Degree Name

Master of Computer Science (Research)


School of Information Technology and Computer Science - Faculty of Informatics


Personal Digital Assistants (PDAs) are one of the most popular computing tools nowadays. Compared with desktop and notebook computers, PDAs are smaller, lighter and can be carried everywhere. However, PDAs have several limitations. They use smaller microprocessors which are much slower than their PC counterparts. Their lack of computational power makes it very difficult to perform some heavy computations, such as generating RSA keys, which needs large prime numbers. Thus, it is useful to have a combination of a PC and a PDA, where the PC performs heavy computations to assist the PDA. This scenario is feasible as long as we assure that the PC will not learn the secret of the PDA. We propose two schemes, which involve some server-aided computations, where the server will not learn the PDAs secret from the interaction. This thesis also investigates the security of PDAs when they are used to perform some cryptographic applications. Due to the limited computational power of PDAs, such computations require some amount of time (and battery life). We show that by observing one of the parameters, we can reduce the hard problem being predictable. We also propose how to securely generate these kinds of computations in PDAs by using some different techniques, so that it will not reveal any additional information to a passive eavesdropper. In addition, along with their popularity, handheld devices are starting to become the target for attackers, who are mainly interested in gaining the data stored in handheld devices. In this thesis, we review the security threats to handheld computers and propose two possible solutions. The first solution is to use a desktop computer to act as a bastion host to protect the handheld computer. The second proposed solution is to build a personal firewall for handheld computers.


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