Abstract: In a transactional system, an atomic commitment protocol ensures that for any transaction, all data managers agree on the same outcome: commit or abort. A non-blocking atomic commitment protocol enables an outcome to be decided at every correct data manager despite the failure of others. It is well known that the famous Two Phase Commit protocol (2PC) is a blocking protocol, whereas the Three Phase Commit protocol (2PC) is a non-blocking protocol. Both protocols are centralized. We discuss a Decentralized Non-Blocking Atomic Commitment protocol, named DNB-AC. In the absence of failures, the DNB-AC protocol requires the same number of steps to commit than the 2PC protocol (three steps). Performance measures show that the DNB-AC protocol is significantly faster that the 3PC and in the case of a broadcast network, is almost as efficient as the 2PC. The DNB-AC protocol uses a uniform consensus protocol as a termination protocol. Using the recent results by Chandra and Toueg (1991) on solving consensus in an asynchronous system augmented with unreliable failure detectors, we give a precise characterization of the liveness of DNB-AC. We show that DNB-AC is non-blocking when a majority of data managers are correct, and the failure detector is in the class OS.

Abstract: A communication system uses a precise set of rules called a protocol, to define interactions among its entities. With advancing computer transmission and switching technology, communication systems are providing sophisticated services demanded by users over a wide area. Protocol standards include a very, large number of options to take care of different service possibilities and to please all the people involved in the Standards Committees. Consequently, protocols have become large and complex, and, therefore their design and analysis have become a formidable task. To cope with this problem, a variety of approaches to simplify the protocols have been proposed in the published literature, such as protocol projection, homomorphism, selective resolution, and many others. We have recently developed a new technique called protocol pruning. It reduces the complexity of the protocols by pruning them to keep only that part which is required for a specified subset of services. More importantly, it takes polynomial (rather than exponential) time and space in the size of the protocol specification. This makes the algorithm feasible for engineers to use for practical problems involving large and complex protocols. We describe the technique and discuss applications to synthesis of protocol converters/gateways, protocol conformance testing, and thinning for lightweight and high performance protocols. The technique could also be useful for protocol implementation, synthesis, validation, and verification. >

Abstract: This paper presents a locking protocol for secure databases which produces one-copy serializable and strict schedules. These schedules satisfy the multilevel security property-thus, the protocol is secure. The proposed protocol requires only two committed versions of the database; it executes read downs on the earlier committed version, while transactions accessing objects at their own level execute on the later committed version and are synchronized using strict 2PL. We discuss how the proposed protocol supports the execution of long-running transactions. The paper presents many useful details of snapshot maintenance for locking protocols in secure databases.

Abstract: Reasoning about key escrow protocols has increasingly become an important issue. The Escrowed Encryption Standard (EES) has been proposed as a US government standard for the encryption of unclassified telecommunications. One unique feature of this system is key escrow. The purpose of key escrow is to allow government access to session keys shared by EES devices. We develop a framework to formally specify and verify the correctness of key escrow protocols that we mechanize within the HOL theorem proving system. Our logic closely follows the logic, SVO, used for analyzing cryptographic protocols which was developed by Syverson and vanOorschot [13]. Using the HOL mechanization of SVO, we formally demonstrate the failure of the EES key escrow system by showing that it does not insure that the escrow agent receives correct information. This was previously shown experimentally [2]. Last, we offer an alternative escrow protocol and demonstrate its correctness.

Abstract: We present a packet multiple access protocol that is a hybrid of a pure CDMA protocol and an ALOHA random access protocol. The protocol utilizes the multireception capabilities of spread-spectrum communications together with the "statistical-multiplexing" capabilities of random access. We begin by presenting a multi-receiver random access protocol and analyze its throughput characteristics. We then develop collision resolution algorithms for the protocol that attempt to optimize its performance. These algorithms are analyzed through the use of simulation. We show that with proper choice of protocol parameters our protocol can handle all admissible traffic loads. We then propose a dynamic, adaptive extension to the protocol that uses limited feedback information to allow the protocol to vary its parameters based on the traffic load in the system. This dynamic, adaptive version of the protocol allows it to operate efficiently under a wide variety of traffic load conditions. At very light load conditions the protocol behaves as a pure random access protocol and at very high load it behaves as a pure fixed assignments protocol. Our protocol seems to be a good choice for providing random access on a satellite channel where propagation delays are long. It is also a natural choice for wireless transmission of very short (e.g., ATM) packets.

Abstract: A cryptographic protocol is an algorithm involving exchanges of encrypted information carried out by principals in a distributed environment. It is intended to produce secure communications, even if every message can be read by, or originate with, every principal. This paper gives a definitional HOL formalization of a “belief logic” based on the full Gong, Needham, and Yahalom [2] logic for analyzing whether protocols achieve desired communication conditions. This gives the “belief logic” a sound formal basis. The paper also sketches the algorithm for a possible HOL tactic automatically constructing proofs that protocols achieve desired communication conditions if they do achieve them.

Abstract: Media synchronization and freedom from starvation at destination devices are the two most important problems in a multimedia communication system. In order to solve these problems at the same time, this paper presents a protocol combining the scheduling scheme and the buffering scheme with underflow threshold (SBUF). In this protocol, by controlling the buffer sizes and modifying transmission schedule of the synchronizer synchronization can be achieved without synchronizing clocks during a connection. In this paper the algorithm of the protocol is described. The setting of the system parameters and network QOS to support the proposed protocol are also given in this paper. A simulation is performed for comparison of four synchronization schemes: scheduling schemes (with and without clock synchronization), marker scheme, and the proposed SBUF protocol. The results confirm that the proposed protocol guarantees satisfaction of QOS requirements and also performs better than the other schemes in terms of media synchronization and freedom from starvation at destination devices.

Abstract: Gemmell and Naor proposed a new protocol for unconditionally secure authentication of long messages. However Gehrmann showed that the proof of the security of the protocol was incorrect. Here we generalize the multiround protocol model. We prove the security of a 3-round protocol and give for this case a new easy implementable construction which has a key size close to the fundamental lower bound for even extremely long messages. Furthermore, we give a proof of a secure multiround protocol for an arbitrary number of rounds.

Abstract: Providing an application-tailored communication protocol increases the exploitation of service specific characteristics by any application. Especially, the configuration approach of communication protocols according to specified and requested application quality-of-service (QoS) requirements offers a highly flexible scenario to allow for a sufficient and appropriate protocol processing. The approaches of the function-based communication subsystem (F-CSS) and the dynamic configuration of protocols (Da CaPo) provide a basis for configuring specifically requested services. An important aspect for a future integration into the existing networking environment is the interoperability of configuration-based approaches. The case study presented evaluates the possibility of F-CSS and Da CaPo interoperability.

Abstract: The protocol engineering plays an important role in computer networks. Designing a protocol is a challenging activity because of the complexity of the rules defining the interaction between the communicating entities. At this point, formal approaches have been proposed: Analysis and Synthesis. The synthesis approach has the advantage of avoiding errors a priori and ensuring some desirable properties during the protocol design process. In this paper, we propose a relational protocol synthesis method. The method outcome is specifications of all protocol entities serving the different service access points, which are represented in R-net diagrams.

Abstract: We develop an asymmetric protocol for wireless communication in a step-by-step manner. We start with a very simple protocol and prove its correctness. Then we relax the assumptions of the simple protocol one by one, verifying the correctness of the protocol at each step as we relax the assumptions. This process is continued in a systematic manner until no assumptions are left. The novelty of the paper lies in the way the assumptions are relaxed without violating the correctness properties of the protocol while at the same time making the protocol efficient. The final result is a provably correct protocol which is also efficient for wireless channels.

Abstract: This paper presents a new approach for secure IN internetworking. Based on a threat analysis, an adequate cryptographic protocol is proposed to address the derived security concerns. The cryptographic protocol presented is based on the recently published standardization framework ISO/IEC CD11770-3.

Abstract: This paper presents CHtWNELS, a run-time system for network protocol processing. CHMNELS is especially intended and optimized for transport systems supporting multimedia applications on high-speed networks. Additionally to the traditional features of a run-time system like the scheduling of the processing of different protocols, the provision of dedicated facilities such as timer, buffer and mapping table libraries for protocol implementation and the support of the communication to adjacent protocol entities, network devices and user processes, CHANNELS enables the implementation of sophisticated protocols which require real-time and parallel processing capabilities, or dynamic protocol configuration support. CHANNELS is implemented in the C++ programming language and one prototype is embedded in the SUNIUNIX kernel.

Abstract: Group and multicast communication provide basic functions for many applications in distributed computing. In such a communication, the causal ordering property among messages should hold throughout distributed sites. Several communication protocols for this purpose have been designed so far. They are designed mostly under the strong assumptions: there is no loss of messages in the communication channel or the order of the messages is preserved or both. However, in WAN environment, it is desirable to design such a protocol without assuming these conditions from the efficiency point of view. In this paper, a protocol which provides the causal ordered broadcast in a non-FIFO network is investigated. The non-FIFO network is defined as the network in which there exists possibilities of loss and disorder of messages. The purpose of this paper is to perform experimental evaluations to a causal ordering protocol which is specially designed for a non-FIFO network. The protocol is implemented as a software system, and the performance evaluation of the system is done by experiments. In addition, a simple approximation of the queue length of the system is proposed. The applicability of the approximation also is investigated.

Abstract: The author describes a secure data communication method based on the CSMA/CD protocol in bidirectional star networks. A procedure for detecting packet collision while transmitting the jamming signal is required. The author assess two kinds of protocol, a CRV (code rule violation) protocol and a DR (delayed replying) protocol.