US 7493596 B2
An analysis tool extracts class data from Java objects within a potential plagiarizing Java program and the original Java program, and then compares classes common to the potential plagiarizing program and the original across various performance metrics. Similarities disclosed by the analysis tool are output for user or programmatic comparison of the matches between the potentially plagiarizing Java program byte code and the original program's byte code.
1. A method for evaluating Java software to determine similarity with other Java software, the method comprising the steps of:
extracting class data from compiled code of a software program;
extracting class data from an compiled code of an original software program;
determining class data of the software program matching the class data from the original software program;
outputting the comparison as a function of class data; and
determining a similarity of the software program to the original software program based on the comparison output;
wherein the determining occurs even if a Java source code is not available for at least the software program.
2. The method according to
the class data includes method signatures, byte codes and byte arguments; and
the method further comprises storing the class data in a database.
3. The method according to
4. The method according to
the software programs are determined to be similar according to statistical analysis based on the comparison output; and
the method further comprises:
compiling the information for each software program into a matrix to facilitate the comparison
executing a text mining algorithm on the matrix for each common method of both the software program and original software program to determine similarities between the two methods, wherein the text mining algorithm determines similarities based on one or more of clustering, classification, and association) performs.
5. The method according to
6. The method according to
The present application is related to the following co-pending U.S. patent applications filed on even date herewith, and incorporated herein by reference in their entirety:
Ser. No. 10/881,967, entitled “METHOD, SYSTEM AND PROGRAM PRODUCT FOR DETERMINING STANDARD JAVA OBJECTS”
Ser. No. 10/881,969, entitled “METHOD, SYSTEM AND PROGRAM PRODUCT FOR EVALUATING JAVA SOFTWARE BEST PRACTICES ACROSS MULTIPLE VENDORS”
Ser. No. 10/881,968, entitled “METHOD, SYSTEM AND PROGRAM PRODUCT FOR OPTIMIZING JAVA APPLICATION PERFORMANCE THROUGH DATA MINING”
1. Field of the Invention
The present invention relates to computer systems, software architectures and programs, and more particularly to a method, system and computer program product for evaluating Java programs to determine code plagiarism.
2. Description of the Related Art
Java is a robust, portable object-oriented programming language developed by Sun Microsystems, Inc., that is gaining wide acceptance for writing code for the Internet and World Wide Web (hereinafter, “Web”). The nature of Java programming allows programmers to easily decompile Java code and review its source code. As such, competitors are able to obtain software from other vendors and review their source code as part of their process of developing their own Java programs. It is a simple matter for the Java source code itself to be copied into the new software program being developed. This copying of the Java source code infringes on the copyright of the original author of the Java source code. Unfortunately, there are few tools available to discover such code plagiarism, and the typical detection devices that are available are easily fooled when the plagiarizing source code is slightly modified or changed from the original source code.
This difficulty in detecting code plagiarism is further complicated when source code for the infringing software is not available. There are a variety of this obfuscation programs that limit access to source code of a program. Without viewing the original source code, it is extremely difficult to determine if program code has been copied. Using artificial intelligence algorithms, software can analyze source code for keywords, patterns, and compare them to known software programs. If duplication of a known software program is found within a certain probability, the new code is considered to be copied or duplicated. However, such a technique has hereto only been capable of detecting such patterns in source code.
Accordingly, it would be valuable to provide a tool for detecting code plagiarism and intellectual property infringement of a java program, even when the original code has been modified somewhat by the plagiarist. Such a tool would have particular value if you could detect code plagiarism even if the Java source code was not available.
In accordance with one embodiment of the present invention, an analysis tool extracts class data from a potentially infringing software program and an original program, and then determines what class data of the software program matches the class data from the original software program. The analysis tool then outputs the comparison as a function of class data. The tool or user can then determine the similarity of the software program to the original software program based on the comparison output.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.
This invention is described in a preferred embodiment in the following description with reference to the drawings, in which like numbers represent the same or similar elements, as follows:
In a preferred embodiment, the present invention provides a facility to analyze Java byte code to determine if the code has been plagiarized from another source program. This is accomplished by an analysis tool performing a pre-analysis to train itself on particular programming metrics of the original program, and then performing a dynamic analysis of the potentially plagiarizing or infringing Java program to determine if its byte code matches the criteria or programming metrics extracted from the original program's byte code. The function of the analysis tool in a typical software environment is described below.
In the following detailed description of exemplary embodiments of the invention, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical and other changes may be made without departing from the spirit or scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. In particular, although the preferred embodiment is described below with respect to a Java software system, it will be appreciated that the present invention is not limited to Java implementations.
Display adapter 110 operatively couples a display device 116 to system bus 104. A disk storage device (e.g., a magnetic or optical disk storage device) 118 is operatively coupled to system bus 104 by I/O adapter 112. User interface adapter 114 operatively couples a mouse 120 and keyboard 124 to system bus 104. One or more objects are created when an Object-Oriented Program (not shown) is executed in computer system 100.
The present invention has particular utility in Java applications. Java is a robust, portable object-oriented programming language developed by Sun Microsystems, Inc. Java attains its portability through use of a virtual machine or “Java Virtual Machine”, or “JVM”. The JVM enables isolating the details of the underlying hardware from the compiler used to compile the Java programming instructions.
Java applications are typically constructed using a development toolkit such as the “JDK” (Java Development Kit) product from Sun Microsystems, and are executed using the “JRE” (Java Runtime Environment) product, also from Sun Microsystems. Programs are executed from the command line when using the JRE. The Java Runtime Environment includes the JVM, as well as a number of files and classes that are required to run Java applications or applets. Hereinafter, the terms “JVM” and “runtime environment” will be used interchangeably unless otherwise noted.
Java program source code typically consists of a set of class definitions stored in a series of text files. A Java class contains both methods and data. Java source code is compiled into binary code, referred to as Java “byte code.” Byte codes are machine independent so that they can be executed on any machine's JVM, where the JVM is tailored to the specific operating environment. After the source code files are compiled into Java byte code class files, they are then typically loaded into memory by a class loader for interpretation by a JVM interpreter before the associated program is executed. Class loading can also occur when a Java program dynamically attempts to load another class at run time. The Java class loader uses a predetermined search strategy when locating class files, which gives precedence to particular locations. According to the Java 1.2 platform specification, the highest priority search locations are the bootstrap run time and internationalization classes in the JRE, named “rt.jar” and “I18N.jar,” respectively. The Java Archive (JAR) or “.jar” file is a repository that contains one or more Java class files and is simply called a “Java jar” or “JAR”. JAR files provide compression, backward compatibility with existing Java applets, portability, and security features.
With reference now to
BCI 200 decompiles a known Java class or JAR file (known Java files 208) to extract specific method information to be placed in database 202.
BCI 200 retrieves methods of a class being analyzed from a commercially available toolkit called the byte code engineering library (BCEL) 206. In a preferred embodiment, BCI 200 has been implemented using a publicly available byte code engineering library such as the open source Byte Code Engineering Library, which is available from The Apache Software Foundation on the Internet at http://jakarta.apache.org/index.html. This library is used to separate a Java class file into its constituent parts.
With reference now to
With reference now to
At step 808, BCI 200 analyzes each of the methods found in step 806 for programming metrics of interest, for example, such as size of the code, security implemented, performance provided, etc. At step 810, each of the analyzed classes, dependencies and metadata are stored in a database.
With reference now to
Thereafter, the process proceeds to step 1010, where BCI 200 determines the similarity between the compared codes based on the detected similarities at step 1008. BCI 200 would demonstrate the similarities at step 1010 by generating a visual representation of the comparison using a visualizing tool. For example a WEKA machine learning GUI tool could be used.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, the present invention may be implemented using any combination of computer programming software, firmware or hardware. As a preparatory step to practicing the invention or constructing an apparatus according to the invention, the computer programming code (whether software or firmware) according to the invention will typically be stored in one or more machine readable storage mediums such as fixed (hard) drives, diskettes, optical disks, magnetic tape, semiconductor memories such as ROMs, PROMs, etc., thereby making an article of manufacture in accordance with the invention. The article of manufacture containing the computer programming code is used by either executing the code directly from the storage device, by copying the code from the storage device into another storage device such as a hard disk, RAM, etc., or by transmitting the code for remote execution. The method form of the invention may be practiced by combining one or more machine-readable storage devices containing the code according to the present invention with appropriate standard computer hardware to execute the code contained therein. An apparatus for practicing the invention could be one or more computers and storage systems containing or having network access to computer program(s) coded in accordance with the invention. While this invention is described in terms of the best mode for achieving this invention's objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the present invention.