Binary Information Press
The internet is a relatively convenient environment for promoting the distribution of digital contents. However, over the open internet, a content protection mechanism is extremely required to resist any eavesdropping and modification on the content and the associated license. Cryptography is a general measure to construct content protection. Nevertheless, in the existing schemes, much cost is spent on the management, delivery, and validity verification of cryptographic keys. As the authors know, even marginal cost reductions can lead to competitive advantage in the electronic business.