Due to convenience and efficiency, electronic voting (e-voting) techniques gradually replace traditional paper-based voting activities in some developed countries. A secure anonymous e-voting system has to satisfy many properties, such as completeness, tally correctness, and uncoercibility, where the uncoercibility property is the most difficult one to be achieved. Since each voter can obtain a voting receipt in an electronic voting system, coercion and bribe (vote-buying and vote-selling are included) become more and more serious in electronic voting environments than traditional paper-based voting environments. Unfortunately, most of the solutions, like receipt-freeness or untappable channels, proposed in the literature, are impractical owing to lack of efficiency or too complicated to be implemented. It will make uncoercible e-voting systems unacceptable by the people. In order to cope with the drawbacks of the previous schemes, this thesis will present a generic idea, which is independent of the underlying cryptographic components, on electronic voting to achieve the uncoercibility property and other requirements. The proposed method is an efficient and quite practical solution to match the current environments of electronic voting.

Mobile network equipments are widely popularized and advanced mobile communication services are provided increasingly such that ubiquitous computing environments will come true soon. It is a pleasure for mobile users to work or get recreations in the mobile network environments. However, just as the cases in wireline environments, there are a lot of security threats to mobile network systems and their impact on the security is more serious than that in wireline environments owing to the feature of wireless transmissions and the ubiquity property in mobile network systems. The secret personal information, important data, or classified missives which mobile users carry may be stolen by malicious entities. In order to guarantee the quality of the advanced communication services, the security and privacy would be the important issues when mobile users roam to the mobile networks. In this thesis, an anonymous authentication protocol will be proposed to protect both the security of the mobile network system and the privacy of mobile users. Not only does the proposed scheme provide mutual authentication between each user and the system, but also the identity of each user can be kept secret against anyone else including the system. Although the users are anonymously authenticated by the system, it can still make correct bills to charge these anonymous users. Finally, our protocol also achieves the goal of fair privacy which allows the judge to be able to revoke the anonymity and trace the illegal users when they misused the anonymity property such as they committed crimes.

In this thesis, an FPGA based hash processor is designed and implemented using a hardware description language / VHDL. Hash functions are among the most important cryptographic primitives and used in the several fields of communication integrity and signature authentication. These functions are used to obtain a fixed-size fingerprint or hash value of an arbitrary long message. The hash functions SHA-1 and SHA2-256 are examined in order to find the common instructions to implement them using same hardware blocks on the FPGA. As a result of this study, a hash processor supporting SHA-1 and SHA2-256 hashing and having a standard UART serial interface is proposed. The proposed hash processor has 14 instructions. Among these instructions, 6 of them are special instructions developed for SHA-1 and SHA-256 hash functions. The address length of the instructions is six bits. The data length is 32 bits. The proposed instruction set can be extended for other hash algorithms and they can be implemented over the same architecture. The hardware is described in VHDL and verified on Xilinx FPGAs. The advantages and open issues of implementing hash functions using a processor structure are also discussed.

Past few decades witnessed the birth and explosive growth of the internet and the communications &ndash / most notably the electronic mail- through it. Studies indicate that although security measures are deployed, their usage is very limited and problematic. This work proposes a system to address some of the shortcomings of present mail security systems, such as underutilization, complicated key management and unwanted immunization against filtering-scanning. A two-layer message encryption scheme with domain level keys is introduced and a performance analysis is presented. An analysis of the improvement on the key management is also presented. Results show that, e-mails can be secured without significant performance impact, and visible ease of key management, by using the system proposed in this thesis.

With fast and prosperous development in communication technology, desktop or mobile devices may be equipped with wired and wireless network interfaces. Hence, users need a multihoming technique to help them making use of the network in- terfaces effectively. The Stream Control Transmission Protocol (SCTP) is a new transport protocol approved by the SIGTRAN Working Group of IETF (Internet Engineering Task Force) as RFC 2960 in October 2000 where it includes this useful characteristic. However, this feature may lead to some secure pitfalls. In this thesis, we come up with some approaches to improve SCTP against some existing tough problems raised from multihoming and provide more sufficient protection methods based on cryptography. Finally, a comparison of the existing security solutions is also given to demonstrate our contributions.

<p>Many of the products commercially available today contain some form of encrypted or hashed data. It can involve DRM protection, licenses and certificates, signatures or identification information. Regardless of what the data is intended for, it is protected for a reason and may be worth a great deal of money to the owner.</p><p>There are numerous examples of products that have been subject to hacking in the form of simple memory attacks. If the keys are made all too easily extracted, the value of the protected data will soon be lost.</p><p>The aim of the thesis work discussed in this report was to evaluate the vulnerabilities in mobile phones to this sort of attacks and to find possible security enhancements that can be applied. A method is proposed where masking will secure the cryptology keys while they reside in the memory.</p><p>Different masks are developed and tested - The effects on performance are measured and the security is evaluated.</p><p>The thesis work concludes that it is possible to implement masking on many of the security functions using keys and that the masks will increase security. The conclusion also states that the time consumption of the masking heavily depends on which mask that is used and that the masking could be applied in such a way that the level of masking can be varied.</p>

<p>Stream ciphers are counted as an important part of symmetric encryption method. Their basic idea comes from One-Time-Pad cipher using XOR operator on the plain text and the key to generate the cipher. The present work brings a new idea in symmetric encryption method, which inherits stream key generation idea from synchronous stream cipher and uses division instead of xoring. The Usage of division to combine the plain text with stream key gives numerous abilities to this method that the most important one is using random factors to produce the ciphers.</p>

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: NTRU; cryptography; scalable multiplier; unified multiplier; Montgomery multiplier. Includes bibliographical references (p. 85-88).

Thesis (M.S.)--Literature, Communication, and Culture, Georgia Institute of Technology, 2004. / Eugene Thacker, Committee Chair ; Xin Wei Sha, Committee Member ; Stephen Mamber, Committee Member ; Jay Bolter, Committee Member. Includes bibliographical references (leaves 87-89).

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, June 2004. / Thesis advisor(s): J.D. Fulp, Dan C. Boger. Includes bibliographical references (p. 159-160). Also available online.