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The global coronavirus pandemic is reshaping our daily lives and has forced many people to work and socialize remotely. This trend also increases the demand for highly available and trustworthy Internet access. Compared with 4G networks, 5G mobile networks are designed to accommodate the increasing number of mobile devices with higher transfer speed, lower latency and improved security. The 5G standard in USA uses millimeter waves, which is much shorter than 4G LTE signals. The shorter wavelength means 5G can transfer data much faster than 4G, but it also results in a much shorter travel range. When a user is moving among 5G cells, repeated authentications will increase delay time which contradicts 5G objective. The blockchain technology has the advantage of better transparency, enhanced security and high efficiency. In this paper, we propose an efficient authentication approach for 5G network using blockchain technology to reduce repeated authentications and keep the cost low and practical. We will compare it with some existing protocols and analyze its security against several possible attacks.

An Optical Bust Switching (OBS) network is vulnerable to a range of issues. One of the most significant issues is Burst Header Packet (BHP) flooding attacks, which can negatively impact on the Quality of Service (QoS) and create more urgent issues such as Denial of Service (DoS). Existing techniques for countering BHP flood attacks usually display a low accuracy in detecting misbehaving nodes leading to BHP attacks. By contrast, Machine Learning (ML) is a widely adopted and powerful data analysis technique which has showed a high degree of predictive performance in multiple application domains due to its ability to discover beneficial knowledge for decision-making. This study investigates the use of predictive ML to counter the risk of BHP flooding attacks experienced in OBS networks, proposing a decision tree-based architecture as an appropriate solution. This contains a learning algorithm that extracts novel rules from tree models using data processed from several simulation runs. The results show that the rules derived from our learning algorithm will accurately classify 93% of the BHP flooding attacks into either Behaving (B) or Misbehaving (M) classes. Moreover, the rules can further classify the Misbehaving edge nodes into four sub-class labels with 87% accuracy, including: Misbehaving-Block (Block), Behaving-No Block (No Block), Misbehaving-No Block (M-No Block), and Misbehaving-Wait (M-Wait). The results clearly show that our proposed decision tree model is a viable solution compared to decisions undertaken by expert domains or human network administrators.

Cloud data services have been in rapidly increasing demand by mobile users, but such services often face the problem of lowered QoS due to the lengthy delay of transmitting large amount of data all the way from the cloud server to the mobile client. In this paper, we propose a prefetching-based approach which utilizes the spare bandwidth and storage space of fog networks to prefetch data files from cloud data servers to edge servers in the fog networks that are much closer to the mobile users, thereby providing better data delivery in terms of transmission delay. We propose six possible prefetching schemes which are designed based on different needs of a priori knowledge about the mobile user's file access patterns. Observing that some prefetching scheme performs better than other schemes when facing a particular type of access pattern, our framework also allows the cloud server and edge servers to dynamically switch to another prefetching scheme if the current prefetching scheme does not fit well with the user's access pattern. We use simulations to evaluate the performance of our proposed prefetching schemes, and the results show that each prefetching scheme can reduce transmission delay, and that the dynamic scheme switching can help improve the performance in terms of prefetching precision and recall ratios.

Web-based advertising system has become a convenient and efficient channel for advertisers to deliver ads to targeted Internet users. Unfortunately, this system has been exploited by cybercriminals to disseminate malware to an enormous number of end-users and their vulnerable machines. To protect their malicious ads and malware from detection by the ad network, malvertisers apply a variety of evasion techniques such as fingerprinting the execution environment, redirecting to compromised IP addresses, and malware polymorphism. On the other hand, the ad network can also apply inspection techniques to spoil the malvertiser's tricks and expose the malware. However, both the malvertiser and the ad network are under the constraints of resource and time. In this paper, we aim to apply game theory to formulate the problem of inspecting the malware inserted by the malvertisers into the Web-based advertising system. We design a normal form game between the malvertiser and the ad network, define their strategies and payoff functions, and compute their pure-strategy and mixed-strategy Nash equilibria. We use numeric simulation to evaluate our game theoretic models, and derive several insights from the results that can serve as guidelines for the ad network to decide its best inspection strategy.1

The development of wireless Vehicular Ad-Hoc Network (VANET) aimed to enhance road's safety and provide comfortable driving environment by delivering early warning and infotainment messages. Intentional jamming attacks target at undermining such a goal by disrupting wireless communications. While detecting jamming attacks is important towards enhancing road safety, it is challenging because VANET operates in outdoor environment (highly changeable road conditions and atmospheric phenomena), and encompasses volatile topology and high mobility of vehicles (traveling speed and directions). To overcome these challenges, in this work, we study jamming attack mobility and behaviors in IEEE802.11p networks. In particular, we focus on analyzing jamming impact based on jammers behaviors, and mobility patterns. Thus, in order to achieve reliable detection, first we identify the impact of vehicles' density on network performance. Then, we study jamming effectiveness when adopting different mobility patterns (stationary, random, or targeting) and behaviors (constant, random, and reactive). Finally, we propose a two phase detection algorithm and evaluate it in a simulation environment. Our approach shows promising results to detect different types of jammers accurately in IEEE802.11p networks.

HTTP is becoming the most preferred channel for command and control (C&C) communication of botnets. One of the main reasons is that it is very easy to hide the C&C traffic in the massive amount of browser generated Web traffic. However, detecting these HTTP-based C&C packets which constitute only a minuscule portion of the overall everyday HTTP traffic is a formidable task. In this paper, we present an anomaly detection based approach to detect HTTP-based C&C traffic using statistical features based on client generated HTTP request packets and DNS server generated response packets. We use three different unsupervised anomaly detection techniques to isolate suspicious communications that have a high probability of being part of a botnet's C&C communication. Results indicate that our method can achieve more than 90% detection rate while maintaining a reasonably low false positive rate.

Routing is one of the most challenging development issues in Delay-Tolerant Networks (DTNs) because of lack of continuous connection. Existing routing schemes for DTNs provide best effort service, but are unable to optimize QoS and support message priority. In this paper, we present a Look-Ahead Routing and Message Scheduling approach (ALARMS) which exploits more accurate knowledge about various parameters regarding routing to achieve better QoS in the DTN. We assume a variation of the well-known ferry model, in which there are ferry nodes moving along pre-defined routes to exchange messages with the gateway node of each region on the route and also pass to the gateway nodes look-ahead routing information about when it will arrive at each gateway node on the route in the next two rounds and how long it will stay. The gateway nodes use this information to estimate the delivery delay of each message when being delivered by different ferries, and schedule the message to be delivered by the ferry which arrives earliest at the destination. Simulation results show that ALARMS outperforms three existing routing protocols: epidemic routing, Spray-and-Wait, and Spray-and-Focus, in terms of delay time, delivery ratio, and overhead. We also discuss five enhancement strategies on ALARMS and how ALARMS can support message prioritization.

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.

WiMAX technology, the commercialization of the evolving IEEE 802.16 standard, aims to solve the last-mile problem with broadband wireless access at the scale of metropolitan area networks. WiMAX has attracted significant attention and interest because of its wide transmission range, high transmission rate, and mobility support. However, to make WiMAX networks usable and reliable, several security issues must be addressed in the standard and its protocols. In this article, the authors give an introduction to the security protocols used in WiMAX networks and then discuss why these protocols are deficient in terms of anti-replay, efficiency, scalability, and forward and backward secrecy, as well as how they can be enhanced to address these issues for real applications.

Optical burst switching (OBS) network is a promising switching technology for building the next-generation of Internet backbone infrastructure. It works by assembling UDP packets and sending a burst header packet (BHP) in order to reserve the required network resources along the path before sending the corresponding data burst. If a source node (ingress) gets compromised by an attacker and floods the network with only BHPs to reserve resources without sending actual data, a denial of service attack can occur. In this paper, we propose and develop a new security model that can be embedded into an OBS core switch architecture to prevent BHP flooding attacks. The countermeasure security model allows the OBS core switch to classify the ingress nodes based on their behavior and the amount of reserved resources that are not being utilized. A malicious node that causes BHP flooding attack will be blocked by the developed model until the risk disappears. The security model is implemented, tested and verified using a modified NCTUns network simulator. The analysis conducted reveals that our proposed model is effective in countering BHP flooding attacks as well as in providing the network resources to the legitimate nodes.

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.

Effectively adding security measures to a multicast service is an intriguing problem, especially when the service isdeployed in a wireless setting. Next generation IEEE 802.16standard WirelessMAN networks are a perfect example of this problem, and the latest draft specification of the standard includes a secure protocol solution called Multicast and Broadcast Rekeying Algorithm (MBRA). In this paper, we expose the security problems of MBRA, including non-scalability and omission of backward and forward secrecy, and propose new approaches, ELAPSE and ELAPSE+, to address these problems. In particular, ELAPSE+ makes use of membership and mobility information gathered in the application layer to augment the adaptive group management in the MAC layer. We analyze the security property of ELAPSE and ELAPSE+, and compare their performances with MBRA by simulating group rekeying scenarios.

We propose an architecture for securely resolving IP addresses into hardware addresses over an Ethernet. The proposed architecture consists of a secure server connected to the Ethernet and two protocols: an invite-accept protocol and a request-reply protocol. Each computer connected to the Ethernet can use the invite-accept protocol to periodically record its IP address and its hardware address in the database of the secure server. Each computer can later use the request-reply protocol, to obtain the hardware address of any other computer connected to the Ethernet from the database of the secure server. These two protocols are designed to overcome the actions of any adversary that can lose sent messages, arbitrarily modify the fields of sent messages, and replay old messages.

Location tracking applications are usually based on exact GPS location information and non-anonymized WiFi Access Point (AP) information. It has been assumed that anonymizing WiFi AP information is an effective way to preserve location privacy of the connected users. In this work, our goal is to show that the privacy of connected users' movement pattern can still be compromised by a determined attacker even if the WiFi AP information is anonymized. We investigated the feasibility of tracking user's movement between locations from anonymized WiFi AP BSSIDs based on large Device Analyzer datasets. Our experiments show that the user's daily movement pattern can be identified with almost 83% accuracy.

Our goal in this chapter is to introduce a router-based filtering technology aimed at enhancing the availability and performance of cloud computing. When this technology is integrated with cloud auditing methods, it can make use of cloud auditing information to detect malicious intrusion and traffic anomalies, and to define appropriate filtering rules that can be exchanged between routers in the network, for filtering malicious traffic early and rerouting excessive legitimate requests to other suitable replicated servers. We first give an overview of the specification and generation of filtering rules used by routers. Then we present a theoretical model to find the best locations for hardware routers in a network to block malicious traffic, and discuss how to integrate this theoretical model with cloud auditing techniques. Finally, we present results of experiments that validate our router-based filtering approach.

While many security schemes protect the content of messages in the Distributed Sensing Systems (DSS), the contextual information, such as communication patterns, is left vulnerable and can be utilized by attackers to identify critical information such as the locations of event sources and message sinks. Existing solutions for location anonymity are mostly designed to protect source or sink location anonymity individually against limited eavesdroppers on a small region at a time. However, they can be easily defeated by highly motivated global eavesdroppers that can monitor entire communication events on the DSS. To grapple with these challenges, we propose a mechanism for Preserving Anonymity of Sources and Sinks against Global Eavesdroppers (PASSAGES). PASSAGES uses a small number of stealthy permeability tunnels such as wormholes and message ferries to scatter and hide the communication patterns. Unlike prior schemes, PASSAGES effectively achieves a high anonymity level for both source and sink locations, without incurring extra communication overheads. We quantify the location anonymity level and evaluate the effectiveness of PASSAGES via analysis as well as extensive simulations. We also perform evaluations on the synergistic effect when PASSAGES is combined with other traditional solutions.

3GPP-LTE networks use the EAP-AKA protocol to authenticate and negotiate session keys with mobile users. However, with the popular trend of single user owning multiple devices and subscribing to multiple services, the EAP-AKA protocol appears inefficient because its authentication is device-oriented. In this paper, we propose a secure and efficient multi-device and multi-service authentication protocol, called SEMMAP, for 3GPP-LTE networks. SEMMAP makes use of a key hierarchy and an authority-issued license to enable an authenticating server to quickly verify the legitimacy of multiple devices belonging to the same mobile user and conduct a fast key negotiation between the server and the mobile user. Performance analysis shows that SEMMAP is more efficient than the current EAP-AKA protocol under the multi-device, multi-service scenario in terms of authentication delay and storage overhead for Authentication Vector (AV) at authenticating servers.

Recently Vehicular Ad-Hoc Network (VANET) is becoming popular because of its promise for improving driving experience with respect to both safety and convenience concerns. One of the most important applications is to disseminate emergency notification messages to drivers in order to notify them the occurrence of an accident. The core challenge of message dissemination schemes in VANET is how to select the next forwarding node to further forward the message. In this paper, we proposed a Traffic-Aware Geographic forwarding (TAG) protocol for VANET message dissemination. The proposed TAG protocol takes both the real map information and traffic flow information into account to identify the vehicles that are "relevant" to the broadcast packet in question, and selects forwarding nodes accordingly aiming to optimize efficiency and minimize the number of unnecessary transmission. We evaluate the performance of our TAG protocol and compare it with three variations through simulations, and the results show that the TAG forwarding protocol can efficiently forward the message with the lowest number of transmission, the lowest involved vehicles ratio without sacrificing much on coverage.

In today's distributed service system which is often composed of heterogeneous servers and clients, the assurance of continuous operation of such system relies heavily on two things: the server continues to faithfully fulfill its duties, and the client continues to faithfully fulfill its obligations. However, as the complexity of distributed service system grows, it becomes much harder to correctly identify who is accountable for a service interruption or discontinuation when it occurs. In this paper, we propose an object-oriented approach to model and automate the analysis of server duty and client obligation for achieving high assurance of continuous service. With the formal model of server duty-client obligation interaction string and the use of an Accountability Analysis Engine, the proposed approach can effectively identify the party at fault in either online or offline mode when service interruption or discontinuation occurs.

Botnets have become the top threat to Internet security. Botnets generate and transmit huge amounts of malicious traffic for various purposes. In this paper, we propose a dynamic programming based algorithm to calculate a set of appropriate routers for placing early filters of malicious traffic in the network in order to maximize the benefits of early malicious traffic filtering. Moreover, we discuss how to combine our early filtering approach and the QoS routing of traffic so that the bandwidth saved by early filtering of malicious traffic can be efficiently utilized by legitimate traffic.

Mobile multi-hop 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. In this paper, we first identify a possible attack on MMR WiMAX networks in which a rogue base station (BS) or relay station (RS) can get authenticated and gain control over the connections. We also 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 and rogue RS attacks. Our protocols provide centralized authentication by using a trusted authentication server to support mutual authentication between RS and BS, between RS and RS, and between MS and RS. Our protocols can also provide distributed authentication with a license issued by the trusted server.

IEEE 802.16 based broadband wireless access network is considered as one of the most promising wireless access technologies. It employs a request/grant scheme in bandwidth allocation where each subscriber station (SS) can send bandwidth requests (BRs) to the base station (BS) before bandwidth can be granted to SSs. The 802.16 standard defines two types of BR strategies, namely incremental requests and aggregate requests. In this paper, we first present an analytic model to analyze their performance and show that both types of BRs have rooms for improvement when facing two common types of traffic patterns, called the uphill traffic pattern and the periodic/bursty traffic pattern, in terms of overhead and data waiting time in the queue. Then, we propose two enhancement strategies, called the aggressive strategy and the conservative strategy, that exploit the property of the two traffic patterns to improve the performance. The simulation results show that the two enhancement strategies can effectively reduce the overhead and data waiting time, at the price of somewhat less bandwidth utilization in the case of conservative strategy.

Sequence numbers have been used by a variety of network protocols as freshness identifiers to achieve reliable transmission and provide protection against replay attacks. The number of bits allocated for a sequence number shall not be too small in order to avoid frequent wraparounds and replay attacks. However, in a sensor network consisting of resource-constrained sensor nodes, transmitting a full sequence number along with a message represents considerable overhead that is desirable to be avoided. In this paper, we propose LOFT, a protocol that lowers the overhead of transmitting freshness identifiers along with messages. In LOFT, the sender and receiver still maintain a sequence number of the same number of bits, but when the sender sends a new message, it only transmits a less significant portion of the sequence number bits in order to save energy. All the bits of the sequence number are involved in the computation of a message authentication code, so that the receiver can verify the freshness of the message. Moreover, LOFT makes use of Bloom filter to mitigate the overhead of freshness check caused by DoS attacks. We use simulations to analyze how much a portion of the sequence number should be transmitted to achieve best performance in terms of efficiency and effectiveness.

Multicast enables efficient large-scale content distribution and has become more and more popular in network service. Security is a critical issue for multicast because many applications require access control and privacy. This issue is more sensitive to wireless network, which is lack of physical boundaries. IEEE 802.16 is the standard for next generation wireless network, which aims to provide the last mile access for Wireless Metropolitan Area Network (WirelessMAN). Multicast is also supported in IEEE 802.16, and a Multicast and Broadcast Rekeying Algorithm (MBRA) was proposed in the standard as an optional function for secure multicast. However, this algorithm does not provide backward and forward secrecy. It is not scalable to a large group either. This paper reviews the above two deficiencies of MBRA and proposes revision to address these problems for Intra-BS multicast. We also propose algorithms for secure multicast in different scenarios of WirelessMAN besides its basic schema, including Inter-BS multicast, multicast for mesh network, and multicast during handover.

IEEE 802.16 is the standard for broadband wireless access. The security sublayer is provided within IEEE 802.16 MAC layer for privacy and access control, in which the Privacy and Key Management (PKM) protocols are specified. This paper models the PKM protocols using Casper and analyzes the CSP output with FDR, which are formal analysis tools based on the model checker. Later versions of PKM protocols are also modeled and analyzed. Attacks are found in each version and the results are discussed.

Static replicas have been proven useful in providing fault tolerance and load balancing, but they may not provide enough assurance on the continuous availability of mission- critical data in face of a determined denial-of-service (DoS) attacker. A roaming replica scheme can provide higher availability assurance, but the overhead associated with replica movement and lookup is high. In this paper, we propose ARRP, an adaptive roaming replication protocol in which static replicas are used normally but if a certain percentage of static replicas has already been shut down, then a small number of roaming replicas will be added and stored in randomly selected hosts that are changed periodically. In particular, we analyze the appropriate threshold when the roaming replica scheme should be enabled by empirically investigating the tradeoff between availability, performance, and overhead. Simulation results show that ARRP can effectively mitigate the impacts of DoS attacks and host failures to ensure continuous availability of critical data, with better performance and reasonable overhead compared to only using static replicas.

Voice over Internet Protocol (VoIP) service has been a very popular and important application over the Internet. Wireless VoIP also becomes more and more popular due to its features of low cost and convenience. Recently, wireless mesh network has been considered as a good solution for VoIP services since it is easy to deploy and provides a larger area coverage. However, the security and performance are the main challenges. In this work, we focus on the security issues and present a new protocol for securing the voice traffic over the wireless mesh network, including the client authentication, intermediate mesh nodes authentication to ensure secure multi-hop communication, voice traffic confidentiality and secure optimal routing selection by using the probing packets.

The next generation broadband wireless networks support real-time applications like VOIP and video streaming. They allow users to roam over the network seamlessly and securely. Current design incurs lengthy delay between breaking of previous connection and making of next connection. Cross layer design and cross function optimization are required to improve the handover latency of broadband wireless networks. We discuss the fast handover algorithms that combine the mechanisms in the MAC layer with that of the IP layer. Fast key exchange and fast authentication procedures are introduced to reduce authentication time during network re-entry. The effects of latency reduction by fast authentication are compared with results of other solutions. We also discuss standard activity for media independent handover in heterogeneous networks.

In this paper, we present two new centralized group key management protocols based on the Chinese Remainder Theorem (CRT). By shifting more computing load onto the key server we optimize the number of re-key broadcast messages, user-side key computation, and number of key storages. The first protocol is the base Chinese Remaindering Group Key (CRGK) protocol, which with a group of n users requires the key server to do O(n) XORs, additions, multiplications, and Extended Euclidean Algorithm computations and broadcast 1 re-key message; each individual user is required to do only 1 modulo arithmetic and 1 XOR operation for each group key update. The second protocol is the Fast Chinese Remaindering Group Key (FCRGK) protocol, which only requires the key server to do O(n) XORs, additions, and multiplications most of the times with no change to the number of re-key messages and user computation per group key update. For both protocols each user only needs to store 2 keys all the time. One special attraction for our FCRGK protocol is that it allows most of the re-keying computation to be done preemptively, which means when a user-join or user-leave event happens the response time for the key server to send out the new group key can be very short.

Multicast enables efficient large-scale content distribution and has become more and more popular in network service. Security is a critical issue for multicast because many applications require access control and privacy. This issue is more sensitive to wireless network, which is lack of physical boundaries. IEEE 802.16 is the standard for next generation wireless network, which aims to provide the last mile access for wireless metropolitan area network (WirelessMAN). Multicast is also supported in IEEE 802.16, and a multicast and broadcast rekeying algorithm (MBRA) is proposed as an optional function for secure multicast. However, this algorithm does not provide backward and forward secrecy, and is not scalable to large group. This paper reviews the above two deficiencies of MBRA and proposes a new algorithm to address them. We also propose algorithms for secure multicast in different scenarios of WirelessMAN besides its basic scheme.

Multicast delivery of data is a powerful mechanism that has strong potential in next generation networks. The increased efficiency over unicast is a definite advantage, but the use of multicast poses many security risks. Effectively adding security measures to a multicast service is an intriguing problem, especially when the service is deployed in a wireless setting. Next generation IEEE 802.16 standard WirelessMAN networks are a perfect example of this problem, and the latest draft specification of the standard includes a secure protocol solution called multicast and broadcast rekeying algorithm (MBRA). In this paper, we expose the security problems of MBRA, including non-scalability and omission of backward and forward secrecy, and propose a new approach, ELAPSE, to address these problems. We analyze the security property of ELAPSE and use Qualnet simulations to show its efficiency

Cookies are the primary means for Web applications to authenticate HTTP requests and to maintain client states. Many Web applications (such as electronic commerce) demand a secure cookie protocol. Such a protocol needs to provide the following four services: authentication, confidentiality, integrity and antireplay. Several secure cookie protocols have been proposed in previous literature; however, none of them are completely satisfactory. In this paper, we propose a secure cookie protocol that is effective, efficient, and easy to deploy. In terms of effectiveness, our protocol provides all of the above four security services. In terms of efficiency, our protocol does not involve any database lookup or public key cryptography. In terms of deployability, our protocol can be easily deployed on an existing Web server, and it does not require any change to the Internet cookie specification. We implemented our secure cookie protocol using PHP, and the experimental results show that our protocol is very efficient.

Without physical boundaries, a wireless network faces many more vulnerabilities than a wired network does. IEEE 802.16 provides a security sublayer in the MAC layer to address the privacy issues across the fixed BWA (broadband wireless access). Several articles have been published to address the flaws in IEEE 802.16 security after IEEE 802.16-2001 was released. However, even the enhanced version IEEE 802.16-2004 does not settle all the problems and additional flaws emerge. In addition, we found that PKM (privacy and key management) protocols version 2 (PKMv2), proposed by recently released IEEE 802.16e, is also vulnerable to new attacks. In this paper, we first overview the IEEE 802.16 standard, especially the security sublayer, and then investigate possible attacks on the basic PKM protocol in IEEE 802.16 as well as in its other versions from related works and the newest PKMv2. We also give possible solutions to counter those attacks and verify our analysis using formal (BAN) logic.

Real time network monitoring for intrusions is offered by various host and network based intrusion detection systems. These systems largely use signature or pattern matching techniques at the core and thus are ineffective in detecting unknown anomalous activities. In this paper, we apply signal processing techniques in intrusion detection systems, and develop and implement a framework, called Waveman, for real time wavelet-based analysis of network traffic anomalies. Then, we use two metrics, namely percentage deviation and entropy, to evaluate the performance of various wavelet functions on detecting different types of anomalies like Denial of Service (DoS) attacks and portscans. Our evaluation results show that Coiflet and Paul wavelets perform better than other wavelets in detecting most anomalies considered in this work.

Capturing an E-mail worm and containing its propagation as early as possible is desirable in order to provide better protection for the networks and hosts against severe damage that may be caused by the worm. In this paper, we propose a new approach that makes use of the propagating nature of E-mail worms. This approach inserts into each client's address book a dummy E-mail address that is not used by any registered user of the local domain, such that we can be confident that any E-mail destined to this dummy E-mail address is generated by an E-mail worm. The captured signatures can then be used to construct a user blacklist and a signature blacklist to contain the propagation of this E-mail worm. We also discuss how E-mail worms can attempt to bypass the dummy E-mail address, and propose countermeasures against these attempts. Our prototype implementation shows that this approach is easily deployable and is effective in containing E-mail worms.

Without physical boundaries, a wireless network faces many more security threats than a wired network does. Therefore, in the IEEE 802.16 standard a security sublayer is specified in the MAC layer to address the privacy issues across the fixed Broadband Wireless Access (BWA). Several articles have been published to address the flaws in IEEE 802.16 security after the IEEE standard 802.16-2001 was released. However, the IEEE standard 802.16-2004 revision does not settle all the discovered problems and additional flaws remain. This paper gives an overview of the IEEE 802.16 standard, focusing on the MAC layer and especially the security sublayer. We analyze the security flaws in the standard as well as in related works, and illustrate possible attacks to the authentication and key management protocols. Possible solutions are also proposed to prevent these attacks. Finally, we propose a security handover protocol that should be supported in the future 802.16e for mobility.

Most wireless ad hoc sensor networks are susceptible to routing level attacks, in which an adversary masquerades as a legitimate node to convince neighboring nodes that it is the "logical" next hop or is on a "better" path for forwarding packets, and arbitrarily drops the packets forwarded by neighboring nodes. In this paper, we propose a secure unicast messaging protocol (SUMP) for wireless ad hoc sensor networks to mitigate the threat of routing level attacks. SUMP groups nodes into levels based on hop count to provide hop-by-hop group authentication using Merkel hash trees. This method allows for varied levels of security in accordance with a node's hop count from the base station and secure, directed unicast communications from the base station to individual nodes. Unlike other sensor network security protocols that require the storage of parent node information, a sensor node running SUMP does not store parent node information, therefore preventing an adversary from gaining information of other nodes from a compromised node.

In this paper, we first identify a vulnerability of IEEE 802.11 wireless LANs in which a compromised access point can still authenticate itself to a wireless station and gain control over the connection, and show that the current IEEE 802.11i standard does not address this problem. We then propose a new protocol that can counter this attack by providing dual authentication for both a wireless station and its corresponding access point at connection setup time using the authentication server. We also consider roaming situations and present a roaming authentication protocol. Finally, we show that our protocol is in conformance with the requirements of the IEEE 802.11i standard, and show that it performs no worse with respect to communication time than IEEE 802.11i using a prototype implementation of each protocol

IPsec is the current security standard for the Internet Protocol IP. According to IPsec, 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 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 qf 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 member in persistent memory of p once every K/sub p/ sent messages, and can be used to store the last received sequence number in persistent memory of q once every K/sub q/ received messages. The FETCH operation can be used to fetch the last stored sequence number for a computer when that computer wakes tip 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 2K/sub p/ 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 2K/sub q/, In either case, no replayed message will be accepted by q.

A key tree is a distributed data structure of security keys that can be used by a group of users. In this paper we describe how any user in the group can use the different keys in the key tree to securely multicast data to different subgroups within the group. The cost of securely multicasting data to a subgroup whose users are "consecutive" is O(log n) encryptions, where n is the total number of users in the group. The cost of securely multicasting data to an arbitrary subgroup is O(n/2) encryptions. However this cost can be reduced to one encryption by introducing an additional key tree to the group.

The anti-replay window protocol is used to secure IP against an adversary that can insert (possibly replayed) messages in the message stream from a source computer to a destination computer in the Internet. We discuss this important protocol and point out a potential problem faced by the protocol, in which severe reordering of messages can cause the protocol to discard a lot of good messages. We then introduce a controlled shift mechanism that can reduce the number of discarded good messages by sacrificing a relatively small number of messages. We use simulation to show that the modified protocol is more effective than the original protocol when a severe reordering of messages occurs. In particular, we show that the modified protocol reduces the number of discarded good messages by up to 70%.

A computer network is said to provide hop integrity iff when any router p in the network receives a message m supposedly from an adjacent router q, then p can check that m was indeed sent by q, was not modified after it was sent, and was not a replay of an old message sent from q to p. In this paper, we describe three protocols that can be added to the routers in a computer network so that the network can provide hop integrity, and thus overcome most denial-of-service attacks. These three protocols are a secret exchange protocol, a weak integrity protocol, and a strong integrity protocol. All three protocols are stateless, require small overhead, and do not constrain the network protocol in the routers in any way.

The anti-replay window protocol is used to secure IP against an adversary that can insert (possibly replayed) messages in the message stream from a source computer to a destination computer in the Internet. In this paper, we verify the correctness of this important protocol using standard methods (i.e. auxiliary variables, annotation, and invariants). We show that despite the adversary, the protocol delivers each message at most once, and discards a message only if another copy of this message has already been delivered, or the message has suffered a reorder of degree w or more, where w is the window size. We then develop another variation of this protocol that uses two windows of size w/2 each. This protocol delivers every message at most once, and discards a message only if another copy of this message has already been delivered, or the message has suffered a reorder of degree w+d or more, where d is the sum of current distances between successive windows in the protocol. We argue that the double-window protocol is more effective than the original single-window protocol.

We present a formal specification of the PING protocol, and use three concepts of convergence theory, namely closure, convergence, and protection, to show that this protocol is secure against weak adversaries (and insecure against strong ones). We then argue that despite the security of PING against weak adversaries, the natural vulnerability of this protocol (or of any other protocol for that matter) can be exploited by a weak adversary to launch a denial of service attack against any computer that hosts the protocol. Finally, we discuss three mechanisms, namely ingress filtering, hop integrity, and soft firewalls that can be used to prevent denial of service attacks in the Internet.

Most wireless ad hoc sensor networks are susceptible to routing level attacks, in which an adversary masquerades as a legitimate node to convince neighbouring nodes that it is the 'logical' next hop or is on a 'better' path for forwarding packets and arbitrarily drops the packets forwarded by neighbouring nodes. In this paper, we propose a Secure Unicast Messaging Protocol (SUMP) for wireless ad hoc sensor networks to mitigate the threat of routing level attacks. SUMP groups nodes into levels based on hop count to provide hop-by-hop group authentication using Merkle hash trees. This method allows for varied levels of security in accordance with a node's hop count from the base station and secure, directed unicast communications from the base station to individual nodes. Unlike other such protocols the parent information maintained by a node running SUMP is securely provided by the base station and thus mitigates the threat of the adversary convincing a node to forward through a non-existent path.