The notion of Integrated Modular Avionics (IMA) refers to inter-connected pieces of avionics equipment supported by a wired technology, with stringent reliability and safety requirements. If the inter-connecting wires are physically secured so that a malicious user cannot access them directly, then this enforces (at least partially) the security of the network. However, substituting the wired network with a wireless network - which in this context is referred to as an Avionics Wireless Network (AWN) - brings a number of new challenges related to assurance, reliability, and security. The AWN thus has to ensure that it provides at least the required security and safety levels offered by the equivalent wired network. Providing a wired-equivalent security for a communication channel requires the setting up of a strong, secure (encrypted) channel between the entities that are connected to the AWN. In this paper, we propose three approaches to establish such a secure channel based on (i) pre-shared keys, (ii) trusted key distribution, and (iii) key-sharing protocols. For each of these approaches, we present two representative protocol variants. These protocols are then implemented as part of a demo AWN and they are then compared based on performance measurements. Most importantly, we have evaluated these protocols based on security and operational requirements that we define in this paper for an AWN.
Security and the general deployment of AWNs based on wireless-as-a-comm-link have been analyzed in @cite_17 , which discusses the security and trust challenges faced by AWNs. Beside this, a crucial component of the security of aircraft devices is the trusted boot process discussed in @cite_7 . The security, trust and assurance issues related to bringing a user device into an aircraft network are evaluated in @cite_12 .
@cite_12 @cite_7 @cite_17
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Avionics networks have a set of stringent reliability and safety requirements. In existing deployments, most of these networks are based on wired technology which provides a high degree of reliability and safety. Furthermore, it simplifies the security management of the network since certain assumptions, including an inability for an attacker to access the network, can be safely made. The proposal for having an Avionics Wireless Network (AWN), currently being developed by multiple aerospace working groups, promises reduction in the complexity of electrical wiring harness design and fabrication, reduction in wiring weight, increased configurability, and potential monitoring of otherwise inaccessible moving or rotating aircraft parts. While providing these benefits, the AWN must ensure that it provides, at a minimum, equivalent levels of safety to those offered by the wired network. Substituting the wired network with a wireless network, even for a specific set of well-defined and non-critical tasks, brings a whole set of new challenges related to assurance, reliability, and security. In this paper, we discuss the security and trust challenges an AWN deployment might face, along with highlighting potential directions for solutions. Furthermore, as a case study we will elaborate on AWN deployment variants especially the wireless as a comm-link. Finally, the paper makes suggestions that set the agenda for security, reliability and trust work that could, if successful, provide an AWN system meeting the required safety standards. Integrated Modular Avionics (IMA) in existing deployments is a collection of inter-connected avionics equipment supported by wired technology, with stringent reliability and safety requirements. If the inter-connecting wires are physically secured so that a malicious user cannot access them directly, then this simplifies the security management of the network. However, substituting the wired network with a wireless network - also referred to as an Avionics Wireless Network (AWN) - brings a set of new challenges related to assurance, reliability, and security; even for a specific set of well-defined and non-critical tasks. The AWN has to ensure that it provides at a minimum the existing required levels of safety offered by the equivalent wired network. These challenges are underpinned by a necessity to boot the AWN to a secure and trusted state, before it can be used to bridge different parts of the IMA in an aircraft. In this paper, we discuss the security and trust challenges an AWN boot process might face, along with highlighting a potential solution. Finally, the paper evaluates the proposed validation solution that meets the stated security requirements, based on the security challenges discussed. Due to the broadcast nature of radio propagation, the wireless air interface is open and accessible to both authorized and illegitimate users. This completely differs from a wired network, where communicating devices are physically connected through cables and a node without direct association is unable to access the network for illicit activities. The open communications environment makes wireless transmissions more vulnerable than wired communications to malicious attacks, including both the passive eavesdropping for data interception and the active jamming for disrupting legitimate transmissions. Therefore, this paper is motivated to examine the security vulnerabilities and threats imposed by the inherent open nature of wireless communications and to devise efficient defense mechanisms for improving the wireless network security. We first summarize the security requirements of wireless networks, including their authenticity, confidentiality, integrity, and availability issues. Next, a comprehensive overview of security attacks encountered in wireless networks is presented in view of the network protocol architecture, where the potential security threats are discussed at each protocol layer. We also provide a survey of the existing security protocols and algorithms that are adopted in the existing wireless network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term evolution (LTE) systems. Then, we discuss the state of the art in physical-layer security, which is an emerging technique of securing the open communications environment against eavesdropping attacks at the physical layer. Several physical-layer security techniques are reviewed and compared, including information-theoretic security, artificial-noise-aided security, security-oriented beamforming, diversity-assisted security, and physical-layer key generation approaches. Since a jammer emitting radio signals can readily interfere with the legitimate wireless users, we also introduce the family of various jamming attacks and their countermeasures, including the constant jammer, intermittent jammer, reactive jammer, adaptive jammer, and intelligent jammer. Additionally, we discuss the integration of physical-layer security into existing authentication and cryptography mechanisms for further securing wireless networks. Finally, some technical challenges which remain unresolved at the time of writing are summarized and the future trends in wireless security are discussed. Secure Device Pairing is the bootstrapping of secure communication between two previously unassociated devices over a wireless channel. The human-imperceptible nature of wireless communication, lack of any prior security context, and absence of a common trust infrastructure open the door for Man-in-the-Middle (aka Evil Twin) attacks. A number of methods have been proposed to mitigate these attacks, each requiring user assistance in authenticating information exchanged over the wireless channel via some human-perceptible auxiliary channels, e.g., visual, acoustic or tactile. In this paper, we present results of the first comprehensive and comparative study of eleven notable secure device pairing methods. Usability measures include: task performance times, ratings on System Usability Scale (SUS), task completion rates, and perceived security. Study subjects were controlled for age, gender and prior experience with device pairing. We present overall results and identify problematic methods for certain classes of users as well as methods best-suited for various device configurations.