The server may be distributed or replicated on

Info icon This preview shows pages 31–33. Sign up to view the full content.

View Full Document Right Arrow Icon
message to the AAA server. The server may be distributed or replicated on several nodes in the case of wireless ad hoc networks. If the server au- thenticates the supplicant and accepts the request, it generates Pairwise Master Key (PMK), which is distributed to authenticator and supplicant using EAP messages. After authentication from server, the authenticator sets the port for the supplicant to the “authorized” state and normal traffic is allowed. After successful distribution of the encryption key (PMK) and authen- tication of supplicant using 802.1X, the supplicant (mobile device) and the authenticator (peer mobile device) mutually authenticate each other. This process is based on the four-way handshake. The four-way handshake is ini- tiated when the two nodes intend to exchange data. Although an encyption Copyright © 2010. World Scientific Publishing Company. All rights reserved. May not be reproduced in any form without permission from the publisher, except fair uses permitted under U.S. or applicable copyright law. EBSCO Publishing : eBook Collection (EBSCOhost) - printed on 2/16/2016 3:46 AM via CGC-GROUP OF COLLEGES (GHARUAN) AN: 340572 ; Beyah, Raheem, Corbett, Cherita, McNair, Janise.; Security in Ad Hoc and Sensor Networks Account: ns224671
Image of page 31

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Authentication and Confidentiality in Wireless Ad Hoc Networks 19 key PMK is available to both the supplicant and the authenticator, this key is meant to last the entire session and should be exposed as little as possible. The purpose of four-way handshake is to use the PMK and establish two more keys called the Pairwise Transient Key (PTK) and Group Temporal Key (GTK). The first message of the four-way handshake is transmitted by the au- thenticator to the supplicant which consists of ANonce. The supplicant uses this ANonce and readily available fields: Supplicant nonce (SNonce); Authenticator MAC address; and Supplicant MAC address, to generate the PTK using cryptographic hash function. The second message of the handshake is transmitted by the supplicant to the authenticator consisting of SNonce and Message Integrity Code (MIC), which is encrypted using PTK. The authenticator is then able to generate the PTK and GTK. The attached MIC is decrypted using the generated PTK. If the MIC is success- fully decrypted, then the authenticator and the supplicant have successfully authenticated each other (Mutual Authentication). This is because the au- thenticator’s generated PTK will only match the PTK transmitted by the supplicant if the two share the same PMK. Third message is transmitted by the authenticator consisting of GTK and MIC. The Last message of four- way handshake is the acknowledgement transmitted by the supplicant. The two nodes can exchange the data after successful four-way handshake. PTK is used to generate Temporal Key (TK), which is used to encrypt unicast messages, while the GTK is used to encrypt broadcast and multicast messages. The four-way handshake (shown in Figure 5) involves generation and distribution of these keys between supplicant and authenticator and also leads to the mutual authentication of the two.
Image of page 32
Image of page 33
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern