COMPUTER SCIENCE EN
security_in_adhoc_and_sensor_network.pdf

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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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44 M. Ramkumar B , the attacker can compute all 2 m SCs used for computing K AB . The probability that the attackers pool of secrets exposed from n entities can be used to compute K AB (or all 2 m SCs can be computed by the attacker) is p ( n ) = (1 ) 2 m (1 e n / M ) 2m . (11) In general, to realize an ( n , p )-secure KSSC (or p ( n ) = p ) with mini- mum k = k = m M , we can choose m = log(1 /p ) 2 log 2 M = n log 2 k = 1 2 log 2 2 n log(1 /p ) (12) For example, for m = 32 and M = 2 16 , (and k = 2 21 ) we have (1) p (45000) 2 64 - or an attacker with access to secrets of 45,000 entities can compute only one in 2 64 illegitimate pairwise secrets; and (2) p (85000) = 2 30 - an attacker with access to secrets assigned to 85,000 entities can compute one in a billion pairwise secrets. 3.2.4. Blom’s Scheme vs KSSC Note that improving the collusion resistance n of Blom’s scheme mandates a linear increase in computational and storage overhead. For achieving n - security every mobile device needs to store n + 1 secrets. Computing any shared secret calls for 2( n +1) finite-field multiplications and one finite-field exponentiation. Even for n of the order of a few hundreds, the computa- tional overhead for Blom’s scheme will be comparable to that of public key schemes. On the other hand, for KSSC the computational overhead - comput- ing m = log(1 /p ) 2 log 2 SCs - is independent of n . Only the storage overhead k = m ( M + 1) (for m secrets and mM SCs) increases linearly with n . For example, the scheme with m = 32 and M = 2 16 is ( n = 45000 , p = 2 64 )- secure. To realize a scheme which is ( n = 90000 , p = 2 64 )-secure, all we need to do is to double M . The value m (which determines the computa- tional overhead) remains the same ( m = 32). Only the storage overhead mM is increased from k = 2 21 to k = 2 22 . 3.3. A “Nonscalable” Key Predistribution Scheme Scalable KPSs like Blom’s KPS and KSSC achieve unlimited scalability by tolerating susceptibility to collusions. On the other hand nonscalable 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 45 key predistribution schemes, which are not susceptible to collusions, have limitations on the total network size N (the number of entities that can be inducted by the KDC). The most well known of nonscalable KPSs is the “basic” KPS. To support a network of N entities, the KDC chooses ( N 2 ) pairwise secrets and provides every node with N 1 secrets. The reason that the scheme does not scale well is due to the O ( N ) storage requirement for each node.
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  • Spring '12
  • Kushal Kanwar
  • Public key infrastructure, ........., Public-key cryptography, Pretty Good Privacy

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