Patent ID: 7978848

Claim:
A method, comprising: generating a collection of prime numbers; determining that a rekey is needed for a collection of data blocks that are to be broadcast or multicast to a recipient device; generating a plurality of content encryption keys to encrypt the collection of data blocks, generating the plurality of content encryption keys being based at least on a plurality of prime numbers selected from the collection of prime numbers; publishing the collection of prime numbers; and deriving a single digital rights management (DRM) decryption secret to be sent to the recipient device without sending a plurality of decryption keys for decrypting the collection of data blocks to the recipient device, wherein deriving the single DRM decryption secret is based at least on a scalar multiplication product of the plurality of prime numbers that have been selected for generating the plurality of content encryption keys of the collection of data blocks, and wherein the scalar multiplication product of the plurality of prime numbers used in deriving the single DRM decryption secret enables the plurality of decryption keys to be derived for the collection of data blocks from the single DRM decryption secret.