Data record media

摘要

An optical disk (D) has a first record layer (L1) and a second record layer (L2) having two recording formats. Encrypted data is recorded on the first record layer (L1). Encrypting key data is recorded on the second record layer (L2). The encrypting key data is used for decoding the encrypted data. This recording technique makes easy reproduction of the recorded data quite difficult. If data recorded on a bit-formed portion can be reproduced by any means, the data signal recorded on the optical disk cannot easily be reproduced.