Patent ID: 7305711

Claim:
A system comprising: a first entity to generate a set of N asymmetric key pairs, to create J sets of private keys by selecting a unique combination of L private keys from the N asymmetric key pairs for each created set, and to distribute the sets of private keys, where N, J, and L are natural numbers; a second entity to produce protected content including encrypted content and a public key media key block, by encrypting a symmetric content key with each public key in the set of asymmetric key pairs to form the public key media key block and by encrypting a content title with the symmetric content key to form the encrypted content; and a playback device to store one of the J sets of private keys, to receive the protected content, and to decrypt and play the content title stored in the protected content when a selected one of the set of private keys stored by the playback device successfully decrypts the encrypted symmetric content key stored in the public key media key block of the received protected content.