Jean Mayo

ThreadMentor: a pedagogical tool for multithreaded programming

ThreadMentor is a multiplatform pedagogical tool designed to ease the difficulty in teaching and learning multithreaded programming. It consists of a C++ class library and a visualization system. The class library supports many thread management functions and synchronization primitives in an object-oriented way, and the visualization system is activated automatically by a user program and shows the inner working of every thread and every synchronization primitive on-the-fly. Events can also be saved for playback. In this way, students will be able to visualize the dynamic behavior of a threaded program and the interaction among threads and synchronization primitives.

A secure unrestricted advanced systems laboratory

We present the design of a systems laboratory intended for advanced undergraduates and graduate students. The laboratory provides an environment in which students are given complete (root) control of systems with essentially unrestricted access to the Internet. This is achieved without jeopardizing the security of the departmental network of which the laboratory is a part. Students in the laboratory are also given a secure environment in which to do their work. Such a laboratory is most valuable in advanced courses in operating systems and networks in which students implement and evaluate algorithms and policies subjected to real workloads. It is also valuable as a facility for research on systems and network topics, providing an open, yet safe, environment in which to work.

Global predicates in rough real time

Evaluation of predicates on the state of a distributed system is complicated by the lack of either a common clock or common memory. In these systems, message passing is often used to order local events globally. This leads to a partial, causal ordering of system events. Predicate evaluation algorithms based on this causal ordering generally cannot determine if an unstable predicate was true at some instant of real time without freezing the underlying application. They only determine whether or not the predicate could have occurred. This ordering is sufficient for evaluating stable predicates, but algorithms based on it require a good deal of message passing. We present two algorithms which conclusively evaluate both stable and a restricted class of unstable predicates for a given execution. The algorithms are based on the use of roughly synchronized clocks. We present an algorithm for scheduled evaluation as well as a centralized detection algorithm.

MuON: epidemic based mutual anonymity

A mutually anonymous service hides the identity of a client from the service provider and vice-versa. Providing mutual anonymity usually requires a large number of participants. While peer-to-peer (P2P) networks are capable of recruiting a large number of participants, reliable anonymous communication in these architectures, with low bandwidth usage, still needs further investigation. This paper presents MuON, a protocol to achieve mutual anonymity in unstructured P2P networks. MuON leverages epidemic-style data dissemination to deal with the high churn (changes in system membership) characteristic of unstructured P2P networks. The results from our security analysis and simulation show that MuON provides mutual anonymity over unstructured P2P networks while maintaining predictable latencies, high reliability, and low communication overhead

MuON: Epidemic based mutual anonymity in unstructured P2P networks

A mutual anonymity system enables communication between a client and a service provider without revealing their identities. In general, the anonymity guarantees made by the protocol are enhanced when a large number of participants are recruited into the anonymity system. Peer-to-peer (P2P) systems are able to attract a large number of nodes and hence are highly suitable for anonymity systems. However, the churn (changes in system membership) within P2P networks, poses a significant challenge for low-bandwidth reliable anonymous communication in these networks. This paper presents MuON, a protocol to achieve mutual anonymity in unstructured P2P networks. MuON leverages epidemic-style data dissemination to deal with churn. Simulation results and security analysis indicate that MuON provides mutual anonymity in networks with high churn, while maintaining predictable latencies, high reliability, and low communication overhead.

A general model for detecting distributed termination in dynamic systems

Summary form only given. A symmetric algorithm is proposed for detecting distributed termination in a dynamic system with asynchronous communication networks. Correctness of the algorithm is proven. In the system, active processes may create new processes or accept outside processes to join the basic computation. No processes can be destroyed or leave the system until the computation terminates. The network model exploited in the algorithm is a combination of a logical ring and computation trees. It is more general and especially suitable for the applications on Internet networks. The algorithm is more efficient than those in previous works in terms of control messages used in the detection protocol.

ECvisual: a visualization tool for elliptic curve based ciphers

This paper describes a visualization tool ECvisual that helps students understand and instructors teach elliptic curve based ciphers. This tool permits the user to visualize elliptic curves over the real field and over a finite field of prime order, perform arithmetic operations, do encryption and decryption, and convert plaintext to a point on an elliptic curve. The demo mode of ECvisual can be used for classroom presentation and self-study. With the practice mode, the user may go through steps in finite field computations, encryption, decryption and plaintext conversion. The user may compute the output for each operation check each answer for correctness. This helps students understand the primitive operations and how they are used in an elliptic curve cipher. The opportunity for self-study provides an instructor greater flexibility in selecting a lecture pace for this detail-filled material. Classroom evaluation was positive and very encouraging.

A communication library to support concurrent programming courses

A number of communication libraries have been written to support concurrent programming. For a variety of reasons, these libraries generally are not well-suited for use in undergraduate courses. We have written a communication library uniquely tailored to an academic environment. The library provides two levels of communication abstraction (topology and channel) and supports communication among threads, processes on the same machine, and processes on different machines, via a unified interface. The routines facilitate controlled message loss along channels and can be integrated with an existing graphical tool that supports visualization of the communication that occurs. An editor has been developed for automatic code generation for arbitrary topologies via a graphical interface. All these tools run over Solaris, Linux, and Windows.

A secure networked laboratory for kernel programming

Recently, several flavours of UNIX have appeared which run on inexpensive personal computers. Further, the source code for these operating systems is freely available. This makes offering courses that include realistic kernel programming feasible in an academic environment. However, root access is required in order to modify a systems kernel. This poses a potential security threat both to other systems on the network and to other users of a single machine. This paper presents a lab design which securely integrates machines with untrusted users acting as root into a secured network, and which securely allows multiple users root access to the same machine.

RSAvisual: a visualization tool for the RSA cipher

This paper describes a visualization tool RSAvisual that helps students learn and instructors teach the RSA cipher. This tool permits the user to visualize the steps of the RSA cipher, do encryption and decryption, learn simple factorization algorithms, and perform some elementary attacks. The demo mode of RSAvisual can be used for classroom presentation and self-study. With the practice mode, the user may go through steps in encryption, decryption, the Extended Euclidean algorithm, two simple factorization algorithms and three elementary attacks. The user may compute the output of each operation and check for correctness. This helps students learn the primitive operations and how they are used in the RSA cipher. The opportunity for self-study provides an instructor with greater flexibility in selecting a lecture pace for the detailed materials. Classroom evaluation was positive and very encouraging.