Gianluca Caparra

Energy-based anchor node selection for IoT physical layer authentication

We consider a cellular Internet of things (CIoT) network where many source nodes aim at exchanging messages with a single concentrator node. To this end, they are assisted by anchor nodes that are trusted and securely connected with the concentrator node. In this context, we aim at providing a message authentication scheme based on the characteristics of the channel between the source nodes and the anchor nodes. According to this approach, the anchor nodes estimate the channel to source nodes in an initially externally authenticated fashion, while forthcoming messages are authenticated by comparing the current channel estimate with the initial estimate. Moreover, assuming that the anchor nodes have a limited energy availability, we derive suitable scheduling policies for the activation of the anchor nodes for authentication purposes. In particular, we aim at maximizing the anchors lifespan while guaranteeing given false alarm and missed detection probabilities of the authentication process. The performance of the proposed authentication protocols is evaluated in a typical CIoT scenario.

Evaluating the security of one-way key chains in TESLA-based GNSS Navigation Message Authentication schemes

In the proposals for Global Navigation Satellite Systems (GNSS) Navigation Message Authentication (NMA) that are based on adapting the Timed Efficient Stream Loss-Tolerant Authentication (TESLA) protocol, the length of the one-time keys is limited (e.g. to 80 bits) by the low transmission rate. As a consequence, the hash function that is used to build the one-way key chain is constructed having a longer, secure hash function (e.g. SHA-256), preceded by a time-varying yet deterministic padding of the input and followed by a truncation of the output. We evaluate the impact of this construction on the collision resistance of the resulting hash function and of the whole chain, and show that with current proposed parameters, combined with the use of efficient hashing hardware, it can lead to a feasible attack with significant collision probability. The collision can be leveraged to mount a long lasting spoofing attack, where the victim receiver accepts all the one time keys and the navigation messages transmitted by the attacker as authentic. We conclude by suggesting possible modifications to make TESLA-based NMA more robust to such attacks.

A key management architecture for GNSS open service Navigation Message Authentication

Navigation Message Authentication (NMA) is a necessary security provision in GNSS open service, considering that more and more infrastructures rely on civilian GNSS signals, and several cryptographic mechanisms have been proposed to implement it. Most solutions adapt existing protocols to the specific requirement and constraints of the GNSS scenario, which is inherently one-way and asymmetric, and hence make use of asymmetric cryptography. However, no similar proposal has yet been made for the provision of key management services (distribution, upgrade, revocation), which are crucial for the security of any cryptographic mechanism.

An autonomous GNSS anti-spoofing technique

In recent years, the problem of Position, Navigation and Timing (PNT) resiliency has received significant attention due to an increasing awareness on threats and the vulnerability of the current GNSS signals. Several proposed solutions make uses of cryptography to protect against spoofing. A limitation of cryptographic techniques is that they introduce a communication and processing computation overhead and may impact the performance in terms of availability and continuity for GNSS users. This paper introduces autonomous non cryptographic antispoofing mechanisms, that exploit semi-codeless receiver techniques to detect spoofing for signals with a component making use of spreading code encryption.