We deal with authentication / secrecy codes having unconditional security. Besides some new results for a "spoofing attack of order L", we give several constructions using finite incidence structures (designs, generalized quadrangles).

The development of Wireless Body Area Networks (WBANs) for wireless sensing and monitoring of a person's vital functions, is an enabler in providing better personal health care whilst enhancing the quality of life. A critical factor in the acceptance of WBANs is providing appropriate security and privacy protection of the wireless communication. This paper first describes a general health care platform and pinpoints the security challenges and requirements. Further it proposes and analyzes the CICADA-S protocol, a secure cross-layer protocol for WBANs. It is an extension of CICADA, which is a cross-layer protocol that handles both medium access and the routing of data in WBANs. The CICADA-S protocol is the first integrated solution that copes with threats that occur in this mobile medical monitoring scenario. It is shown that the integration of key management and secure, privacy preserving communication techniques within the CICADA-S protocol has low impact on the power consumption and throughput.

Abstract. We investigate authentication codes with splitting, using the mathematical model introduced by Simmons. Besides an overview of the existing bounds, we obtain some new bounds for the probability of deception of the transmitter/ receiver in case of an impersonation or substitution game. We also prove some new bounds for a "spoofing attack of order L." Further, we give several new constructions for authentication/secrecy codes with splitting, derived from finite incidence structures such as partial geometries and affine resolvable designs. In some of these codes the bounds are attained with equality.

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It is the aim to deal with codes having unconditional security, which means that the security is independent of the computing power. .4nalogously to the theory of unconditional secrecy due t o Shannon (121, Simmons developed a theory of unconditional authentication [lo]. In this paper we give some new bounds and constructions for authentication/secrecy codes with splitting. Consider a transmitter who wants to communicate a source to a remote receiver by sending messages through an imperfect communication channel. Then there are two