Hot updates for Java based smart cards

Systems need to be updated in order to correct vulnerabilities, fix bugs but also to enhance functionalities. Traditional software update mechanisms usually stop the software that need to be updated, apply the update then restart the system. However, this approach is not appropriate in critical systems such as banking or telecommunications. A solution is the dynamic software update (DSU) approach which patches the software on-the-fly (i.e. during execution). Several mechanisms have been proposed to offer this functionality to native and virtual machine environments for desktop and server computers. But using DSU in embedded systems (and especially in smart cards) raises several challenges regarding the resource and security constraints. In this paper, we present our work, EmbedDSU, a framework for DSU on Java based smart cards. The first part of EmbedDSU is an off-card mechanism which computes the changes between two versions of classes. This limits the update process only on the part of the component which is affected by the modification. The second part of EmbedDSU is the interpretation of the changes on-card and update of the methods in the class definition and object instances.