our proposed enhancements for attaching signatures at each intermediary. The model also provides a means of identifying unknown or malicious intermediaries prior to establishing a SIP session. Finally, the model was specified in Z notation. The Z specification language was well suited to accurately and precisely represent our model. This formal notation was adopted to specify the types, states and model behaviour. The specification was validated using the Z type-checker ZTC. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Computer Science / unrestricted

The unauthorised disclosure of official information has caused embarrassment to successive governments regardless of political affiliation. At times, the disclosure of highly important documents pertaining to national security has reportedly caused immeasurable harm to the defence of the realm and damaged international cooperation. The protection of national security may however be used as a shield behind which malpractice can occur. Use of the Official Secrets Acts to prosecute Crown Servants for the unauthorised disclosure of information damaging to the reputation of government has proved controversial. Crown servants operate in an environment whereby a relationship of trust and loyalty is paramount to the running of government in a democratic society. Crown servants, however, remain in a unique position to witness acts of malpractice or maladministration. When other checks and balances fail, the Crown servant is faced with the unenviable prospect of allowing the malpractice to continue or to blow the whistle. This thesis provides an assessment of the existing officially prescribed mechanisms for Crown servants to blow the whistle and the position of the Crown servant as a journalistic source. It considers Crown servants in the Civil Service and is extended to provide two distinct case studies of servants in the UK intelligence community and members of the UK armed forces. This thesis critically evaluates the available whistleblower procedures alongside the current mechanisms used to hold the government and its departments to account, concluding that there are significant gaps in the current processes. Comparative analysis of other jurisdictions is used to bolster understanding with the objective of providing a number of key recommendations to provide strong, viable, alternatives to unauthorised disclosures.

A recent shallow earthquake in the Corinth Gulf, Greece (Mw 5.3) generated unusual long-period waves (periods > 5 seconds) between the P- and S-wave arrival. The 5-second period, being significantly longer than the source duration, indicates a structural effect. Observed seismograms were examined by methods of the frequency-time analysis. Disper- sion curves of the fast long-period (FLP) waves indicated group velocities ranging from 3 to 5.5 km/s for periods between 4 and 10 s, respectively, with large variations among the stations. The generalized dispersion curve splits into two major strips, probably related to lateral variations of the crustal structure. Forward simulations for several existing crustal models were made. A few partially successful models served for a sensitivity study, which showed that the FLP wave seemed to be mainly due to the low-velocity layers in the uppermost 4 kilometers of the crust. Finally the shallow crustal structure was retrieved by inverting observed seismograms by Neighborhood algorithm. The inversion confirmed that the FLP wave in seismograms at more than a single station cannot be explained with a 1-D crustal model. The path-dependent models provided a partial explanation for the strips revealed in the experimental dispersion curves. An alternative explanation is by...

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