We study the number of encryptions necessary to revoke a set of users in the complete subtree scheme (CST) and the subset-difference scheme (SD). These are well-known tree based broadcast encryption schemes. Park and Blake in: Journal of Discrete Algorithms, vol. 4, 2006, pp. 215--238, give the mean number of encryptions for these schemes. We continue their analysis and show that the limiting distribution of the number of encryptions for these schemes is normal. This implies that the mean numbers of Park and Blake are good estimates for the number of necessary encryptions used by these schemes.
© 2008 Christopher Eagle, Zhicheng Gao, Mohamed Omar, Daniel Panario, Bruce Richmond
Eagle, C., Gao, Z., Omar, M., Panario, D., Richmond, B. Distribution of the Number of Encryptions in Revocation Schemes for Stateless Receivers. Fifth Colloquium on Mathematics and Computer Science, Discrete Mathematics and Theoretical Computer Science, pp. 195-206 (2008).