With the development of solutions like 6LoWPAN, the implementation of IP technology in sensor devices is already a reality. Therefore, sensors can be natively integrated in the Internet, becoming globally addressable by any other Internet-connected party. Despite the huge potential of this approach, it also gives place to new threats, being one of the most critical ones the effective protection of the information gathered by sensors from unauthorised remote access attempts. A suitable solution to address this issue is the Ladon security protocol, which provides resource-deprived devices with end-to-end authentication, authorisation and key establishment mechanisms. Once the critical security issue has been solved, additional concerns arise. Specially remarkable is the protection of user privacy in order to prevent potential eavesdroppers from tracking users’ access trends and obtaining behavioural patterns. In this regard, authentication and authorisation processes deserve an special consideration, since they imply conveying user identity-related information to the targeted services. In this paper, we present a privacy-enhanced Ladon protocol by integrating the original protocol with the PrivaKERB user privacy framework for Kerberos. Due to the severe resource limitations that characterise the targeted environments, a performance evaluation of the proposed solution is carried out in order to prove that it meets the performance requirements of the considered environments in terms of energy cost and additional delay for each secure session establishment. The obtained results show that privacy-enhanced Ladon is a secure and efficient solution to implement privacy-supporting authentication and authorisation processes in resource-deprived environments.

The upcoming development of the Internet of Things (IoT) envisions IP-enabled pacemakers and ICDs, giving place to a completely new scenario in the field of remote monitoring of patients implanted with these devices. Apart from the costs saved thanks to the reduction of in-clinic visits, this new approach will help improving the quality of life of chronic patients that depend on such devices. However, this scenario cannot be conceived without an effective mechanism to protect the privacy of the health information collected by implanted sensors, understanding privacy as the capacity to determine when, how and to what extent information is communicated to others. In this paper, we show how the Ladon authentication, authorization and key establishment protocol can be successfully applied to achieve this purpose. The Ladon protocol is based on Kerberos, but appropriately modified and extended to support independence of clock synchronization and authorization functionalities. In order to demonstrate the feasibility of introducing Ladon in the targeted scenarios, a prototype implementation based on general purpose sensors has been developed. The obtained results show that the performance penalty introduced by the protocol in terms of energy and time consumption is negligible.

IP-enabled sensors can be globally addressable by any Internet-connected entity, and therefore, their protection presents different challenges than that of traditional sensors, as they are subject to any potential attacker in the Internet. For this reason, specific security protocols must be developed to address the security requirements of IP-enabled sensors. An interesting approach to achieve this aim is the Ladon security protocol, which allows resource-deprived devices to efficiently implement end-to-end authentication, authorisation and key establishment mechanisms. However, in so limited environments such as sensor networks, not only efficient protocols must be defined, but they must also be optimally parameterised. This paper constitutes a step forward in this direction. First, a state transition model of the Ladon protocol is presented to analytically describe its behaviour. Then, this model is used to select the most effective parameterisation of the protocol in terms of message retransmissions and execution of cryptographic operations. The obtained results show that the selected parameterisation allows maximising the probability of a successful secure session establishment, while keeping the overhead introduced by the protocol low. Additionally, the performance comparison carried out shows that Ladon outperforms alternative approaches to achieve the same objective in terms of message transmission and reception operations.