METHOD AND APPARATUS FOR ENCRYPTING/DECRYPTING EFFICIENTLY ACCORDING TO BROADCAST ENCRYPTION SCHEME

摘要

A method and an apparatus for encrypting/decrypting efficiently according to a broadcast encryption scheme are provided to eliminate unnecessary encrypting/decrypting processes generated when a disused device does not exist by encrypting a content key with a disused key and decrypting the encrypted content key only when the disused device exists. A decrypting method includes the steps of: determining whether a disused device exists or not among devices having licenses for predetermined contents; and selectively decrypting an encrypted content key with a key for forbidding the disused device to encrypt the predetermined contents according to the determined results. The contents key is used to encrypt the predetermined contents.