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Process algebras are convenient formalisms to develop specifications stepwise. This can be done with the help of partially defined states in a specification. When refining the specification, new transitions are added to partially defined states. At every step, it is verified with the help of special preorders, refinement relations, that the step leads towards a desired goal. This approach has already been introduced in the case, where the verification is based on weak bisimulation equivalence. We show in this article that refinement relations can also be developed in decorated trace semantics. Moreover, the intuitive picture seems to be simpler in trace-based than in bisimulationbased semantics. The algorithms to compute the new refinement relations are exponential in the worst case, but behave quite well in practical cases.

Control signaling messages in Mobile IPv6 are mainly used to inform the home agent (HA) and the correspondent node (CN) about the mobile node's (MN's) new address when its network attachment point is changed. In order to prevent various security attacks, these messages must be protected. In the current standard, the control signaling messages between a HA and a MN are authenticated using IPSec, often with IKEv2 and X.509 certificates. Control signaling messages between a MN and a CN are currently protected by an effective but insecure protocol, known as Return Routability. Using IBE (Identity-Based Encryption) for authenticating control signaling messages requires more processing power but significant security enhancements are achieved. The current protocols for protecting control signaling messages are outlined in this paper. Proposed approaches for implementing IBE-authentication between a MN and a HA as well as between a MN and a CN are presented. Environments where the MN and the CN use the same Public Key Generator (PKG) as well as environments where they use different PKGs are taken into account. Finally, the performance of some proposed signaling protocols is estimated. An overview of IBE is given and the elements and operations needed to set up an IBE infrastructure are described in an appendix.

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Host Identity Protocol (HIP) gives cryptographically verifiable identities to hosts. These identities are based on public key cryptography and consist of public and private keys. Public keys can be stored, together with corresponding IP addresses, in DNS servers. When entities are negotiating on a HIP connection, messages are signed with private keys and verified with public keys. Even if this system is quite secure, there is some vulnerability concerning the authenticity of public keys. The authors examine some possibilities to derive trust in public parameters. These are DNSSEC and public key certificates (PKI). Especially, the authors examine how to implement certificate handling and what is the time complexity of using and verifying certificates in the HIP Base Exchange. It turned out that certificates delayed the HIP Base Exchange only some milliseconds compared to the case where certificates are not used. In the latter part of our article the authors analyze four proposed HIP multicast models and how they could use certificates. There are differences in the models how many times the Base Exchange is performed and to what extent existing HIP specification standards must be modified.