Optimal broadcasting encryption with free riders
Author(s)
Advisor
Selçuk, Ali AydınDate
2006Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Broadcast encryption schemes allow a center to broadcast encrypted messages
so that each particular message can only be decrypted by a set of privileged
receivers designated for it. The standard technique is to distribute keys to all receivers
at the beginning and to use only the necessary keys to encrypt the message
for each particular broadcast. The number of encryptions needed constitutes the
transmission cost in broadcast encryption schemes. The most efficient scheme in
terms of transmission cost published so far is the subset difference (SD) scheme. It
is possible to reduce the transmission overhead of a broadcast encryption scheme
by allowing a number of free riders to be able to decrypt the message although
they are not privileged. However, unless the free riders are chosen cleverly, the
cost may even increase. In this thesis, we deal with the problem of choosing a
given number of free riders effectively to reduce the transmission overhead in SD
scheme. We first present three greedy algorithms. First algorithm has a fast
execution, the second one is slower but has lower transmission overhead, and the
last one has a trade-off between running time and transmission cost. Then we
present two algorithms which find the minimum transmission overhead possible
given a free rider quota. The experiments we conduct show that the transmission
cost can be significantly reduced.