Backdoor attacks on reinforcement learning implant a backdoor in a victim's policy. Once the victim observes trigger signals, it switches to the abnormal mode and fails its task. Most existing attacks assume the adversary can arbitrarily modify the victim's observations (i.e., vision-perturbation), which may be impractical. A more practical way is letting one adversary agent use its actions to affect the victim's observations (i.e., action-perturbation). However, in partially observable multiagent systems, agents may not always be able to observe others. When and how much the adversary agent can affect others' observations are uncertain. Also, we want the adversary agent to trigger others' backdoors with a few actions for stealthiness. To achieve that, we first design a novel training framework to produce auxiliary rewards that measure the influence of each trigger action on others' observations. We then use these rewards to train a trigger policy that guides the adversary agent to efficiently affect others' observations. Given the affected observations, we train the other agents to perform abnormally. Experiments show that the proposed method enables the adversary agent to trigger others' backdoors efficiently. Finally, we study the defense methods against the attack and provide insights for the deployment of multiagent systems.

Location-based service (LBS) applications have become increasingly popular in the past few years. These applications request users' mobile devices to provide location data in terms of a mobile user's position, movement direction, and speed. The proximity testing, as a core application of Location-based services in social networking, enables a user to know whether people are within a given geometric range. However, private location data may be leaked due to the lack of corresponding privacy protection mechanism, which could result in serious security issues. To protect users' confidential location data, a privacy-preserving proximity testing (PPPT) using location grids is designed to improve the efficiency while protecting users' location privacy. The proposed scheme can test whether a person is within a given search area without the disclosure of any private location information. The security analysis and the performance evaluation results show that the proposed PPPT scheme is not only privacy-preserving, but also more efficient.

The Internet Protocol version 6 (IPv6) over low power wireless personal area networks (6LoWPANs) has introduced IP technologies to wireless sensor networks, which significantly promotes the development of the Internet of Things. To support effective mobility management of these resource constrained IP-based sensor nodes, the Proxy Mobile IPv6 has been proposed as a standard to minimize the communication over-head of those nodes. Although the standard has specified some issues of security and mobility in 6LoWPANs, the issues of supporting secure group handovers have not been addressed much by the currently existing solutions. To further reduce the handover latency and signaling overhead, a fast group authentication scheme is proposed in this paper to support secure and seamless handovers for multiple resource constrained 6LoWPAN devices. With the consideration of mobile sensors with limited energy, only simple hash functions and symmetric encryption algorithms are used. The security analysis and the performance evaluation show that the proposed 6LoWPAN group handover scheme could enhance the security functionalities with high efficiency to achieve a fast authentication for handovers.

The Internet Protocol version 6 (IPv6) over Low Power Wireless Personal Area Networks (6LoWPAN), which is a promising technology to promote the development of the Internet of Things (IoT), has been proposed to connect millions of IP-based sensing devices over the open Internet. To support the mobility of these resource constrained sensing nodes, the Proxy Mobile IPv6 (PMIPv6) has been proposed as the standard. Although the standard has specified some issues of security and mobility in 6LoWPANs, the issues of supporting secure group handovers have not been addressed much by the current existing solutions. In this paper, to reduce the handover latency and signaling cost, an efficient and secure group mobility scheme is designed to support seamless handovers for a group of resource constrained 6LoWPAN devices. With the consideration of the devices holding limited energy capacities, only simple hash and symmetric encryption method is used. The security analysis and the performance evaluation results show that the proposed 6LoWPAN group handover scheme could not only enhance the security functionalities but also support fast authentication for handovers.

A seamless and secure handover is always one of the important design goals of the cellular networks . The handover scheme of 4G Long Term Evolution (LTE) wireless networks is complex due to the presence of two possible different types of base stations . In LTE communication systems , a normal base station is referred to as an eNodeB (eNB). What increases the level of complexity of the system is the fact that the other kind of base stations, namely, Home eNodeB (HeNB), cannot directly communicate with eNB. In the LTE networks , the handover scenarios involving a HeNB could result in a complicated handover procedure . Besides, since key chains have been used in the handover processes , it is found to be lack of backward security. Therefore, in order to handle the handover involving a HeNB efficiently with security provisioning, in this paper, a proxy signature-based handover scheme is proposed. The proposed scheme works based on the Elliptic Curve Cryptography (ECC) algorithm, which makes the computational cost of the handover process smaller compared to other handover schemes.

In order to promote the development of the IoT, the Internet Engineering Task Force (IETF) has been developing a standard named Internet Protocol Version 6 (IPv6) over Low Power Wireless Personal Area Networks (6LoWPAN) to enable IP-based devices to connect to the Internet. Besides, to support mobility management, a network-based localized mobility management (NETLMM) protocol named Proxy Mobile IPv6 (PMIPv6) is proposed. Although the 6LoWPAN standard has specified the important issues, some security and mobility issues have not been addressed. In this paper, a secure PMIPv6-based mobility scheme is designed. The proposed scheme enables a 6LoWPAN device to efficiently and securely roam in the 6LoWPAN networks. The formal verification by the Automated Validation of Internet Security Protocols and Applications (AVISPA) and the simulation by JAVA show that the proposed scheme in 6LoWPAN could efficiently enhance the security functionalities to prevent various malicious attacks with less computational cost.

The machine-to-machine (M2M) communication, which plays a vital role in the Internet of Things (IoT), allows wireless and wired systems to monitor environments and exchange the information among various machines automatically without human interventions. In order to promote the development of the IoT and exploit the M2M applications, the Internet Engineering Task Force (IETF) has been developing a standard named Internet Protocol version 6 (IPv6) over low-power wireless personal area networks (6LoWPAN) to enable IP-based M2M devices to connect to the open Internet. Although the 6LoWPAN standard has specified the important issues in the M2M communications, various security issues have not been addressed. In this paper, an enhanced mutual authentication and key establishment scheme is designed for the M2M communications in 6LoWPAN networks. The proposed scheme enables a 6LoWPAN device to securely authenticate with the remote server with a session key established between them. The security proof by the protocol composition logic can prove the logic correctness of the proposed scheme. The formal verification and the simulation show that the proposed scheme in 6LoWPAN could not only enhance the security functionality with the ability to prevent various malicious attacks, but also incur less computational and transmission overhead.