Research Of Traitor Tracing Technology

The concept of traitor tracing was first introduced by Chor, Fiat and Naor. Traitor tracing could be used in some application fields such as digital copyright protection, charged television, CD/DVD distribution, multimedia protection, file protection, secure email, Internet TV etc. Since the concept of Traitor tracing was introduced, many domestic and foreign scholars have conducted the study. Many new traitor tracing schemes with flexible designs have been proposed. In addition, some traitor tracing schemes having special functions also have been proposed. Traitor tracing is a new research field in cryptography. The main contribution of the thesis is summarized as follows:We proposed a traitor tracing scheme based on Luc public-key cryptosystem. Comparing with existing schemes, we gain the increase in security. The scheme can support more useful functions. The scheme is asymmetric. The scheme supports black-box tracing. The user's key contains the data supplier's signature which makes the tracing more persuasive. The user can choose public key and partial private key, which is more in line with the reality. The user can join or withdrawal system at any time. When discovering the illegal user and the number of collusive users are less than threshold k, the system can revoke the traitor but the legitimate user's key does not need to change. The user's key contains his own identity information that can make legitimate user not reluctantly to leak his key to other users.We studied the traitor tracing scheme proposed by Boneh in 2008. In this scheme the length of the ciphertext is constant. Then we improved the scheme by using mix-key. The improved scheme not only retains some advantages of the original scheme which contain the length of ciphertext is constant and the black-box traitor tracing algorithm but also overcomes the disadvantage of the original scheme that there is imperfect private decoder. In the improved scheme there is no imperfect private decoder which refers to the private decoder that only can correctly decrypts a few well-formed ciphertexts. This will reduce the length of the fingerprint code and improve the efficiency of the original system.