Technological innovation has enabled tiny devices to participate in pervasive com- puting. Such devices are particularly vulnerable to security and privacy threats, because of their limited computing resources and relatively weak physical security. We investigate possible cryptographic solutions to security and privacy problems arising in two kinds of emerging pervasive computing networks: Personal Area Net- works (PANs) and the EPCglobal Network. A number of key management schemes have been proposed for use in PANs, but these schemes only support key management within a PAN. However, as people are increasingly equipped with multiple wireless devices, PANs are likely to be intercon- nected to share information or services. We introduce a term, iPANs, to name such interconnected PANs. We define system models and design goals for key manage- ment in iPANs, and propose a novel security initialisation scheme for use in iPANs. The proposed scheme achieves desirable security and efficiency properties by making use of the unique characteristics of PANs. The EPCglobal Network is designed to give efficiency and cost savings in and beyond the supply chain using Radio Frequency Identification (RFID) technology; however, privacy threats affecting such networks are particularly serious. We construct a formal privacy model for RFID systems accurately reflecting adversarial threats and power. We then give brief privacy analysis for the existing privacy-enhanced RFID schemes which have received wide attention in the literature. We then construct a secure refresh-based RFID system based on re-encryption techniques, and prove its privacy using the defined privacy model. Finally, we show that the proposed scheme can greatly enhance the security and privacy of EPC tags, making the maximum use of given tag functionalities as specified in the standards.

As computers reach more aspects of our everyday life, so too do the passwords that keep them secure. Coping with these passwords can be a problem for many individuals and organisations who have to deal with the consequences of passwords being forgotten, yet little is known of this issue. This thesis considers the effectiveness of password authentication systems for three groups of stakeholders including users, support staff, and system owners. The initial problem of how to create memorable but secure passwords is reconceptualised as how to improve password system effectiveness. Interview, questionnaire, and system log studies in BT, and experiments at UCL-CS confirm some basic hypotheses about key variables impacting performance, and show that other variables than the memorability of password content are also important which have hitherto not figured in security research and practice. Interventions based on these findings are proposed. Empirical evaluation suggests that the interventions proposed that 'redesign' the user but exclude other parts of the system would fail. Reason's (1990) Generic Error Modelling System (GEMS) is used as a basis for modelling password system performance at the level of individual users. GEMS and the Basic Elements of Production are used generalise these findings, and for the first time to model information security. This new model, "Elevation", is validated by expert review, and a modified version is presented.

This research is in the field of document security and the investigation of existing security devices. Security documents can be of two types; those that have commercial value, namely currency, articles of value and those that have legal value, namely, passports, identification cards etc. It is of vital importance in today's world, where fraud and counterfeiting are the order of the day, to protect any article or document of aesthetic importance and value. After the tragic events of September 11th 2001, security and the lack of security in every sense of the word is a much talked and researched subject. The literature review in Chapter Two will reveal that there are many security devices being currently used for various applications and each of them has many advantages and disadvantages. Devices such as magnetic cards, chip cards, biometric technology, optically variable devices, holograms and kinegrams and others have been described and their uses explained. Chapter Three is a continuation of literature review on Digital Watermarking and the available Digimarc technologies and applications in the field of security. Digimarc Corporation, based in Tualatin, Oregon, United States has been the pioneer in the field of Digital Watermarking. Microbar Security Limited, a subsidiary company of Durand Technology Limited, based at the Shrivenam 100 Business Park, Shrivenam, Oxfordshire, United Kingdom has developed its own watermarking technique, which has many advantages in comparison to the Digimarc Technology has also been described here.In Chapter Four, an optical variable device, namely, the Lippmann Optical Variable Device, named after the nineteenth century scientist Gabriel Lippmann (1845-1921), has been studied in thorough detail. Much work has been done to prove it and to understand the principle behind the theory he proposed. Currently, this type of technique based on interferential photography can be applied as a unique security device on passports, identification cards etc. The principles and theory of Lippmann photography has been explained in considerable detail. Experimental work done using various methods and using different photographic materials has also been described along with the results obtained. The application that has been emphasized here, is for passports for which this research was conducted in collaboration with Holographic Dimensions, Florida. Chapter Five, explains the principle of Covert Bar Coding which is the basis of the Microbar Watermarking Technique. Experimental results have been presented, these have been obtained using the MATLAB software. Finally, Chapter Six gives some ideas that can be pursued for future work. This work has produced two papers on Lippmann Photography and the mathematical evaluation of the emulsion co-authored by the author of the thesis. Abstracts from the papers have been used in this thesis. Also, it has produced two patents, one by `Holographic Dimensions', Florida on the Lippmann Photography and second, `Microbar Security Limited' on the `Covert Bar Coding Technique'.

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