Systems exploiting network coding to increase their throughput suffer greatly from pollution attacks, which consist of injecting malicious packets in the network. The pollution attacks are amplified by the network coding process, resulting in a greater damage than under traditional routing. In this paper, we address this issue by designing an unconditionally secure authentication code (that is, which does not rely on computational assumptions) suitable for multicast network coding, where the keying material is initially computed and distributed by a trusted authority to the destinations and intermediate nodes. The proposed scheme allows not only destinations, but also intermediate nodes, to verify the integrity and origin of the packets received without having to decode, and thus detect and discard the malicious messages in transit that fail the verification. This way, the pollution is canceled out before reaching the destinations. The proposed scheme is robust against pollution attacks from outsiders, as well as coalitions of malicious insider nodes, which have the ability to perform the integrity check, but instead get corrupted and use their knowledge to themselves attack the network. We analyze the performance of the scheme in terms of both throughput and goodput and show that the price to pay for tolerating inside attackers is a high decrease in throughput (it is inversely proportional to the number of insider attackers that can collude). We finally discuss applications to file distribution.

Anonymity and specifically sender anonymity have become essential requirements for many privacy-related applications (e.g. net counselling and whistle blowing). On the other hand, anonymity may be abused for various malicious activities (e.g. redistribution of copy-righted contents and illegal drug trading). In this paper, we address both by proposing protocols for authenticated anonymous communications channels. In such channels, the client can authenticate the authentication server while the latter can only authenticate the fact that the client is one of the qualified members that are eligible to use the network (e.g. WLAN hot spots, WiMAX). Our protocols are based on an efficient anonymous password-based authenticated key exchange protocol and on an anonymous IP address assignment and have the following advantages: (1) they can restrict the usage of the established anonymous channels to certain fair purposes; (2) they do not involve rerouting of the packets through a chain of intermediate nodes; (3) they are available right after registration of a normal password to an authentication server as for a classical non-anonymous authentication (e.g. EAP-TTLS and PEAP) and do not require any special registration procedures that would reveal initially to the authentication server that the client belongs to a small list of users of anonymous services. Each protocol fits in a different authentication framework (IEEE802.1x and PANA) and is different with respect to providing controlled IP address assignment.

The concept of personal networks is very user- centric and representative for the next generation networks. However, the present security mechanism is not considering at all what happens whenever a mobile node (device) is compromised, lost or stolen. This kinds of leakage of stored secrets has been a great danger in the field of communication security since it sometimes leads to the complete breakdown of the intended security level. In order to solve the problem, we propose a 3-way leakage-resilient and forward-secure authenticated key exchange (3LRFS-AKE) protocol and its security architecture for personal networks. The 3LRFS-AKE protocol guarantees not only forward secrecy of the shared key between device and its server but also a new additional layer of security against leakage of stored secrets. The security architecture includes two different types of communications: PN wide communication and communication between P-PANs of two different users.

A private-personal area network (P-PAN) is the very user-centric and basis component of personal networks. However, the current security mechanism is not robust against leakage of stored secrets that can happen when a mobile node (device) is compromised, lost or stolen. This results in unauthorized accesses to other devices and services. For that, this paper introduces a leakage-resilient and forward secure authenticated key exchange (LRFS-AKE) protocol and its usage in the relation to P-PANs. The LRFS-AKE protocol guarantees not only security against classical attacks but also a new additional layer of security against leakage of stored secrets

Network mobility introduces far more complexity than host mobility. To address the extensions needed for network mobility, the IETF NEMO working group has recently standardized the network mobility basic support protocol in RFC 3963. However, in this RFC, it is not mentioned how authentication authorization and accounting (AAA) issues are handled in NEMO environment. Also the use of IPsec to secure NEMO procedures does not provide robustness against leakage of stored secrets. To address this security issue and to achieve AAA with mobility, we propose new handover procedures to be performed by mobile routers and by visiting mobile nodes. These new handover procedures are based on leakage resilient-authenticated key establishment (LR-AKE) protocol.

Network mobility introduces far more complexity than host mobility. Therefore, host mobility protocols such as Mobile IPv6 (MIPv6) need to be extended to support this new type of mobility. To address the extensions needed for network mobility, the IETF NEMO working group has recently standardized the network mobility basic support protocol in RFC 3963. However, in this RFC, it is not mentioned how authentication authorization and accounting (AAA) issues are handled in NEMO environment. Also, the use of IPsec to secure NEMO procedures does not provide robustness against leakage of stored secrets. To address this security issue and to achieve AAA with mobility, we propose new handover procedures to be performed by mobile routers and by visiting mobile nodes. This new handover procedure is based on leakage resilient-authenticated key establishment (LR-AKE) protocol. Using analytical models, we evaluate the proposed handover procedure in terms of handover delay which affects the session continuity. Our performance evaluation is based on transmission, queueing and encryption delays over wireless links

Wireless networks beyond 2G aim at supporting real-time applications such as VoIP. Before a user can start a VoIP session, the end-user terminal has to establish the session using signaling protocols such as H.323 and session initiation protocol (SIP) in order to negotiate media parameters. The time interval to perform the session setup is called the session setup time. It can be affected by the quality of the wireless link, measured in terms of frame error rate (FER), which can result in retransmissions of packets lost and can lengthen the session setup time. Therefore, such protocols should have a session setup time optimized against loss. One way to do so is by choosing the appropriate retransmission timer and the underlying protocols. In this paper, we focus on SIP session setup delay and propose optimizing it using an adaptive retransmission timer. We also evaluate SIP session setup performances with various underlying protocols (transport control protocol (TCP), user datagram protocol (UDP), radio link protocols (RLPs)) as a function of the FER. For 19.2 Kbps channel, the SIP session setup time can be up to 6.12 s with UDP and 7 s with TCP when the FER is up to 10 percent. The use of RLP (1, 2, 3) and RLP (1, 1, 1, 1, 1, 1) puts the session setup time down to 3.4 s under UDP and 4 s under TCP for the same FER and the same channel bandwidth. We also compare SIP and H.323 performances using an adaptive retransmission timer: SIP outperforms H.323, especially for a FER higher than 2 percent

In wireless networks, security is an essential feature that can be provided using a variety of protocols. On the other hand, the security protocols can affect applications to varying degrees depending on the network conditions. In this paper, we propose to evaluate the overhead introduced by the security mechanisms in WLAN such as authentication. To do so, we develop an analytical model based on random errors to evaluate the authentication delay for various error rates taking into account the reliability mechanisms involved. We also measure the authentication delay for WLAN 802.11b using CISCO access point and client cards. We generate the average, minimum and maximum delay for the different authentication configuration available in the CISCO security suite. The analytical and the experimental results are compliant. The major contributor of the authentication delay is the probing time needed to detect the surrounding access point.

The support of IP-based real-time services in the next-generation mobile systems requires the coupling of mobility with quality of service. The mobile node can experience disruptions or even intermittent disconnections of an ongoing real-time session due to handovers. The duration of such interruptions is called disruption time or handover delay and can heavily affect user satisfaction. Therefore, this delay needs to be minimized to provide good quality VoIP services. In this paper, we focus on the network-layer mobility, specifically on mobile Internet protocols (MIP) since they are natural candidates for providing network layer mobility. Using analytical models, we evaluate MIPv4 and MIPv6 and compare their performances in terms of handover delay for VoIP services. To optimize the handover delay, we propose to use the adaptive retransmission timer described in this paper. The results obtained using the adaptive timer technique show that for 3% frame error rate and a 9.6 Kbps channel, the handoff delay is about 0.67 s for MIPv6 and 0.32 s for MIPv4. MIPv4 gives an appropriate support to VoIP services in terms of handover delay but the end-to-end delay may be affected by the triangular routing avoided in MIPv6.

In this paper, the session setup delay of the session initiation protocol (SIP) is studied. The session setup delay is a relevant metric for evaluating real-time services signaling: it has a direct impact on the user satisfaction as the user expects to wait the same time as in GSM or PSTN. The transmissions on both forward and reverse channel are assumed to experience Markovian errors. The session setup delay is evaluated for different transport protocols and with the use of the radio link protocol (RLP). An adaptive retransmission timer is proposed to optimize SIP performances. Using numerical results, we find that SIP over UDP instead of TCP can make the session setup up to 30% shorter. Also RLP reduces drastically the session setup delay down to 8s even in environment with high frame error rate (10%) and significant correlation in the fading process (f/sub D/T=0.02).

The coupling of mobility and quality-of-service with security is a challenge that should be addressed in future wireless overlay systems. The mobility of a node can disrupt or even intermittently disconnect an ongoing real-time session because a secure handover must be performed to ensure continuous connectivity. The duration of the such interruptions is called disruption time or handover delay and can heavily affect the user satisfaction. The handover procedure needs to protect its integrity and confidentiality-otherwise, the packets may be rerouted to a malicious node and the legitimate handover may not be performed. The security procedure to ensure this should not lengthen significantly the handover delay to provide good quality real-time services. In this paper, we focus on the network-layer mobility, specifically, on Mobile Internet protocol version 6 (MIPv6) since it is the natural candidate for providing such mobility in future systems. To solve the problem of on-path attackers and prevent leakage of secrets, we propose a security architecture for MIPv6 based on leakage resilient-authenticated key establishment (LR-AKE) protocol and its cooperation with public key infrastructure. The proposed architecture prevents against on-path attackers which was not addressed in the specifications of MIPv6, and also provides robustness against leakage of secret values. Using analytical models, we evaluate MIPv6 handover delay for real-time services. We identify the crucial factors affecting the handover delay among transmission delays of MIPv6, security and LR-AKE messages, queueing delays and en/decryption delays.

Wireless networks beyond 2G aim at supporting real-time applications such as VoIP. Signalling protocols such as the session initiation protocol (SIP) are used to set up VoIP calls. The session setup time can be affected by the quality of the wireless link, measured in terms of frame error rate (FER), which can result in retransmission of lost packets and can lengthen the session setup time. Therefore, such protocols should have a session setup time optimized against loss. One way to do so is by choosing the appropriate retransmission timer and the underlying protocols. In this paper, we focus on the SIP protocol and evaluate its session setup delay with various underlying protocols (transport control protocol (TCP), user datagram protocol (UDP), radio link protocol (RLP)) as a function of the FER. For a 9.6 Kbps channel, the SIP session setup time can be up to 84.5 s with UDP and 105 s with TCP when the FER is up to 10%. The use of RLP(1,2,3) puts the session setup time down to 2.4 s under UDP and 3.5 s under TCP for the same FER and the same channel bandwidth.