Fingerprinting embeds a secret message into a cover message. In media fingerprinting, the secret is usually a copyright notice and the cover a digital image. Fingerprinting an object discourages intellectual property theft, or when such theft has occurred, allows us to prove ownership. The Software Fingerprinting problem can be described as follows. Embed a structure W into a program P such that: W can be reliably located and extracted from P even after P has been subjected to code transformations such as translation, optimization and obfuscation; W is stealthy; W has a high data rate; embedding W into P does not adversely affect the performance of P ; and W has a mathematical property that allows us to argue that its presence in P is the result of deliberate actions. In this article, we describe a software fingerprinting technique in which a dynamic graph fingerprint is stored in the execution state of a program. Because of the hardness of pointer alias analysis such fingerprints are difficult to attack automatically.

Jcon is a new, full-featured, Java-based implementation of the Icon programming language. The compiler, written in Icon, generates an intermediate representation that is optimized and then used to produce classfiles of Java bytecode. A four-chunk control-flow model handles goal-directed evaluation and produces constructs not expressible as Java code. The runtime system, written in Java, finds object-oriented programming a great advantage in implementing a dynamically typed language, with method calls replacing many conditional tests. An all-encompassing descriptor class supports values, references, and suspended operations. The procedure call interface is simple and incurs overhead for generator support only when actually needed. Performance is somewhat disappointing, and some limitations are annoying, but in general Java provides a good implementation platform. Copyright © 2000 John Wiley & Sons, Ltd.

Abstract When graphics input/output capabilities are added to a programming language originally designed with a text stream input/output model, various design decisions affect the ease with which the graphics facilities are learned and used by applications programmers. In adding window system facilities to the Icon programming language, some design decisions were made very differently from the conventional wisdom, resulting in substantial benefits for programmers. In addition, some pre‐existing Icon language features have proved to be useful in graphics programming.

Abstract Two key features in the Icon programming language are tables and sets. An Icon program may use one large set or table, or thousands of small ones. To improve space and time performance for these diverse uses, their hashed data structures were reimplemented to dynamically resize during execution, reducing the minimum space requirement and achieving constant‐time access to any element for virtually any size set or table. The implementation is adapted from Per‐Åke Larson's dynamic hashing technique by using well‐known base‐2 arithmetic techniques to decrease the space required for small tables without degrading the performance of large tables. Also presented are techniques to prevent dynamic hashing from interfering with other Icon language features. Performance measurements are included to support the results.

SR is a language for programming distributed systems ranging from operating systems to application programs. On the basis of our experience with the initial version, the language has evolved considerably. In this paper we describe the current version of SR and give an overview of its implementation. The main language constructs are still resources and operations. Resources encapsulate processes and variables that they share; operations provide the primary mechanism for process interaction. One way in which SR has changed is that both resources and processes are now created dynamically. Another change is that inheritance is supported. A third change is that the mechanisms for operation invocation—call and send—and operation implementation—proc and in—have been extended and integrated. Consequently, all of local and remote procedure call, rendezvous, dynamic process creation, asynchronous message passing, multicast, and semaphores are supported. We have found this flexibility to be very useful for distributed programming. Moreover, by basing SR on a small number of well-integrated concepts, the language has proved easy to learn and use, and it has a reasonably efficient implementation.