US 2013/0279694 A1 · SYSTEM AND METHOD TO RECORD ENCRYPTED CONTENT WITH ACCESS CONDITIONS

Abstract

A television event may be consumed after been stored in a mass memory of a multimedia unit, but still fully relies on the security of a secure device. A conversion of a received content aims at firstly descrambling the content using control words included in entitlement control messages and immediately re-encrypting the descrambled content by a unique key generated specifically for this content. Access conditions attached to the entitlement control message containing the control word are temporarily stored and once the decryption is terminated, the secure device produces an information block. This information block containing for example access conditions and an identifier of the content is either stored into a secure memory of the secure device or stored in the mass memory with the encrypted content. The unique key is made up of a combination of a root key specific to the secure device and the information block.

Claims18

Dependent claims

A system for broadcasting and recording content digital data comprising:

a managing center adapted to prepare and transmit scrambled content SC digital data together with entitlement control messages including at least one control word and access conditions AC relative to the content C;
a multimedia unit configured to receive and record, in a mass memory, the content C digital data;
a secure device connected to the multimedia unit and adapted to descramble the scrambled content SC digital data with the control word, the secure device being at least configured to:
generate a content specific key KC=KR⊕B obtained by carrying out a cryptographic operation ⊕ combining a root key KR specific to the secure device and an information block B relative to the content C digital data,
encrypt the previously descrambled content C digital data with the content specific key KC, obtaining an encrypted content EC=(C)KC, and
forward the encrypted content digital data EC together with the information block B to the mass memory of the multimedia unit for recording.

3 more elements

A method for recording broadcast content C digital data in a mass memory of a multimedia unit, said content C digital data being received by the multimedia unit in a scrambled form together with entitlement control messages ECM comprising at least one control word CW and access conditions AC relative to the content C, the method comprising:

descrambling, by a secure device connected to the multimedia unit, the received scrambled content SC digital data with the control word CW, the descrambling comprising:
generating by the secure device, a content specific key KC=KR⊕B obtained by carrying out a cryptographic operation ⊕ combining a root key KR specific to the secure device and an information block B relative to the content C digital data,
encrypting the previously descrambled content C digital data with the content specific key KC, obtaining an encrypted content EC=(C)KC, and
forwarding the encrypted content digital data EC together with the information block B to the mass memory of the multimedia unit for recording.

1 more element

A secure device, connected to a multimedia unit including a mass memory storing scrambled content SC digital data together with entitlement control messages including at least one control word and access conditions AC relative to the content C, adapted to descramble the scrambled content SC digital data with a control word, the secure device being at least configured to:

generate a content specific key KC=KR⊕B obtained by carrying out a cryptographic operation ⊕ combining a root key KR specific to the secure device and an information block B relative to the content C digital data,
encrypt the previously descrambled content C digital data with the content specific key KC, obtaining an encrypted content EC=(C)KC, and
forward the encrypted content digital data EC together with the information block B to the mass memory of the multimedia unit for recording.

Dependencies are inferred from the claim text.

System and method to record encrypted content with access conditions

Life of this patent

System and method to record encrypted content with access conditions

Life of this patent

Abstract

Claims18