Disabling a cleartext control word loading mechanism in a conditional access system
AssigneeIrdeto Corporate B.V.
InventorAntonius Johannes Petrus Maria Van De Ven
Life of this patent
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Abstract
Various embodiments enable a chipset of a receiver of a conditional access system to block cleartext control words provided to the chipset from being used to descramble content. Hereto the chipset comprises a trigger module configured to obtain a disable command that is received with an encrypted Chip Set Session Key (CSSK) and, if the disable command is obtained, have the chipset block any cleartext control word.
Claims15
A chipset for obtaining a control word to descramble scrambled content in a content descrambler, the chipset comprising
- one or more inputs for receiving a cleartext control word, a first disable instruction, an encrypted Chip Set Session Key (hereinafter “CSSK”) and an encrypted first control word;
- a first memory configured to store a Chip Set Unique Key (hereinafter “CSUK”);
- a first decryptor configured to decrypt the encrypted CSSK using the CSUK from the first memory, the chipset being configured to store the obtained CSSK in a second memory;
- a second decryptor configured to decrypt the encrypted first control word using the CSSK from the second memory, the chipset further being configured to store the obtained first control word in a third memory for use by the content descrambler;
- a blocking module configured to conditionally store the cleartext control word in the third memory for use by the content descrambler, the blocking module further configured to block the cleartext control word from being stored in the third memory if the first disable instruction is received;
- and
- a trigger module configured to obtain a disable command that is received with the encrypted CSSK and, if the disable command is obtained, provide the disable command to the blocking module,
- wherein the blocking module is further configured to block any cleartext control word from being stored in the third memory if the disable command is received.
A method for use in a chipset for blocking a cleartext control word from being used to descramble scrambled content in a content descrambler, the method comprising:
- receiving an encrypted Chip Set Session Key (hereinafter “CSSK”) and receiving an encrypted first control word;
- decrypting the encrypted CSSK using a Chip Set Unique Key (hereinafter “CSUK”) stored in a first memory and storing the obtained CSSK in a second memory;
- decrypting the encrypted first control word using the CSSK from the second memory and storing the obtained first control word in a third memory for use by the content descrambler;
- obtaining a disable command that is received with the encrypted CSSK;
- and
- if the disable command is obtained, blocking any cleartext control word received in the chipset from being stored in the third memory for use by the content descrambler.
Dependencies are inferred from the claim text.