We investigate the effects of DoS (Denial of Service) attacks in wireless ad hoc networks using simulations, concentrating on the problem of energy availability. Our results show that the damages due to the DoS attack may quite different with those in wired networks: First, the nodes along the transmission route mostly suffer damages rather than the victim node itself. Second, if the mobile nodes are crowded and close together, the damage becomes more severe. Lastly, if the nodes have random mobility, the attacker itself consumes more energy.

Most network systems provide an authentication mechanism based on a user identification number and a password. In such systems, it is easy to obtain a user's password using a sniffer program with illegal eavesdropping. The one-time password method and the challenge-response method are useful authentication schemes that protect a user's password against eavesdropping. In client/server environments, the one-time password scheme using time is especially useful because it solves the synchronization problem. However, it has a problem of time-slippage, and this problem causes the authentication to be failed. In this paper, we propose an effective one-time password algorithm, which solves the time-slippage problem through the use of 1-bit information, which denotes the duration in which the authentication could be failed because of time-slippage. This algorithm can be added easily and quickly to current one-time password systems using time without requiring any change of protocols.

Interoperability is one of the fundamental functions of a home network because such networks must support many different types of devices and services. Interoperability can be realized by converting messages among different middleware with rules. However, it is very difficult to define common rules to accommodate all differences among various middleware. In addition, most interoperability approaches only address the conversion of the message format and schema, and occasionally these are not enough for a semantic conversion. In this paper, we propose a systematic approach to solve the interoperability problem. For this, we classify three interoperability types, i.e., schema, profile, and procedure, and define the rules for each type. We called this interoperability scheme the Multiple stage Approach for Home network Interoperability (MAHI). In this paper, we present the design and implementation of MAHI for a three-stage conversion process. Finally, we illustrate some experimental and quantitative results. In the experiments, MAHI can provide efficient interoperability among different middleware and MAHI will be a method to deal with a complex home network interoperability.