A method for disabling a traitor receiver in a broadcast encryption system
includes examining augmentations of at least one redistributed version of
a file in a group of files, wherein each authorized receiver acquired
decryption keys only for the particular augmentations that it used. A
level to which the augmentations correspond to a first set of super codes
previously assigned to each authorized receiver is determined. A
conclusion is drawn regarding the number of receivers that are traitor
receivers. The receivers concluded to be traitor are selectively revoked.
The process is repeated by selecting another set of super codes; selected
to reduce the number of authorized receivers concluded to be traitor
receivers. The sets of super codes are selected such that the number is
made larger to achieve quicker revocation of a traitor receiver at the
cost of increasing chance of an incorrect revocation of an innocent
receiver.