Key transport tamper protection
First Claim
1. A method for protecting the digital output signal of a security module, comprising the steps of:
- (a) receiving a scrambled digital signal from a source external to said security module;
(b) recovering at least one transport scramble control flag from the scrambled digital signal;
(c) generating a descrambling key in response to the transport scramble control flag;
(d) descrambling, using said descrambling key, said received scrambled signal to generate a descrambled signal;
(e) monitoring the at least one transport scramble control flag;
(f) generating a scrambling key in response to said monitored at least one transport scramble control flag; and
, (g) scrambling said descrambled signal using said scrambling key to generate a rescrambled signal.
5 Assignments
0 Petitions
Accused Products
Abstract
A method for protecting the digital output signal of a security module, comprising the steps of: receiving a scrambled digital signal from a source external to said security module, recovering at least one transport scramble control flag from the scrambled digital signal, descrambling said received scrambled signal to generate a descrambled signal, monitoring the at least one transport scramble control flag, generating a scrambling key in response to said monitored at least one transport scramble control flag, and scrambling said descrambled signal using said scrambling key to generate a re-scrambled signal. The present invention also includes a conditional access system comprising a host device and a security device coupled to the host device, such that the security device includes at least one transport scramble control flag modification circuit. By monitoring the transport scramble control flag as content passes through the security module, protection of the content can be securely maintained.
19 Citations
14 Claims
-
1. A method for protecting the digital output signal of a security module, comprising the steps of:
-
(a) receiving a scrambled digital signal from a source external to said security module;
(b) recovering at least one transport scramble control flag from the scrambled digital signal;
(c) generating a descrambling key in response to the transport scramble control flag;
(d) descrambling, using said descrambling key, said received scrambled signal to generate a descrambled signal;
(e) monitoring the at least one transport scramble control flag;
(f) generating a scrambling key in response to said monitored at least one transport scramble control flag; and
,(g) scrambling said descrambled signal using said scrambling key to generate a rescrambled signal. - View Dependent Claims (2, 3, 4)
-
-
5. A conditional access system comprising:
-
a host device; and
a security device coupled to the host device, wherein the security device comprises at least one transport scramble control flag monitoring circuit for monitoring at least one transport scramble control flag transmitted from the host device to the security device, and generating a scrambling key in response thereto. - View Dependent Claims (6, 7, 8, 9, 10)
-
-
11. A method for protecting the digital output signal of a security module, comprising the steps of:
-
(a) receiving a digital signal from a source external to said security module;
(b) recovering at least one transport scramble control flag from the digital signal;
(c) monitoring the at least one transport scramble control flag within the security module; and
,(d) verifying the at least one transport scramble control flag at the output of the security module. - View Dependent Claims (12, 13)
-
-
14. A method for protecting the digital output signal of a security module, comprising the steps of:
-
(a) receiving a digital signal from a source external to said security module;
(b) inserting at least one transport scramble control flag into the digital signal within the security module;
(c) monitoring the at least one transport scramble control flag within the security module; and
,(d) verifying the at least one transport scramble control flag at the output of the security module.
-
Specification