Abstract
CANopen is a field level communication protocol for industrial automation distributed applications. The acceptance of CANopen is already widespread and continues growing, because it offers not only all the well known features of CAN for real-time communication, but also a powerful set of higher level Application Layer services. These services implement an object-oriented distributed environment for simplified system integration, but still they allow for a very high level of communication efficiency. Often, sensors and actuators have to be placed at geographically remote locations, at considerable distances from the processor(s) running a control application. When this is the case, a possible solution, that is gaining increasing popularity, is to use an autonomous I/O module, located close to the sensors and actuators, that provides the application with an interface to these devices. For this to be possible, the application must be distributed between the remote I/O module and the local processor(s) using a communication network to allow the different parts to cooperate. This work is centred on the development of an I/O module of the type previously described, based on the SAB-C167CR-LM chip from SIEMENS. The device is able, on one hand, to interface with sensors and actuators using digital signals and, on the other hand, to communicate using the CANopen protocol. In other words, the I/O module makes sensors and actuators accessible via the CAN bus, using the CANopen protocol. The objective is to show that CANopen can be implemented over new hardware platforms, in minimum time, with satisfactory results. It is shown that CANopen provides a systems-integrator-friendly object-oriented environment and that for this reason, the CANopen Communication Profile greatly simplifies the implementation of distributed applications in CAN based systems. Furthermore, CANopen also provides flexible realtime data transfer mechanisms that are able to meet time-critical constraints and, therefore,make CANopen a good solution for distributed control environments.

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We extend the generic framework of reproducibility for reuse of randomness in multi-recipient encryption schemes as proposed by Bellare et al. (PKC 2003). A new notion of weak reproducibility captures not only encryption schemes which are (fully) reproducible under the criteria given in the previous work, but also a class of efficient schemes which can only be used in the single message setting. In particular, we are able to capture the single message schemes suggested by Kurosawa (PKC 2002), which are more efficient than the direct adaptation of the multiple message schemes studied by Bellare et al. Our study of randomness reuse in key encapsulation mechanisms provides an additional argument for the relevance of these results: by taking advantage of our weak reproducibility notion, we are able to generalise and improve multi-recipient KEM constructions found in literature. We also propose an efficient multi-recipient KEM provably secure in the standard model and conclude the paper by proposing a notion of direct reproducibility which enables tighter security reductions.

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We introduce the concept of identity based key encapsulation to multiple parties (mID-KEM), and define a security model for it. This concept is the identity based analogue of public key KEM to multiple parties. We also analyse possible mID-KEM constructions, and propose an efficient scheme based on bilinear pairings. We prove our scheme secure in the random oracle model under the Gap Bilinear Diffie-Hellman assumption.