An Improved Traitors Tracing Scheme Based on ELGamal

The flaw of traitor tracing schemes based on traditional ElGamal is that cannot resist convex combination attack. On this point this paper raises an improved ElGamal scheme, which shorten the length of the private key. The new scheme uses the users private key and the header h(s, r) to computer session keys. It is worth mentioning that the user's private key has relation with the header h(s, r), so the improved scheme has good revocability. The results show that the security of the improved scheme is enhanced in comparison with the traditional traitor tracing scheme.