Amongst our main research interests is the security of payment systems and fair exchange, and anonymity protocols. The importance of various digital cash systems, e.g. Bitcoin, and the concept of blockchains, should not be underestimated. For this reason, we have been conducting research in the fields of Bitcoins and fair exchange protocols. For example, we have examined how Bitcoins can be used to offer optimistic fair exchange and anonymity. We have also worked in the field of centralised payment systems. This research thread is currently leading us into further research questions related to NFC payments, where we have practically examined the efficient use of mobile phone sensors for avoiding relay attacks. We have also identified a PIN related weakness in the existing EMV payment protocols, and we have proposed countermeasures. We have also been working on enhancing EMV contactless mobile payments using tokenisation, Over-The-Air (OTA) and mobile phone ambient sensors. More recently we have also examined the security of mobile payments in relation to tokenisation and secure elements. We have also proposed payment systems suitable for use in offline environments.