Patent ID: 7505593

Claim:
A method for disabling at least one traitor receiver in a broadcast encryption system, comprising: examining augmentations of at least one redistributed version of at least one file in a group of files, wherein each authorized receiver acquired decryption keys only for the particular augmentations that it used; for at least one possible receiver and for at least one file, determining a level to which said augmentations correspond to a first set of super codes previously assigned to each authorized receiver; concluding, responsive to said level, that a number of said receivers are traitor receivers; and selectively revoking a number of said receivers concluded to be traitor receivers according to said level; repeating said examining by broadcasting said group of files in said broadcast encryption system by selecting another set of super codes; and wherein said first set of super codes and said another set of super codes are selected to reduce number of said authorized receivers concluded to be traitor receivers by examining augmentations of additional redistributed files in said group of files; and wherein said first set of super codes and said another set of super codes are selected such that said 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.