An efficient traitor tracing scheme for broadcast encryption

An efficient traitor tracing scheme for broadcast encryption is proposed. Its security depends on the difficulty of discrete logarithm problem and is equivalent to ElGamal public-key cryptosystem even when subscribers collude. The proposed scheme is the first one which satisfies all the following features: the tracing algorithm is black box tracing; all the traitors are identified from a captured pirate decoder; the data supplier can encrypt the contents such that only a specific subset of subscribers´ decoders can decrypt it; the encryption algorithm is public-key