My primary research interests all concern issues relating to information security, an area of increasing importance with the infiltration of computer networks into almost all aspects of life and work. Within information security, although I am originally a specialist in cryptography, my research interests are gradually broadening over time!

High level current and recent research interests are specified below. These are intended to be generally accessible. Those seeking more details are recommended to see my list of publications.

Information for Masters students seeking project supervision.

This is the study of using discrete mathematical structures to model information security problems and prove results concerning their efficiency. This is of particular interest to the research community as combinatorial models are useful for designing unconditionally secure cryptographic schemes, whose security is independent of the resources available to an attacker.

Secret sharing schemes provide a means of sharing information amongst a number of entities in such a way that only certain specified entities can recover the information. Much of my research has been based on exploring various aspects of secret sharing, exploiting geometrical properties to design efficient and practical schemes, as well as to add a number of useful features to the basic concept such as the ability to initiate such systems without the involvement a trusted party to enable the scheme, the ability to re-use a scheme many different times,  the ability to efficiently merge different schemes into one, and the problem of introducing aspects of anonymity into the secret reconstruction process. I continue to maintain an interest in this area.

• EPSRC project: Dynamic update of shared control systems
• Geometrical contributions to secret sharing theory is a review of the projective geometry approach to linear secret sharing schemes.
• For an overview of certain aspects of secret sharing research please see slides and paper from invited presentation at the Cryptography and Coding Workshop hosted by the Royal Flemish Academy for Science and the Arts in September 2007.
  

I have also looked at other combinatorial cryptographic problems, such as the investigation of authentication and secrecy schemes, as well as more complex key distribution problems that allow multiple groups of entities to establish common cryptographic keys (see key management). In all these investigations the ability to apply discrete mathematical tools in different environments has proved useful to construct viable schemes, and the use of information theoretic models has been useful to prove results about their optimality. 

In distributed cryptography the computation of basic cryptographic primitives can be shared out amongst a number of network entities, bringing advantages with respect to availability and weakened trust requirements. I have looked at several problems in distributed cryptography, including:

• the ability to distribute the generation of an authentication tag in unconditionally secure authentication schemes.
• techniques for distributing the computation of a block cipher across a number of network entities. 
• the metering of access to web sites, where several different servers monitor client visits and record evidence that can later be used to claim advertising revenue.
• distributing the capabilities of a Certificate Authority in an ad hoc networking environment.

The general problems associated with management of cryptographic keys are another of my ongoing research interests. Research interests in this area include:

• Combinatorial modelling of key establishment schemes. For an overview see an invited presentation at the 2007 British Combinatorial Conference:
• paper
• slides
  
• Theoretical and practical aspects of proposals for schemes that permit the recovery of cryptographic keys.  
• Key management architectures for mobile environments.
• Key establishment and management techniques for highly distributed environments such as wireless sensor networks, where nodes in the network are severely limited in their abilities to store information and perform computations.
• Cryptographic access control.
  

I am also interested in other aspects of cryptographic research. These include:

• Cryptographic protocols, particularly for mobile authentication and payment for mobile services.   
• The relationship between digital watermarking, which is the study of techniques for embedding information into data (primarily to establish various different kinds of digital rights) and cryptography.
• Cryptographic primitive design and application, particularly hash functions.

• Security issues in MANETs, particularly wireless sensor networks.
• Privacy, and its associated technologies.