With the growing use of underwater acoustic communications (UWAC) for both industrial and military operations, there is a need to ensure communication security. A particular challenge is represented by underwater acoustic networks (UWANs), which are often left unattended over long periods of time. Currently, due to the physical and performance limitations, the UWAC packets rarely include encryption, leaving the UWAN exposed to external attacks faking legitimate messages. In this paper, we propose a new algorithm for message authentication in a UWAN setting. We begin by observing that, due to the strong spatial dependency of the underwater acoustic channel, an attacker can attempt to mimic the channel associated with the legitimate transmitter only for a small set of receivers, typically just for a single one. Taking this into account, our scheme relies on trusted nodes that independently help a sink node in the authentication process. For each incoming packet, the sink fuses beliefs evaluated by the trusted nodes to reach an authentication decision. These beliefs are based on the estimated statistics of the channel parameters, which are chosen to be the most sensitive to the transmitter-receiver displacement. Our simulation results show accurate identification of an attacker’s packet. We also report results from a sea experiment demonstrating the effectiveness of our approach.
User authentication has been addressed by the so-called physical layer security by exploiting the channel coherence, i.e., messages going from the same source to the same destination are subject to the same channel, whereas a message coming from a fake source located in a different position will be subject to a different channel, which can be estimated at the destination (see @cite_27 for a survey). Various channel features have been considered in this context. For example, in wireless radio systems, the power level was considered in @cite_33 @cite_8 @cite_38 , the impulse response of a wideband channel in @cite_0 @cite_19 @cite_6 @cite_4 @cite_13 , the frequency response of an OFDM transmission in @cite_18 , the power spectral densities in @cite_10 , and the time series of the received signal strength in a data acknowledgment packet exchange in @cite_7 .
@cite_38 @cite_18 @cite_4 @cite_33 @cite_7 @cite_8 @cite_10 @cite_6 @cite_0 @cite_19 @cite_27 @cite_13
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Wireless networks are vulnerable to spoofing attacks, which allows for many other forms of attacks on the networks. Although the identity of a node can be verified through cryptographic authentication, authentication is not always possible because it requires key management and additional infrastructural overhead. In this paper we propose a method for both detecting spoofing attacks, as well as locating the positions of adversaries performing the attacks. We first propose an attack detector for wireless spoofing that utilizes K-means cluster analysis. Next, we describe how we integrated our attack detector into a realtime indoor localization system, which is also capable of localizing the positions of the attackers. We then show that the positions of the attackers can be localized using either area-based or point-based localization algorithms with the same relative errors as in the normal case. We have evaluated our methods through experimentation using both an 802.11 (WiFi) network as well as an 802.15.4 (ZigBee) network. Our results show that it is possible to detect wireless spoofing with both a high detection rate and a low false positive rate, thereby providing strong evidence of the effectiveness of the K-means spoofing detector as well as the attack localizer. Secure wireless communications is a challenging problem due to the shared nature of the wireless medium. Most existing security mechanisms focus on traditional cryptographic schemes. In recent years, features of the multi-path channel (such as randomness and reciprocity), have driven researchers to exploit its potential to enhance the security of wireless networks. As OFDM occupies wide bandwidth, it will experience a prolific source of multi-path components. In this paper, we comprehensively exploit the inherent physical parameters of the multi-path fading channel to achieve continuous two way authentication between wireless terminals. In our scheme, pilot information is randomly spread in a wideband channel, leading to low probability of detection (LPD). Unlike other channel-based approaches, the information of both amplitude and phase in the channel signature is fully utilized to enhance the security of the OFDM communication network. More specially, the receiver will detect the channel response continuously according to the randomly inserted pilots and identify the valid user based on the statistical channel signature information. Simulation results indicate the high efficiency of the proposed method. We propose a PHY-authentication protocol to detect spoofing attacks in wireless networks, exploiting the rapid-decorrelation property of radio channels with distance. In this protocol, a PHY-authentication scheme that exploits channel estimations that already exist in most wireless systems, cooperates with any existing---either simple or advanced---higher-layer process, such as IEEE 802.11i. With little additional system overhead, our scheme reduces the workload of the higher-layer process, or provides some degree of spoofing protection for naked" wireless systems, such as some sensor networks. We describe the performance of our approach as a function of the spoofing pattern and the snapshot performance that can be easily measured through field tests. We discuss the implementation issues of the authentication protocol on 802.11 testbeds and verify its performance via field tests in a typical office building. Wireless networks are vulnerable to many identity-based attacks in which a malicious device uses forged MAC addresses to masquerade as a specific client or to create multiple illegitimate identities. For example, several link-layer services in IEEE 802.11 networks have been shown to be vulnerable to such attacks even when 802.11i 1X and other security mechanisms are deployed. In this paper we show that a transmitting device can be robustly identified by its signalprint, a tuple of signal strength values reported by access points acting as sensors. We show that, different from MAC addresses or other packet contents, attackers do not have as much control regarding the signalprints they produce. Moreover, using measurements in a testbed network, we demonstrate that signalprints are strongly correlated with the physical location of clients, with similar values found mostly in close proximity. By tagging suspicious packets with their corresponding signalprints, the network is able to robustly identify each transmitter independently of packet contents, allowing detection of a large class of identity-based attacks with high probability. Physical-layer authentication can address physical layer vulnerabilities and security threats in wireless sensor networks, and has been considered as an effective complementary enhancement to existing upper-layer authentication mechanisms. In this paper, to advance the existing research and improve the authentication performance, we propose a novel physical layer assisted authentication scheme for mobile wireless sensor networks. In our proposed scheme, we explore the reciprocity and spatial uncorrelation of the wireless channel to verify the identities of involved transmitting users and decide whether all data frames are from the same sender. In our proposed scheme, a new method is developed for the legitimate users to compare their received signal strength (RSS) records, which avoids the information from being disclosed to the adversary. Our proposed scheme can detect the spoofing attack even in a high dynamic environment. We evaluate our scheme through experiments under indoor and outdoor environments. Experiment results show that our proposed scheme is more efficient and achieves a higher detection rate as well as keeping a lower false alarm rate. A sybil node impersonates other nodes by broadcasting messages with multiple node identifiers (ID). In contrast to existing solutions which are based on sharing encryption keys, we present a robust and lightweight solution for sybil attack problem based on received signal strength indicator (RSSI) readings of messages. Our solution is robust since it detects all sybil attack cases with 100 completeness and less than a few percent false positives. Our solution is lightweight in the sense that alongside the receiver we need the collaboration of one other node (i.e., only one message communication) for our protocol. We show through experiments that even though RSSI is time-varying and unreliable in general and radio transmission is non-isotropic, using ratio of RSSIs from multiple receivers it is feasible to overcome these problems. We consider a physical layer approach to enhance wireless security by using the unique wireless channel state information (CSI) of a legitimate user to authenticate subsequent transmissions (messages) from this user, thereby denying access to any spoofer whose CSI would significantly differ from that of the legitimate user by virtue of a different spatial location. Past approaches have explicitly utilized underlying CSI estimated from data: is the CSI of the current message the same as that of the previous message? In this paper we formulate this problem as one of comparing two random signal realizations to ascertain whether they have identical power spectral densities. A binary hypothesis testing approach is formulated, analyzed and illustrated via simulations. The wireless medium contains domain-specific information that can be used to complement and enhance traditional security mechanisms. In this paper we propose ways to exploit the fact that, in a typically rich scattering environment, the radio channel response decorrelates quite rapidly in space. Specifically, we describe a physical-layer algorithm that combines channel probing (M complex frequency response samples over a bandwidth W) with hypothesis testing to determine whether current and prior communication attempts are made by the same user (same channel response). In this way, legitimate users can be reliably authenticated and false users can be reliably detected. To evaluate the feasibility of our algorithm, we simulate spatially variable channel responses in real environments using the WiSE ray-tracing tool; and we analyze the ability of a receiver to discriminate between transmitters (users) based on their channel frequency responses in a given office environment. For several rooms in the extremities of the building we considered, we have confirmed the efficacy of our approach under static channel conditions. For example, measuring five frequency response samples over a bandwidth of 100 MHz and using a transmit power of 100 mW, valid users can be verified with 99 confidence while rejecting false users with greater than 95 confidence. We propose an enhanced physical-layer authentication scheme for multi-carrier wireless systems, where transmission bursts consist of multiple frames. More specifically, it is based on the spatial variability characteristic of wireless channels, and able to work with moderate terminal mobility. For the authentication of the first frame in each data burst, the legal transmitter uses the saved channel response from the previous burst as the key for authentication of the first frame in the next burst. The key is obtained either via feedback from the receiver, or using the symmetric channel property of a TDD system. Then the authentication of the following frames in the burst is performed either by a Neyman-Pearson hypothesis test, or a least-squares adaptive channel estimator. Simulations in a typical indoor building show that the scheme based on the Neyman-Pearson test is more robust against terminal mobility, and is able to detect spoofing attacks efficiently with small system overhead when the terminal moves with a typical pedestrian speed. The wireless medium offers many opportunities for broadcast communications. However, it also opens the possibility for attackers to eavesdrop the broadcast data or to pretend to be another node or device. These two attacks define the protection goals, namely, confidentiality and authenticity. Traditionally, both are solved by cryptographic approaches exploiting knowledge available in the surrounding infrastructure. The novel communication paradigms for the Internet of Things or cyber–physical systems do not scale with the standard cryptographic approach. Instead it is possible to exploit properties of the underlying physical channel to provide countermeasures against eavesdropping and impersonation attacks. Thereby, the random fading channel induces uncertainty which is detrimental but at the same time also helpful. In this paper, we review and describe a generalized model for physical-layer-based confidential data transmission and wireless authentication. A key role is played by the channel uncertainty and available design dimensions such as time, frequency, and space. We show that wireless authentication and secret-key generation can work in multicarrier and multiple-antenna systems and explain how even outdated channel state information can help to increase the available secure degrees of freedom. This survey focuses on the system design of wireless physical-layer confidentiality and authenticity under channel uncertainty. The insights could lead to a design of practical systems which are preparing the ground for confidentiality and authenticity already on the physical layer of the communication protocol stack. The broadcast nature of the wireless medium poses a serious challenge to the security of wireless communications and networks. Traditional computational security strategies always fail to prevent the eavesdropper from overhearing the communications. Recently, the unique characteristics of wireless channel fingerprints, e.g. randomness and reciprocity, have been successfully used to enhance the security of the wireless network. We expand our previous work on exploring particular physical parameters of fingerprints, and focus on a new scheme in which we use the RAKE receiver to differentiate users under low transmission power. RAKE receiver may capture and estimate fingerprints through poor autocorrelation of the spreading coding. As the fingerprint is incomputable and unpredictable, and may only be detected by the pair of transmitter and receiver, it may be fully utilized to design an efficient authentication method. Simulation results strongly verify the efficiency of our proposed method, especially in the case of low SNR.