KEY INFORMATION GENERATION METHOD

摘要

By using a domain key, encrypted content key information is sequentially decrypted (ST203-1) and first data is extracted (ST203-2). The extracted first data is compared to data for partial inspection (ST203-4). The first data in the encrypted state is extracted from each of m encrypted content key information (ST203-6) and the extracted sequential data containing m check values is subjected to a predetermined calculation so as to generate second data (ST203-8). The second data is compared to the data for entire inspection contained in the domain key information (ST203-11). If the first data coincides with the partial inspection data (ST203-5) and the second data coincides with the entire inspection data (ST203-12), it is judge that no alteration has been performed.