Patent ID: 7503077

Claim:
An information storage medium (ISM) comprising means storing: an encrypted content; encryption key information needed in a process of decoding the encrypted content; an associated ISM ID, said associated ISM ID being an identifier uniquely assigned to the ISM; and a first list identifying revoked ISM ID's, said first list having an associated first version date and an associated tampering check value for checking whether said first list is untampered, wherein, the ISM is adapted for operation with an information processing apparatus, said apparatus having means for executing a process for playing back content stored on the ISM, a memory for storing a second list identifying revoked ISM ID's, said second list having an associated second version date, means for checking whether the associated ISM ID is identical to a revoked ISM ID identified in said second list, means for disabling the process for playing back content when the associated ISM ID is identical to a revoked ISM ID identified in said second list, means for checking the associated tampering check value to determine whether the first list identifying revoked ISM ID's is untampered, and means for updating said memory, by replacing said second list with the first list, said means for updating said memory enabled to only operate when the first list is untampered and the associated first version date is later than said associated second version date.