Coin-based Anonymous Fingerprinting Scheme with Automatic Identification of Redistributors

As the markets of digital contents over computer networks become more popular, illegal redistribution of contents by a buyer becomes the more serious problem. To deter illegal redistribution, various fingerprinting schemes have been proposed. The fingerprinting schemes enable merchants to embed information which identifies the original buyer to the purchased content. Identifying the original buyer from the confiscated content deters buyers from redistributing contents. To protect honest buyer’s privacy, a certain type of fingerprinting schemes, called an anonymous fingerprinting scheme, allows the buyers purchasing fingerprinted contents anonymously. The anonymous fingerprinting schemes involve the registration center to which every buyer registers before purchasing contents. In most of the anonymous fingerprinting schemes, the merchant has to cooperate with the registration center to identify the buyer from the confiscated content. To identify the buyer speedily, it is desirable that the merchant needs not to cooperate with the registration center. This feature is called the automatic identification. In this paper, an efficient anonymous fingerprinting scheme with automatic identification is proposed. To realize the automatic identification, personal information of the buyer is embedded correctly in the purchased content retaining the anonymity of the buyer. Then, the merchant can identify the buyer by himself/herself when a copy of the purchased content is confiscated. Compared with the previous anonymous fingerprinting scheme with automatic identification, although the proposed scheme requires more number of registrations, the total amount of computation is smaller than the previous schemes.