Jen-Chiun Lin

Secure and efficient group key management with shared key derivation

In many network applications, including distant learning, audio webcasting, video streaming, and online gaming, often a source has to send data to many receivers. IP multicasts and application-layer multicasts provide efficient and scalable one-to-many or many-to-many communications. A common secret key, the group key, shared by multiple users can be used to secure the information transmitted in the multicast communication channel. In this paper, a new group key management protocol is proposed to reduce the communication and computation overhead of group key rekeying caused by membership changes. With shared key derivation, new keys derivable by members themselves do not have to be encrypted or delivered by the server, and the performance of synchronous and asynchronous rekeying operations, including single join, single leave, and batch update, is thus improved. The proposed protocol is shown to be secure and immune to collusion attacks, and it outperforms the other comparable protocols from our analysis and simulation. The protocol is particularly efficient with binary key trees and asynchronous rekeying, and it can be tuned to meet different rekeying delay or key size requirements.

Efficient Group Key Management Protocol with One-Way Key Derivation

The growth of the Internet inspires lots of new network applications, and many of them are based on group communication models. Key trees are ideal for a group of users to efficiently and securely share a common secret key, the group key, which can encrypt transmitted data, or other session keys that protect group communication. An efficient group key management protocol is proposed for centralized dynamic groups, and one-way key derivation is integrated with key trees to reduce the communication overhead of rekeying operations. The server does not have to send new keys to those members who can derive the keys by themselves, and the total number of encrypted keys transmitted per rekeying operation becomes fewer. It is shown that the technique can be applied to both synchronous and asynchronous rekeying operations. The proposed protocol outperforms the other group key management protocols from our analysis and simulation, and is suitable for practical systems

HL7 middleware framework for healthcare information system

In this paper, a new middleware framework developed for the Health Information System (HIS) rightsizing project of National Taiwan University Hospital (NTUH) is proposed. The framework is basically a Service-Oriented Architecture (SOA). Challenges as formatting complex medical information as well as integrating heterogeneous systems in our hospital are addressed by introducing HL7 and Web services standard into our framework. Finally, the performance of a operating HIS based on our framework is analyzed and presented to evaluate the efficiency of our design. Keywords—HL7, Healthcare information system, web services, Service-oriented Architecture

Middleware based Inpatient Healthcare Information System

The paper presents a multi-tier, integrated, distributed, inpatient healthcare information system based on service oriented architecture (SOA) .NET environment in National Taiwan University Hospital (NTUH). The architecture and outcomes of the newly developed inpatient information system (IIS) platform are discussed in details. We also present mechanisms of integration as well as interoperability among the components and multi-database in IIS via health level seven (HL7) Middleware layer. The preliminary performance of the current operating IIS is evaluated and analyzed to verify the efficiency and effectiveness of the architecture we designed.

Trust-group-based authentication services for mobile ad hoc networks

In recent years, mobile ad hoc networks have received more attention, because of their easy deployment. However, the characteristics of mobile ad hoc networks are more prone to physical security threats than the wired network environments. Therefore, it has become a primary concern of securing mobile ad hoc networks. In this paper, we address the problem of authentication in mobile ad hoc networks. Public-key based mechanisms are ideal to provide the authentication services. Although this is already mature in a fixed network, providing public key based authentication is still very challenging in mobile ad-hoc networks because of shared wireless medium, energy constrains, dynamic network topology. Here, we present a more efficient public key management system, like self-organized scheme (S. Capkun et al., 2003), and include the concept of trust group for mobile ad hoc networks.

An effective output-oriented algorithm for low power multipartition architecture

Circuit partition for low power is a useful technique which reduces power dissipation by confining the switching activity to a subcircuit. In this paper, we propose an effective output-oriented partition algorithm for low power combinational logic circuits. We discuss the relationship between power dissipation, area complexity and input/output behavior of the combinational circuit rather than inspect its logic function. Experimental results show that our algorithm can obtain sizable power saving over a wide range of MCNC benchmarks.

A distributed key management protocol for dynamic groups

With the popularity of group-oriented applications, secure and efficient communication among all group members has become a major issue. We propose a distributed key management protocol for group members to share a secret group key, which can be used to protect shared information. The protocol manages the group key of a dynamic group, where members can freely join or leave, and each time the key is updated using two broadcast messages. The protocol algorithms provide group key secrecy, forward group key secrecy, and backward group key secrecy. The complexities of the group key computation time, the storage space for every member, and the total communication bandwidth to update the group key are approximately of logarithmic order of the group size, which make the protocol attractive for environments with less computation power and smaller storage.

SWARM: Secure Wireless Ad-hoc network Reliance Management

We use a clustering heuristic and adapt it for security requirements to provide a scalable authentication framework in the clustered ad hoc network. This novel approach can be used to achieve a variety of security objectives through the peer-to-peer authentication scheme. It scales well to large network size and does not require high node density and mobility speed like other distributed schemes. After forming clusters with a radius parameter, it allows separate authentication services to be employed for different physical conditions or security requirements into independent clusters, and each node in the network can obtain the topology of the clusters as well as the keys of all authentication services. The topology describes the trust relationship among clusters and is used to evaluate the trustworthiness of clusters. Finally, we evaluate the security scheme and simulate its performance on various configurations.

A constant size rekeying message framework for secure multicasting

We propose a new framework for key management to construct a secure multicasting environment. When rekeying, only one message needs to be generated, and the message size is a constant. Especially when the group size is large, our framework largely reduces the traffic in the network. Two solutions are given to carry out this framework, which are closed curve solution (CCS) and perpendicular space solution (PSS), respectively. One is based on a geometric approach and the other on a linear algebraic approach. Our framework is also compatible to other group communication protocols.

Synthesis of partition-codec architecture for low power and small area circuit design

Partitioning circuits for low power design at the logic level has been proposed as a very effective technique. However, the increased area of latches for duplicated input of multiple partitions always offsets the advantage. In this paper we propose a novel Partition-Codec Architecture to achieve low power and small area. The approach is based on evenly partition the output vectors by the corresponding input variables and re-assigning the output vectors of each partition to minimize the number of input vectors and Hamming distance of each partition, and one of the active decoders returns the value to its original output. Given a combinational circuit described by PLA, we develop a global-encoding algorithm, which consists of partition and re-assigning routines to synthesize the Parition-Codec Architecture to achieve low power and small area. Experimental results show that up to 69.5% power reduction, as well as 60.9% area decreased and average 35.7% power saving with 58.4% area reduction are achievable.