Instruction Folding Compression for Java Card Runtime Environment

Java Card is a secure Java running environment targeted for smart cards. In such low-end embedded systems, ROM size and execution time play very important, usually opposing roles. Dictionary compression can be applied to the Java Card software architecture, but pays for the reduced ROM size of the applications with a higher execution time. On the other hand, acceleration mechanisms to speed up the execution need additional information or additional software complexity, with the effect of increasing ROM size. In this paper, we propose a dictionary compression system based on an instruction folding mechanism that permits a reduction in the ROM size of Java Card applications, and at the same time, a speed-up of their execution.