• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.5C
• /
• pp.523-531
• /
• 2003

Java applets are downloaded from web server through internet and executed in Java Virtual Machine of clients'browser. Before execution of java applets, JVM checks bytecode program with bytecode verifier and performs runtime tests with interpreter. However, these tests will not protect against undesirable runtime behavior of java applets, such as denial of service attack, email forging attack, URL spoofing attack, or annoying sound attack. In order to protect malicious applets, a technique used in this paper is java bytecode modification. This technique is used to restrict applet behavior or insert code appropriate to profiling or other monitoring efforts. Java byte modification is divided into two general forms, class-level modification involving subclassing non-final classes and method-level modification used when control over objects from final classes or interface. This paper showed that malicious applets are controlled by java bytecode modification using proxy server. This implementation does not require any changes in the web sever, JVM or web browser.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.7 no.2
• /
• pp.29-37
• /
• 2011

Java bytecode verification is a critical process to guarantee the safety of transmitted Java applet on the web or contemporary embedded devices. We propose a design of framework which enables to analyze and verify java bytecode. The designed framework translates from a java bytecode into the intermediate representation which can specify a properties of program without using an operand stack. Using the framework is able to produce automatically error specifications that could be occurred in a program and express specifications annotated in intermediate representation by a user. Furthermore we design a verification condition generator which converts from an intermediate representation to a verification condition, a verification engine which verifies verification conditions from verification condition generator, and a result reporter which displays results of verification.

• Journal of KIISE:Software and Applications
• /
• v.30 no.1_2
• /
• pp.73-80
• /
• 2003

The Java programming language is designed for developing effective applications in a heterogeneous network environment. Major problem in Java is its performance. many attractive features of Java make the development of software easy, but also make it expensive to support ; applications written in Java are often much slower than their counterparts written in C or C++. To use Java`s attractive features without the performance penalty, sophisticated optimizations and runtime systems are required. Optimising Java bytecode has several advantages. First, the bytecode is independent of any compiler that is used to generate it. Second, the bytecode optimization can be performed as a pre=pass to Just-In-Time(JIT) compilation. Many attractive features of Java make the development of software easy, but also make it expensive to support. The goal of this work is to develop automatic construction of code optimizer for Java bytecode. We`ve designed and implemented a Bytecode Optimizer that performs the peephole optimization, bytecode-specific optimization, and method-inlining techniques. Using the Classfile optimizer, we see up to 9% improvement in speed and about 20% size reduction in Java class files, when compared to average code using the interpreter alone.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.1
• /
• pp.90-99
• /
• 2003

Java applets are downloaded from web server through internet and executed in Java Virtual Machine of clients' browser. Before execution of java applets, JVM checks bytecode program with bytecode verifier and performs runtime tests with interpreter. However, these tests will not protect against undesirable runtime behavior of java applets, such as denial of service attack, email forging attack, URL spoofing attack, and annoying sound attack. In order to protect malicious applets, a technique used in this paper is java bytecode modification. This technique is used to restrict applet behavior or insert code appropriate to profiling or other monitoring efforts. Java byte modification is divided into two general forms, class-level modification involving subclassing non-final classes and method-level modification used when control over objects from final classes or interface. This paper showed that malicious applets are controlled by java bytecode modification using proxy server. This implementation does not require any changes in the web sever, JVM or web browser.

• Journal of Korea Multimedia Society
• /
• v.8 no.12
• /
• pp.1658-1668
• /
• 2005

This paper presents the bytecode-to-SIL translator which enables the execution of the java program in EVM(Embedded Virtual Machine) environment without JVM(java Virtual Machine), translating bytecodes produced by compiling java programs into SIL(Standard Intermediate Language) codes. EVM, what we are now developing, is a virtual machine solution that can download and execute dynamic application programs written in sequential languages like C language as well as object oriented languages such as C#, Java, etc. EVM is a virtual machine mounted on embedded systems such as mobile device, set-top box, or digital TV, and converts the application program into SIL, an assembly language symbolic form, and execute it. SIL is a virtual machine code for embedded systems, based on the analysis of existing virtual machine codes such as bytecode, MSIL, etc. SIL has such features as to accommodate various programming languages, and in particularly has an operation code set to accept both object-oriented languages and sequential languages. After compiling, a program written in java language is converted to bytecode, and also executed by JVM platform but not in other platform such as .NET, EVM platform. For this reason, we designed and implemented the bytecode-to-SIL translator system for programs written in java language to be executed in the EVM platform without JVM. This work improves the execution speed of programs, enhances the productivity, and provides an environment for programmers to execute application programs at various platforms.

• Journal of Korea Multimedia Society
• /
• v.7 no.6
• /
• pp.824-831
• /
• 2004

This paper presents the java bytecode-to-.NET MSIL intermediate language translator which enables the execution of the java program in .NET environments without JVM(java Virtual Machine), translating bytecodes produced by compiling java programs into MSIL codes. Java, one of the most widely used programming languages recently, is the language invented by James Gosling at Sun Microsystems, which is the next generation language independent of operating systems and hardware platforms. Java source code is compiled into bytecode as intermediate code independent of each platform by compiler, and also executed by JVM. .NET language such as C# and .NET platform in Microsoft Corp. has been developed to meet the needs of programmers, and cope with Java and JVM platform of Sun Microsystems. After compiling, a program written in .NET language is converted to MSIL code, and also executed by .NET platform but not in JVM platform. For this reason, we designed and implemented the java bytecode-to-.NET MSIL translator system for programs written in java language to be executed in the. NET platform without JVM. This work improves the execution speed of programs, enhances the productivity, and provides a environment for programmers to develop application programs without limitations of programming languages.

• Journal of KIISE:Computing Practices and Letters
• /
• v.6 no.3
• /
• pp.356-363
• /
• 2000

Java programming language is designed to run effectively on internet and distributed network environments. However, because it has a deficit to be executed by the interpreter method on each platform, to execute Java programs efficiently the code generation system which transforms Bytecode into SPARC code as target machine code must be developed. In this paper, we implement a code generation system which translates Bytecode into SPARC code using the retargetable code generating techniques. For the sake of code expander, we wrote a Bytecode table describing a rule of SPARC code generation from Bytecode, and implemented the information extractor transforming Bytecode to suitable form during expanding of source code from class file. The information extractor determines constant pool entry of each Bytecode instruction operand and then the code expander translates the Bytecode into SPARC code accoring to the Bytecode table. Also, the retargetable code generation system can be systematically reconfigured to generate code for a variety of distinct target computers.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.37 no.4
• /
• pp.1-8
• /
• 2000

The massive growth of the internet and the world-wide-web leads us to research the programming languages for the development of applications in heterogeneous, network-wide distributed environments. Java is an object-oriented language for such a environment and the Java programming language environment provides a portable, interpreted, high-performance, simple programming language. Bytecode is an intermediate code for Java language and it enables the development of applications on multiple platform in heterogeneous, distributed networks. But it takes much time to execute Bytecode because of using an interpretation method. In this paper, we design and implement a retargetable code generation system which can be systematically reconfigured to generate code for a variety of distinct target computers. From the system, we realize the code generation system which translates the Bytecode being produced by Java compiler into Pentium target code. We use ACK code generation system to do the work easily.

• The Journal of the Korea Contents Association
• /
• v.6 no.1
• /
• pp.160-169
• /
• 2006

This paper describes the data structure for program analysis and optimization of bytecode level. First we create an extended CFG(Control Flow Graph). Because of the special properties of bytecode, we must adaptively extend the existing control flow analysis techniques. We build basic blocks to create the CFG and create various data that can be used for optimization. The created CFG can be tested for comprehension and maintenance of Java bytecode, and can also be used for other analyses such as data flow analysis. This paper implements CTOC's CTOC-BR(CTOC-Bytecode tRanslator) for control flow analysis of bytecode level. CTOC(Classes To Optimized Classes) is a Java bytecode framework for optimization and analysis. This paper covers the first part of the CTOC framework. CTOC-BR is a tool that converts the bytecode into tree form for easy optimization and analysis of bytecode in CTOC.

• Journal of Korea Multimedia Society
• /
• v.7 no.7
• /
• pp.976-984
• /
• 2004

C# and .NET platform in Microsoft Corp. has been developed to meet the needs of programmers, and cope with Java and JVM platform of Sun Microsystems. After compiling, a program written in .NET language is converted to MSIL code, and also executed by .NET platform but not in JVM platform. Java, one of the most widely used programming languages recently, is the language invented by James Gosling at Sun Microsystems, which is the next generation language independent of operating systems and hardware platforms. Java source code is compiled into bytecode as intermediate code independent of each platform by compiler, and also executed by JVM. This paper presents the MSIL-to-Bytecode intermediate language translator which enables the execution of the program written in .NET language such as C or C# in JVM(Java Virtual Machine) environment, translating MSIL code produced by compiling .NET program into java bytecode. This work provides an environment for programmers to develop application programs without limitations of programming languages.