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USENIX Technical Program - Abstract - Smartcard 99
Beyond Cryptographic Conditional Access
David M. Goldschlag and David W. Kravitz, Divx
Abstract
Conditional access (CA) systems manage chargeable content (e.g.,
movies). Traditional CA systems use a smartcard as a cryptographic
component that decrypts broadcast content for authorized recipients.
Since that approach protects content by protecting cryptographic keys,
it has two inherent weaknesses: It relies on the smartcard to protect
universal secrets (i.e., the broadcast keys); and it cannot protect
content from redistribution. This paper describes a non-cryptographic
conditional access system, where instead of protecting content
directly, the content's identity is inserted as a watermark in the
content and the CA smartcard is used as a licensing authority to
authorize the display device to display watermarked content. This
approach places a lower security burden on individual smartcards, and
protects against the use of redistributed content.
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Technical Program