The reverse execution of programs is a function where pro-grams are executed backward in time. A reversible debugger is a debugger that provides such a functionality. In this pa-per, we propose a novel reversible debugger that enables reverse execution of programs written in the C language. Our approach takes the virtual machine based approach. In this approach, the target program is executed on a special virtual machine. Our contribution in this paper is two-fold. First, we propose an approach that can address problems of (1) compatibility and (2) efficiency that exist in previous works. By compatibility, we mean that previous debuggers are not generic, i.e., they support only a special language or special intermediate code. Second, our approach provides two execution modes: the native mode, where the debuggee is directly executed on a real CPU, and the virtual ma-chine mode, where the debuggee is executed on a virtual machine. Currently, our debugger provides four types of trade-off settings (designated by unit and optimization) to consider trade-offs between granularity, accuracy, overhead and memory requirement. The user can choose the appro-priate setting flexibly during debugging without finishing and restarting the debuggee.

Regression testing is testing applied to software that has been modified. It basically entails re-testing the software with previous test cases to confirm that the modifications made to the software do not have an adverse effect. But re-executing all test cases is normally cost prohibitive, and thus much research has been done on selecting test cases from a test suite without compromising the reliability of the software. These regression test selection techniques find test cases that will not detect any bugs in the modified software, and delete those from the next regression test suite. However, these techniques are based on analysis of source code. Recent programming environments have seen a proliferation of virtual machines. For example, programs written in Java and with the Microsoft .Net Framework are compiled into a platform-independent intermediate code which is executed. Such code could also be used for regression test selection. This especially holds for the Microsoft .Net Framework which handles various programming languages, such as Visual Basic and C++. Thus, this paper presents a safe regression test selection technique for virtual machine based programs. We especially target the Microsoft .Net Framework. Evaluation on 10 different examples resulted in an average of a 40.4% decrease in the cost of regression testing.

This paper evaluates the effects of IP packet loss and picture frame reduction on MPEG1 subjective quality in order to clarify how to apply quality-guaranteed techniques such as RSVP (resource reservation protocol) to the Internet. Subjective assessment tests showed that IP packet loss was the dominant factor in MPEG1 audio-visual quality degradation compared with picture frame reduction. Moreover, there was no difference between individual audio-visual quality contributions to the overall MPEG1 quality.

The augmented encrypted key exchange (A-EKE) uses a shared secret key for encryption. The A-EKE uses the hash of sender's password as the shared secret key. By using Simmon's attack the sender's password can be broken. If this is accomplished, the attacker is able to know the communicating parties session key used after authentication as well as in the authentication of the sender. Furthermore, using the broken session key and the password, the attacker can impersonate the real sender. To prevent this from happening, we propose a method to keep the session key and sender's password secret even if the attacker can break the shared secret key. This is accomplished by using RSA encryption. In our proposed scheme we use public keys which will be kept by the communicating parties and will be exchanged indirectly, i.e. instead of sending the whole public key the two parties will send the number which determines their public key, along with the shared key.

Smalltalk-80 (hereafter referred to as Smalltalk), which is one of the most productive programming languages/environments, is very well suited for prototyping of applications but it is less well suited for delivering applications because applications can neither run in isolation from the Smalltalk environment nor be combined with other programs written in other languages. One way to make Smalltalk suitable for delivering applications is to translate Smalltalk into a compiler language such as C. By translating Smalltalk code into portable and interoperable C code, it is possible to deliver a stand-alone version of Smalltalk applications, and to develop an application partly in Smalltalk and partly in C. However, there are some difficulties in translating Smalltalk code into such a C code. First, the execution model of Smalltalk, which creates activation records as objects, is very different from that of C, and second, Smalltalk and C have very different approaches to storage management. We have implemented SPiCE, a system for translating Smalltalk into C. Our approach to the translation is to create runtime replacement classes implementing the same functionality of Smalltalk classes that are inherently part of the Smalltalk execution model, and to provide semi-conservative real-time compacting garbage collection that works without language support.>

HoME is a version of Smalltalk which can be efficiently executed on a multiprocessor and can be executed in parallel by combining a Smalltalk process with a Mach thread and executing the process on the thread. HoME is nearly the same as ordinary Smalltalk except that multiple processes may execute in parallel. Thus, almost all applications running on ordinary Smalltalk can be executed on HoME without changes in their code.