In computer forensics, digital evidence related to time is both important and complex. The rules of changes in time associated with digital evidence, such as files or folders, can be used to analyze certain user behaviors like data access, modification or transfer. However, the format and the rules in time information for user actions are quite different for different file systems, even for different versions of operating systems with the same file system. Some research on temporal analysis has already been done on NTFS and FAT file systems, while there are few resources that describe temporal analysis on the Hierarchical File System Plus (HFS+), the default file system in Apple computer. Moreover, removable devices like USB disks are used frequently; transferring files and folders between different devices with different file systems and operating systems happens more and more frequently, so the changes of times across different file systems are also crucial in digital forensics and investigations. In this research, the changes in time attributes of files and folders resulting from user actions on the HFS+ file system and across file systems are analyzed, and the rules of time are generated by inductive reasoning to help reconstruct crime scenes in the digital forensic investigation. Since inductive reasoning is not definitely true compared with deductive reasoning, experiments are performed to validate the rules. The usage of the rules is demonstrated by analyzing a case in details. The methods proposed here are efficient, practical and easy to put into practice in real scenarios. / published_or_final_version / Computer Science / Master / Master of Philosophy

This thesis explores regulatory mechanisms of managing the phenomenon of file sharing in the online environment without impeding key aspects of digital innovation, utilising a modified version of Lessig’s modalities of regulation to demonstrate significant asymmetries in various regulatory approaches. After laying the foundational legal context, the boundaries of future reform are identified as being limited by extra-jurisdictional considerations, and the regulatory direction of legal strategies to which these are related are linked with reliance on design-based regulation. The analysis of the plasticity of this regulatory form reveals fundamental vulnerabilities to the synthesis of hierarchical and architectural constraint, that illustrate the challenges faced by the regulator to date by countervailing forces. Examination of market-based influences suggests that the theoretical justification for the legal regulatory approach is not consistent with academic or policy research analysis, but the extant effect could impede openness and generational waves of innovation. A two-pronged investigation of entertainment industry-based market models indicates that the impact of file sharing could be mitigated through adaptation of the traditional model, or that informational decommodification could be harnessed through a suggested alternative model that embraces the flow of free copies. The latter model demonstrates how the interrelationships between extant network effects and sub-model externalities can be stimulated to maximise capture of revenue without recourse to disruption. The challenges of regulating community-based norms are further highlighted where the analysis submits that the prevalence of countervailing forces or push-back from the regulated act as an anti-constraint to hierarchical and design-based regulation, due to an asymmetry between legal, architectural and traditional market-based approaches, and effective control of the file sharing community. This thesis argues that file sharing can be regulated most efficaciously by addressing this asymmetry through alternative market-based strategies. This can be influenced through extending hierarchical regulation to offer alternative legal and norm-based models that complement, rather than disrupt, the community-based norms of file sharing.

This dissertation is an investigation into the practice of peer-to-peer file-sharing and the litigation campaign targeting individual file-sharers carried out by the Recording Industry Association of America (RIAA) from 2003 to 2008. The competing conceptualizations of social relations which motivate the conflict over peer-to-peer file-sharing are explored using a combination of Autonomist Marxist theory and structuration theory. Peer-to-peer file-sharing is framed as part of the social system of commoning stemming from the recent ascendancy of immaterial labor within that sector of the economy dedicated to the production and distribution of informational and cultural goods. The RIAA litigation campaign is framed as a reaction to the emergence of new forms of social relations which are seen by the content-producing industries as subversive of revenue streams premised on commodity exchange in informational and cultural goods. The history of the RIAA litigation campaign is presented in detail with careful attention given to those instances in which defendants and other interested parties fought back against RIAA legal actions. The acts of resistance within the legal arena affected the ultimate potential of the litigation campaign to control the spread of file-sharing activities. Subsequent legal campaigns which have been based on the RIAA litigation model are also examined. These later file-sharing cases have been met with similar forms of resistance which have likewise mitigated the impact of legal efforts to combat file-sharing. In addition, a survey of file-sharers is included in this research as part of an attempt to understand the relationship between legal actions targeting peer-to-peer systems and individual file-sharers and the technological and social development of peer-to-peer systems. This research argues that file-sharing litigation has proven ineffective in turning back the flood of file-sharing and may have increased the technological sophistication and community ties among file-sharers. In the end, the conflict over peer-to-peer file-sharing is cast as a manifestation of a larger dynamic of capitalist crisis as content-producing industries attempt to come to terms with the contradictory tendencies of immaterial labor and the production of common pools of digital resources. / text

I det här arbetet har författarna valt att fokusera på lagringssäkerhet ur synvinkelnhemmiljö. För att kunna ge målgruppen någon form av riktlinje definieras olika kravpå säkerhet och lagring från författarnas sida att utgå från vid diskussion och arbetetsupplägg. Arbetet inriktar sig på vad det finns för möjligheter för att kunna säkra uppde olika formerna av lagringsmöjligheter. Är det möjligt att göra? Vilka källor kanman förvänta sig att målgruppen använder för att lösa de här problemen? Genom attstudera tidigare forskning och göra omfattande dokumentstudier kommer författarnafram till vad som kan vara lämpligt att använda i en hemmiljö för säker fillagring.Arbetet mynnar ut i ett resultat med vad de olika lagringslösningarna och lagringstjänsternaklarar av för krav samt vad de klarar av för olika funktioner. Det finns ävenen form av rekommendation för användaren vad som kan vara en lämplig väg att gå,dock inte ett direkt svar på hur denna skall se ut. / The authors of this essay have chosen to focus on secure data storage from a homeenvironment standpoint. In order to give this target group something that resembles aguideline, several demands regarding security and storage will be defined. This willalso be used as a basis both for how the essay is approached and the discussion of it.The essay focuses on the possibilities when it comes to securing the varyingforms of storage solutions. Can it be done securely? In order to solve these problems,what sources are the target group most likely to use?Through study of earlier research, and extensive document studies, the authorsfind solutions regarding secure data storage that are feasible to use in a home environment.In the end, the essay will point out which of the defined demands thevarious storage solutions and services can handle, and which functions they can handle.There is also a recommendation for the reader regarding what is feasible andsuitable for use, though not a clear-cut answer saying which solution is the better;that’s still up to the reader herself to determine.

In this thesis a number of mathematical models are investigated with the aid of the modelling package Mathematica. Some of the models are of a mechanical nature and some of the models are laboratories that have been constructed for the purpose of assisting researchers in a particular field. In the early sections of the thesis mechanical models are investigated. After the equations of motion for the model have been presented, Mathematica is employed to generate solutions which are then used to drive animations of the model. The frames of the animations are graphical snapshots of the model in motion. Mathematica proves to be an ideal tool for this type of modelling since it combines algebraic, numeric and graphics capabilities on one platform. In the later sections of this thesis, Mathematica laboratories are created for investigating models in two different fields. The first laboratory is a collection of routines for performing Phase-Plane analysis of planar autonomous systems of ordinary differential equations. A model of a mathematical concept called a bifurcation is investigated and an animation of this mathematical event is produced. The second laboratory is intended to help researchers in the tomography field. A standard filtered back-projection algorithm for reconstructing images from their projections is implemented. In the final section of the thesis an indication of how the tomography laboratory could be used is presented. Wavelet theory is used to construct a new filter that could be used in filtered back-projection tomography. / Thesis (Ph.D.)-University of Natal, Durban, 1994.

In this thesis we analyse particular differential equations that arise in physical situations. This is achieved with the aid of the computer software package called Mathematica. We first describe the basic features of Mathematica highlighting its capabilities in performing calculations in mathematics. Then we consider a first order Newtonian equation representing the trajectory of a particle around a spherical object. Mathematica is used to solve the Newtonian equation both analytically and numerically. Graphical plots of the trajectories of the planetary bodies Mercury, Earth and Jupiter are presented. We attempt a similar analysis for the corresponding relativistic equation governing the orbits of gravitational objects. Only numerical results are possible in this case. We also perform a perturbative analysis of the relativistic equation and determine the amount of perihelion shift. The second equation considered is the Emden-Fowler equation of order two which arises in many physical problems, including certain inhomogeneous cosmological applications. The analytical features of this equation are investigated using Mathematica and the Lie analysis of differential equations. Different cases of the related autonomous form of the Emden-Fowler equation are investigated and graphically represented. Thereafter, we generate a number of profiles of the energy density and the pressure for a particular solution which demonstrates that a numerical approach for studying inhomogeneity, in cosmological models in general relativity, is feasible. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

A large number of personal cloud storage systems have emerged in recent years, such as Dropbox, iCloud, Google Drive etc. A common limitation of these system is that the users have to trust the cloud provider not to be malicious. Now we have a Unity block store, which can solve the problem and provide a secure and durable cloud-based block store. However, the base Unity system does not have the concept of file on top of its block device, thus the concurrent operations to different files can cause false sharing problem. In this thesis, we propose UnityFS, a file system built on top of the base Unity system. We design and implement the file system that maintains a mapping between files and a group of data blocks, such that the whole Unity system can support concurrent file operations to different files from multiple user devices in the personal cloud.

A large number of personal cloud storage systems have emerged in recent years, such as Dropbox, iCloud, Google Drive etc. A common limitation of these system is that the users have to trust the cloud provider not to be malicious. Now we have a Unity block store, which can solve the problem and provide a secure and durable cloud-based block store. However, the base Unity system does not have the concept of file on top of its block device, thus the concurrent operations to different files can cause false sharing problem. In this thesis, we propose UnityFS, a file system built on top of the base Unity system. We design and implement the file system that maintains a mapping between files and a group of data blocks, such that the whole Unity system can support concurrent file operations to different files from multiple user devices in the personal cloud.

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This thesis introduces Relative links or rlinks, which are directed labeled links from one file to another in a file system. Rlinks provide a clean way to build and share related-file information without creating additional files and directories. Rlinks form overlay graphs between files of a file system, thus providing useful alternate views of the file system. This thesis implements rlinks for the Linux kernel and modifies the storage structure of the Ext2 file system to store the rlinks.