Patent ID: 8522036

Claim:
A method for allowing a receiving device, comprising a security module, to access media services encrypted under at least a control word, said access being subject to at least the presence of a right in said security module, the method comprising: recording, with a processor of the security module, the right in the security module by: receiving an entitlement management message comprising at least said right and verification data; processing the entitlement management message at least to check the verification data; during the processing of said entitlement management message, building a signature value through a plurality of predetermined operations at intervals within said processing; deriving a digest from at least a part of said signature value; and in response to said entitlement management message being valid, recording the right into a rights database together with the digest; and determining, with the processor, the control word by: receiving an entitlement control message comprising an encrypted control word and an access condition referring to said right; processing said entitlement control message at least to verify whether the right referred to by said access condition is present in the rights database; retrieving the digest corresponding to the right referred to by the access condition when the right referred to by said access condition is present in the rights database; and decrypting the encrypted control word using said digest.