The Analysis And Research Of Mixed Encryption Algorithm For Java Class File

Java is an important symbol of computer technology development and information exchange. It has the advantages of simple operation, strong compatibility and so on. It changes the development mode of traditional software and brings new changes of software. Therefore, it is widely used in software development. The increasingly usage of Java has brought a huge test in the security protection of software. Although Java can be cross-platform with pleasant flexibility and has a separated way of compiling, the source code does not generate Binary file but a kind of file named Java class file against the virtual machine. Java class file belongs to the interlayer code with certain format which easily decompiled by hacker.The similarity between the decompiled code and the source code result in the phenomenon of file stealing.In order to avoid such phenomenon,it is imperative to improve the measure of protection of Java class files.In recent years,aimed at the protection of the Java class files,enterprises and Java developers have put forward a series of protective measures like native compilation, code isolation technique,code obfuscation technique and digital watermarking technique after deeply analyzing the underlying class loading mechanism.Based on the further study of the protection situation and technology of Java class file and predecessors' research,this paper summarizes the main algorithm of the existing technology of Java class file protection and their advantages and disadvantages.The traditional encoding techniques like RSA,AES,which have limited length of encryption,exist abnormal phenomenon when we encrypt some complicated and long data.Therefore,this paper presents a block RSA encryption algorithm for Java class file, which can effectively encrypt and decrypt long data,save encryption and decryption time,improve the efficiency of the algorithm,and has an important research significance.In a relatively safe network environment,the programmers tend to ignore the protection of their code.So this paper designed a set of low transparent class file protection mechanism with JNI,class loader and so on,and analyzed and tested the validity and reliability of the class file protection mechanism.Main works the paper finished:1 .We used JNI along with the language of C++ to encrypt Java class file.The tool class to encrypt other class file is always exposed,which asked us to design it into dynamic link library.2.We designed the algorithm of encryption and decryption and tested the code.The result of test directly verifies the algorithm's performance.By the way,we opt the manual test to finish various aspects exam s of designed algorithm.3.We decrypted class file by classloader.In order to hiding the detail of decryption,this paper employed designed classloader which embedded with decryption algorithm to decrypt Java class file.Since the classloader is also a kind of class file,we must encrypt it and eventually realize the decryption and calling of the classloader by changing the jvm.