How did we get from a world where cookies were something you ate and where "nontechies" were unaware of "Netscape cookies" to a world where cookies are a hot-button privacy issue for many computer users? This article describes how HTTP "cookies" work and how Netscape's original specification evolved into an IETF Proposed Standard. I also offer a personal perspective on how what began as a straightforward technical specification turned into a political flashpoint when it tried to address nontechnical issues such as privacy.

This paper introduces a cryptographic engine, Janus, which assists clients in establishing and maintaining secure and pseudonymous relationships with multiple servers. The setting is such that clients reside on a particular subnet (e.g., corporate intranet, ISP) and the servers reside anywhere on the Internet. The Janus engine allows each client-server relationship to use either weak or strong authentication on each interaction. At the same time, each interaction preserves privacy by neither revealing a clients true identity (except for the subnet) nor the set of servers with which a particular client interacts. Furthermore, clients do not need any secure long-term memory, enabling scalability and mobility. The interaction model extends to allow servers to send data back to clients via e-mail at a later date. Hence, our results complement the functionality of current network anonymity tools and remailers. The paper also describes the design and implementation of the Lucent Personalized Web Assistant (LPWA), which is a practical system that provides secure and pseudonymous relations with multiple servers on the Internet. LPWA employs the Janus function to generate site-specific personæ, which consist of alias usernames, passwords, and e-mail addresses.

We present a new approach for conformance testing of protocols specified as a collection of communicating finite state machines (FSMs). Our approach uses a guided random walk procedure. This procedure attempts to cover all transitions in the component FSMs. We also introduce the concept of observers that check some aspect of protocol behavior. We present the result of applying our method to two example protocols: full-duplex alternating bit protocol and the ATM-adaptation-layer-convergence protocol. Applying our procedure to the ATM adaptation layer, 99% of component FSMs edges can be covered in a test with 11692 input steps. Previous approaches cannot do conformance test generation for standard protocols (such as asynchronous transfer mode (ATM) adaptation layer) specified as a collection of communicating FSMs.

This paper presents the design and analysis of three reliable multicast transport protocols for high speed networks. The novelty of these protocols lies in the technique used in combining the acknowledgments of individual destinations along the underlying multicast tree to prevent acknowledgement implosion and in the technique used in preventing unnecessary retransmission by performing local multicasts. These protocols use the periodic exchange of complete state information between the source and the destinations and a block-based Selective Repeat retransmission scheme to improve the overall performance in a high speed networking environment. Performance of each protocol is analyzed in terms of throughput, end-to-end delay, buffer requirement, acknowledgment traffic and retransmission traffic. Based on this analysis and the complexity of implementation, one of the three protocols is recommended for reliable multicasting in high speed networks.>

The authors describe efforts to develop the Q.931 protocol software for the 5ESS Central Office Switch. Q.931 is a layer-3 message-based, user/network interface protocol for the integrated services digital network (ISDN). The approach uses a single formal specification written in the Augmented Protocol Specification Language to model the 1.931 protocol as a set of communicating extended finite state machines. From this specification, tools validate the protocol and generate the bulk of a C language implementation. The authors successfully integrated this code, along with other handwritten code, into a working system in the lab. Their results demonstrate that protocol tools can be used effectively to develop high quality protocol software quickly from formal specifications.>

An approach for conformance testing of protocols specified as a collection of communicating finite state machines (FSMs) with two parts, pruning and a guided random walk procedure, is presented. First the protocol is pruned to various sets of machines; each set provides only one service. This significantly reduces the test sequence length. Then a guided random walk procedure that attempts to cover all transitions in the component FSMs is used. The results of applying the procedure to the full-duplex alternating bit protocol and the asynchronous transfer mode (ATM) adaptation layer convergence protocol are presented. For the ATM adaptation layer, 99% of component FSMs' edges can be covered in a test with 11692 input steps. Previous approaches cannot generate conformance tests for standard protocols (such as ATM adaptation layer) specified as a collection of communicating FSMs.>

A systematic procedure that takes exponential time to synthesize protocol converters from formal specifications is presented. The algorithm proceeds in two steps: compute the largest common subset of services provided by the two mismatched protocols, and reduce the converter, retaining common services, without traversing the entire machine that represents the composition of the two mismatched protocols. In a number of cases, the converter can be constructed by a memoryless translation of messages from one protocol to another. Conditions under which such stateless conversion is possible are given. Two examples are presented to illustrate the techniques. In the first example, a converter that interconnects a half-duplex protocol with a full-duplex protocol from their formal specifications is computed. In the second example, the polynomial procedure is applied to computation of a converter for interconnecting the SNR and TCP protocols.>