All the existing traitor tracing schemes can trace at least a traitor when the number of traitors is not beyond a certain predefined value. However

how to prevent traitors from colluding a valid key is a open problem. A new traitor tracing scheme was presented

in which traitors can not get a valid key by conspiracy

no matter how many traitors there were because each user’s decryption key was independent of any others. Further

our scheme can determine a traitor in speediness and accuracy

thus it can reach a better determent to those potential bad users. Meanwhile

compared with present schemes

this scheme has a higher transmission efficiency.