Deterring traitor using double encryption scheme

Traitor is a legitimate user in a content distribution system who facilitates illegal content access to unauthorized party. Naturally, there are two strategies that are likely used by the traitors to do violations. Firstly, the traitors may attempt to extract the decryption keys to construct a pirate decoder. Secondly, they may legally decrypt the content and then illegally redistribute the decrypted content for their own benefits. We propose a content protection scheme to deter both piracy strategies. However, if a pirate decoder or content is discovered, the scheme is still able to identify the real traitors without incriminating innocent users. Thus, our scheme preserves security for the content provider and privacy for the users in the traitor tracing context.