Method, system and program product for managing a size of a key management block during content distribution

A method for managing a size of a key management block (KMB) during content distribution, comprising the steps of:

• providing a first KMB corresponding to a first subtree of devices, and content encrypted with a title key, wherein the title key is encrypted with a first key encrypting key that is protected within the first KMB;
• determining whether a size of the first KMB exceeds a predetermined threshold;
• providing a second KMB corresponding to a second subtree of devices, wherein the second KMB includes an entry revoking the first subtree of devices, and wherein the second KMB is smaller than the first KMB;
• migrating compliant devices from the first subtree of devices to the second subtree of devices;
• and
• re-encrypting the title key with a second key encrypting key as recovered from the second KMB.

A system for managing a size of a key management block (KMB) during content distribution, comprising:

• a system for receiving a first KMB corresponding to a first subtree of devices, and content encrypted with a title key;
• a system for receiving a second KMB corresponding to a second subtree of devices, wherein the second KMB is smaller than the first KMB, and wherein the second KMB includes an entry revoking the first subtree of devices;
• and
• a system for migrating compliant devices from the first subtree of devices to the second subtree of devices based on migration data.

A program product stored on a recordable medium for managing a size of a key management block (KMB) during content distribution, which when executed, comprises:

• program code for receiving a first KMB corresponding to a first subtree of devices, and content encrypted with a title key;
• program code for receiving a second KMB corresponding to a second subtree of devices, wherein the second KMB is smaller than the first KMB, and wherein the second KMB includes an entry revoking the first subtree of devices;
• and
• program code for migrating compliant devices from the first subtree of devices to the second subtree of devices based on migration data.