Deducing Similarities in Java Sources from Bytecodes

Several techniques for detecting similarities of Java programs from bytecode files, without access to the source, are introduced in this paper. These techniques can be used to compare two files, to find similarities among thousands of files, or to compare one new file to an index of many old ones. Experimental results indicate that these techniques can be very effective. Even changes of 30% to the source file will usually result in bytecode that can be associated with the original. Several applications are discussed.