The Research And Implementation Of Java Card Bytecode Optimization

As a new kind of smart card based on Java language, Java card is widely used in the highly security fields such as bank, social security etc. An applet executing on a Java card, faces scarce memory resources and fixed execution time constraints. For this reason, it is extrodinary essential to optimize the cap files which are loaded to the Java card. This paper attempts to design and implement a Java card bytecode optimizator synthetical used redefining instructions and Basic-Block Compression based on the analysis characteristics and disadvantages of the existing methods.The research key point of this paper is the structure of the bytecode file and the optimized method. Firstly, we consult the existing Java byte code optimization from the analysis of the Java card virtual machine and Java card byte code files construction, and put forward a hybrid model compression algorithm optimization based on hybrid model. Then through the optimization we can obtain the bytecode files which have smaller size with a minimal execution time penalty. Then we analyze the process of the applications running on the Java card and the hardware resources on card; design a feasible and effective on-card decompression algorithm. At last, the details scheme of Java card Optimizator based on off-card compression and on-card decompression including constructing environment for development, rewriting the Java card virtual machine and implementing the Optimizator. The result and discussion of simulation and some suggestions of improving the efficiency of optimizator efficiency are given in the last part of this paper.