Cryptography – Video cryptography – Video electric signal modification
Reexamination Certificate
2009-09-02
2011-10-11
Hoffman, Brandon (Department: 2433)
Cryptography
Video cryptography
Video electric signal modification
Reexamination Certificate
active
08036382
ABSTRACT:
In a conditional access system, a headend transmits content to one or more receivers in encrypted transport streams. The system provides a multi-layer security architecture, rendering the system resistant to key replay attacks; if one layer is circumvented, subsequent layers remain intact. A first layer prevents unencrypted keys from being recorded by shielding the unencrypted keys from users and encrypting the path from the receiver's conditional access module to the transport decryption module; a second layer prevents a key recorded on one receiver from being played back to the transport decryption module on a second receiver; a third layer prevents a user from decrypting transport streams without the encryption module by encrypting the stream a second time prior to being passed through any user-accessible memory or processor.Event tables are transmitted with the transport stream, either unencrypted for immediate use or encrypted, to prevent unauthorized use.
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Goodman Andrew M.
Platt David C.
Zenchelsky Daniel
Hickman Palermo & Truong & Becker LLP
Hoffman Brandon
Shah Varun A.
TiVo Inc.
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