413 storage and out of network bandwidth overhead out

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4.1.3. Storage and Out-of-Network Bandwidth Overhead Out-of-network bandwidth overhead is for purposes of one-time distribution of secrets/public values to the mobile devices by the KDC. Typically, as such values are also stored by the mobile devices, it is also the storage overhead for devices. For schemes based on asymmetric primitives, the storage overhead is negligible (each device will need to store its private key and certificate). The storage overhead for OTS schemes is higher than public key schemes. Corresponding to every commitment (which can be used only for one signature) each device will need to store a few tens of hashes from a Merkle hash tree (to authenticate the commitment), and the private key. For key predistribution schemes, the out-of-network overhead and stor- age can be substantial. For scalable KPSs like Blom’s scheme and KSSC, the storage overhead is O ( n ), irrespective of the network size N . For MLS (which is not susceptible to collusions) the storage overhead is O ( N ). 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
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Key Distribution 49 4.2. The Cost of Resources Obviously, different resources have different associated costs. For mobile devices it is advantageous to reduce computational and in-network band- width overhead in the interest of prolonging battery life. Out-of-network bandwidth overhead is however, not a severe limitation. For example, during induction, mobile devices could be provided with one secret over a secure channel. One secret could be included in the SIM card provided by Tingular to its subscribers. All other values could be encrypted using the secret, and delivered even over the postal network, by mailing optical disks or flash memory cards, or downloaded from Tingular’s FTP site. Furthermore, while storage overhead for mobile devices was a concern a few years ago, it is obviously not a severe concern now with the dramatically increasing storage capabilities of current mobile devices. Any mobile device can easily afford several GBs of pluggable flash storage. Using a few tens (or even hundreds) of MBs of that storage for keys/certificates is indeed reasonable. Even while the computational abilities of mobile devices has increased to such extents that most devices will be able to support asymmetric com- putations, it is indeed desirable to limit the use of expensive asymmetric primitives to the extent possible. Apart from placing substantially higher demands on computation and bandwidth, indiscriminate use of asymmet- ric cryptographic primitives can also lead to simple denial of service (DoS) attacks. For example, attackers can simply send packets with random “sig- natures.” It is only after expensive computations necessary for verification,
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  • Spring '12
  • Kushal Kanwar
  • Public key infrastructure, ........., Public-key cryptography, Pretty Good Privacy

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