The objective of traitor tracing technique is to enable a broadcaster to identify illegal users from secret keys issued to them. In a broadcast encryption scheme, although a broadcaster can identify a traitor when a secret key is leaked, the decrypted copy is not protected from illegal distribution. In the fingerprinting scheme, a broadcaster can trace illegal users from a pirated copy because each user purchases the copy watermarked by his own fingerprint. However, the transaction to distribute the copy is one-to-one. In this paper, we have proposed a broadcast-type fingerprinting scheme such that only authorized users who have own decryption key can obtain the fingerprinted copy.
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