Project TRANSPROSE is a comprehensive research project investigating techniques for transporting programs securely over potentially insecure channels. The central focus of this project is the development of a blueprint for a next-generation mobile-code distribution format. A problem of previous approaches to mobile-code security has been that the additional provisions for security lead to a loss of efficiency, often to the extent of making an otherwise virtuous security scheme unusable for all but trivial programs. TRANSPROSE strives to deviate from the common approach of studying security in isolation and instead focuses simultaneously on multiple aspects of mobile-code quality. Besides security, such aspects include encoding density, speed of dynamic code generation, and the eventual execution performance. This paper gives a high-level overview of project TRANSPROSE and presents initial results, which include a highly-effective syntaxbased compression scheme for Java programs, as well as a performance-oriented intermediate program representation providing guaranteed security.

Abstract syntax trees (ASTs) have numerous advantages as a mobile code format over the more commonly used bytecode-based formats. Not only are ASTs portable, inherently safer, and more suitable for optimization, but we show that they also compress more densely. We have developed a prototype framework for AST compression, which we have used to compress Java programs. Our generic implementation reduces the size of regular Java archives by a factor of 3 to 8 and improves on the best published Java-specific compression scheme by 5–50%.

In distributed and in embedded systems, the size of the application is frequently a critical measurement. In many cases, a smaller size brings huge, tangible benefits and special formats, known as wire-formats, are specifically developed to minimize the footprint of applications. In a typical wire-format, very complicated transformations are applied to yield the smallest possible size, and the compressed application must undergo a time-consuming decoding phase before its execution. This article argues that decoding is a very important contributor to the overall performance of a wire-format and belongs to the evaluation of new formats. The article presents a model that considers both the transmission time and the decompression time to qualify wire-formats. It validates experimentally this model and compares with it two experimental wire-formats for compiled Java applications and the Java archive format.