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Mobile multihop relay (MMR) WiMAX networks have attracted lots of interest in the wireless communication industry recently because of its scalable coverage, improved data rates, and relatively low cost. However, security of MMR WiMAX networks is the main challenge to be addressed. In this paper, we first identify several possible attacks on MMR WiMAX networks in which a rogue base station (BS) or relay station (RS) can get authenticated and gain control over the connections and show that the current standard does not address this problem well. We then propose a set of new authentication protocols for protecting MMR WiMAX networks from rogue BS attack, rogue RS attack, and suppress-replay attack. Our protocols can provide centralized authentication by using a trusted authentication server to support mutual authentication between RS and BS, between RS and RS, and between mobile station (MS) and RS. Moreover, our protocols can also provide distributed authentication with a license issued by the trusted server. We use a formal tool called Scyther to analyze and verify the security properties of our protocols. The results show that our protocols can counter rogue BS and RS attacks and suppress-replay attack and are not susceptible to any known attacks. [ABSTRACT FROM AUTHOR]

Flood is a communication primitive that can be used by the base station of a sensor network to send a copy of a message to every sensor in the network. When a sensor receives a flood message, the sensor needs to check whether it has received this message for the first time and so this message is fresh, or it has received the same message earlier and so the message is redundant. In this paper, we discuss a family of four flood sequencing protocols that use sequence numbers to distinguish between fresh and redundant flood messages. These four protocols are: a sequencing free protocol, a linear sequencing protocol, a circular sequencing protocol, and a differentiated sequencing protocol. We analyze the self-stabilization properties of these four flood sequencing protocols. We also compare the performance of these flood sequencing protocols, using simulation, over various settings of sensor networks. We conclude that the differentiated sequencing protocol has better stabilization property and provides better performance than those of the other three protocols. [ABSTRACT FROM AUTHOR]

IPsec is the current security standard for the Internet Protocol IP. According to this standard, a selected computer pair (p, q) in the Internet can be designated a “security association”. This designation guarantees that all sent IP messages whose original source is computer p and whose ultimate destination is computer q cannot be replayed in the future (by an adversary between p and q) and still be received by computer q as fresh messages from p. This guarantee is provided by adding increasing sequence numbers to all IP messages sent from p to q. Thus, p needs to always remember the sequence number of the last sent message, and q needs to always remember the sequence number of the last received message. Unfortunately, when computer p or q is reset these sequence numbers can be forgotten, and this leads to two bad possibilities: unbounded number of fresh messages from p can be discarded by q, and unbounded number of replayed messages can be accepted by q. In this paper, we propose two operations, “SAVE” and “FETCH”, to prevent these possibilities. The SAVE operation can be used to store the last sent sequence number in persistent memory of p once every Kp sent messages, and can be used to store the last received sequence number in persistent memory of q once every Kq received messages. The FETCH operation can be used to fetch the last stored sequence number for a computer when that computer wakes up after a reset. We show that the following three conditions hold when SAVE and FETCH are adopted in both p and q. First, when p is reset, at most 2Kp sequence numbers will be lost but no fresh message sent from p to q will be discarded if no message reorder occurs. Second, when q is reset, the number of discarded fresh messages is bounded by 2Kq. In either case, no replayed message will be accepted by q. [ABSTRACT FROM AUTHOR]

To improve the flow of quality information and combat fake news on social media, it is essential to identify the origins and evolution patterns of false information. However, scholarship dedicated to this area is lacking. Using a recent development in the field of computational network science (i.e., evolution tree analysis), this study examined this issue in the context of the 2016 US presidential election. By retrieving 307,738 tweets about 30 fake and 30 real news stories, we examined the root content, producers of original source, and evolution patterns. The findings revealed that root tweets about fake news were mostly generated by accounts from ordinary users, but they often included a link to non-credible news websites. Additionally, we observed significant differences between real and fake news stories in terms of evolution patterns. In our evolution tree analysis, tweets about real news showed wider breadth and shorter depth than tweets about fake news. The results also indicated that tweets about real news spread widely and quickly, but tweets about fake news underwent a greater number of modifications in content over the spreading process. [ABSTRACT FROM AUTHOR]