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京都大学 / 新制・課程博士 / 博士(情報学) / 甲第24731号 / 情博第819号 / 新制||情||138(附属図書館) / 京都大学大学院情報学研究科社会情報学専攻 / (主査)教授 神田 崇行, 教授 吉川 正俊, 教授 梅野 健, TIBOUCHI Mehdi(NTT社会情報研究所) / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

In the coming millennium, the establishment of virtual enterprises will become increasingly common. In the engineering sector, global competition will require corporations to create agile partnerships to use each other’s engineering resources in mutually profitable ways. The Internet offers a medium for accessing such resources in a globally networked environment. However, remote access of resources require a secure and mutually trustable environment, which is lacking in the basic infrastructure on which the Internet is based. Fortunately, efforts are under way to provide the required security services on the Internet. This thesis presents a model for making distributed engineering software tools accessible via the Internet. The model consists of an extensible clientserver system interfaced with the engineering software tool on the server-side. The system features robust security support based on public-key and symmetric cryptography. The system has been demonstrated by providing Web-based access to a .STL file repair program through a Java-enabled Web browser. / Master of Science

Cryptographic hash functions are used extensively in information security, most notably in digital authentication and data integrity verification. Their performance is an important factor of the overall performance of a secure system. In 2005, some groups of cryptanalysts were making increasingly successful attacks and exploits on the cryptographic hash function, SHA-1, the most widely used hash function of the secure hashing algorithm family. Although these attacks do not work on SHA-2, the next in the series of the secure hashing algorithm family, the National Institute of Standards and Technology still believes that it is necessary to hold a competition to select a new algorithm to be added to the current secure hashing algorithm family. The new algorithm will be chosen through a public competition. The entries will be evaluated with different kinds of criteria, such as security, performance and implementation characteristics. These criteria will not only cover the domain of software, but the domain of hardware as well. This is the motivation of this thesis. This thesis will describe the experiments and measurements done to evaluate the SHA-3 cryptographic hash function candidates' performance on both ASIC and FPGA devices. The methodology, metrics, implementation details, and the framework of the experiments will be described. The results on both hardware devices will be shown and possible future directions will be discussed. / Master of Science

Software protection is increasingly necessary for a number of applications, ranging from commercial systems and digital content distributors, to military systems exposed in the field of operations. As computing devices become more pervasive, and software more complex, insufficiencies with current software protection mechanisms have arisen. Software--only and data--only protection systems have resulted in broken systems that are vulnerable to loss of software confidentiality and integrity. A growing number of researchers have suggested that hardware encryption mechanisms be employed to enforce software protection. Although there are several competing architectures, few offer the necessary protection while remaining compatible with modern computing systems and models. The Virginia Tech Secure Software Platform is the first architecture to achieve both increased protection and usability. This thesis presents the design and implementation of a fast, flexible Encryption Management Unit (EMU) for Virginia Tech Secure Software and compatible platforms. The design is capable of providing decryption of program instructions residing in page--sized sections of memory, without modification to the core processor. The effect of the EMU is modeled with varying application types and system loads. Lastly, a benchmark designed to measure actual performance was created to measure the actual performance of the EMU and validate the models. / Master of Science

Approved for public release; distribution is unlimited / Public key cryptography and the infrastructure that has been designed to successfully implement it: Public Key Infrastructure (PKI) is a very promising computer security technology. As a significant enhancement to this infrastructure, the DoD is now issuing smart card tokens, in the form of the Common Access Card (CAC), to its service members. This card is a relatively complex cryptographic device that contains its user's private keys, digital certificates, and other personal/administrative information. Service personnel are being issued these cards with little or no training regarding what they are or how they function. Such an omission detracts from the infrastructure's overall security. This thesis presents an introductory-level description of public key cryptography and its supporting infrastructure (PKI). The thesis then goes on to develop a web-based training tool that could provide all DoD CAC holders with the rudimentary knowledge of how their CAC fits into the broader infrastructure. The training tool will require no instructor, and will present a validation test to each user. DoD commands could utilize this tool to provide basic CAC training to their members.

In this thesis, we review basic properties of linear codes and lattices with a certain focus on their interplay. In particular, we focus on the analogous con- structions of cyclic codes and cyclic lattices. We start out with a brief overview of the basic theory and properties of linear codes. We then demonstrate the construction of cyclic codes and emphasize their importance in error-correcting coding theory. Next we survey properties of lattices, focusing on algorithmic lattice problems, exhibit the construction of cyclic lattices and discuss their applications in cryptography. We emphasize the similarity and common prop- erties of the two cyclic constructions.

The theses firstly introduces the basics of lattice problems. Then it focuses on various aspects of the cryptosystem NTRU which is based on the mentioned problems. The system is then compared with the most common encryption methods used nowadays. Its supposed quantum resistence is mentioned briefly. Subsequently the author tries to minimize the system's disadvantages by various cryptosystem modifications. Powered by TCPDF (www.tcpdf.org)