Abstract: A method of providing key information from a sender to one or more receivers, the method comprising: obtaining initial key information comprising a plurality of units that assume respective values; forming encoded key information from the initial key information, wherein the encoded key information comprises a plurality of encoded units that correspond to respective units of the initial key information, wherein said forming comprises, for each unit of the initial key information, selecting an encoding from a plurality of invertible encodings associated with said unit and encoding said value assumed by said unit with said selected encoding to form the corresponding encoded unit; and providing the encoded key information to said one or more receivers.

Abstract: There is disclosed a method of controlling use of encrypted content by a plurality of client terminals each provided with a digital rights management (DRM) client and a content decryption module separate to the DRM client. First key information is provided for use by one or more selected ones of the DRM clients, and second key information is provided for use by one or more selected ones of the content decryption modules. Content key information is encrypted to form encrypted content key information such that the selected ones of the content decryption modules are enabled by the second key information to recover the content key information from the encrypted content key information. The encrypted content key information is further encrypted to form super-encrypted content key information such that the selected ones of the DRM clients are enabled by the first key information to recover the encrypted content key information from the super-encrypted content key information.

Abstract: A method of obtaining descrambling information at a receiver, the descrambling information for enabling descrambling of scrambled content. A provider verification key is used to access a software image, which has been secured by a provider using a provider signature key corresponding to the provider verification key. A secured version of the descrambling information is received. The accessed software image is used to obtain virtual descrambling information from the secured version of the descrambling information and is provided as inputs to a cryptographic function to produce a given output comprising said descrambling information.

Abstract: A fingerprinting method. For each round in a series of rounds: providing to each receiver in a set of receivers a version of a source item of content, the source item of content corresponding to the round. For the round there is a corresponding part of a fingerprint-code for the receiver, the part includes one or more symbols. The version provided to the receiver represents those one or more symbols. One or more corresponding symbols are obtained from a suspect item as a corresponding part of a suspect-code. For each receiver in the set of receivers, a corresponding score that indicates a likelihood that the receiver is a colluding-receiver is updated.

Abstract: A method of providing key information from a sender to one or more receivers, the method comprising: obtaining initial key information comprising a plurality of units that assume respective values; forming encoded key information from the initial key information, wherein the encoded key information comprises a plurality of encoded units that correspond to respective units of the initial key information, wherein said forming comprises, for each unit of the initial key information, selecting an encoding from a plurality of invertible encodings associated with said unit and encoding said value assumed by said unit with said selected encoding to form the corresponding encoded unit; and providing the encoded key information to said one or more receivers.

Abstract: A fingerprinting method. For each round in a series of rounds: providing to each receiver in a set of receivers a version of a source item of content, the source item of content corresponding to the round. For the round there is a corresponding part of a fingerprint-code for the receiver, the part includes one or more symbols. The version provided to the receiver represents those one or more symbols. One or more corresponding symbols are obtained from a suspect item as a corresponding part of a suspect-code. For each receiver in the set of receivers, a corresponding score that indicates a likelihood that the receiver is a colluding-receiver is updated.

Abstract: There is disclosed a method of controlling use of encrypted content by a plurality of client terminals each provided with a digital rights management (DRM) client and a content decryption module separate to the DRM client. First key information is provided for use by one or more selected ones of the DRM clients, and second key information is provided for use by one or more selected ones of the content decryption modules. Content key information is encrypted to form encrypted content key information such that the selected ones of the content decryption modules are enabled by the second key information to recover the content key information from the encrypted content key information. The encrypted content key information is further encrypted to form super-encrypted content key information such that the selected ones of the DRM clients are enabled by the first key information to recover the encrypted content key information from the super-encrypted content key information.

Abstract: A method of obtaining descrambling information at a receiver, the descrambling information for enabling descrambling of scrambled content. A provider verification key is used to access a software image, which has been secured by a provider using a provider signature key corresponding to the provider verification key. A secured version of the descrambling information is received. The accessed software image is used to obtain virtual descrambling information from the secured version of the descrambling information and is provided as inputs to a cryptographic function to produce a given output comprising said descrambling information.