Satoshi Itami

Character string retrieval system using index and unit for making the index

Unauthorized use prevention method for optical disks, optical disk having unauthorized use prevention function, and optical disk apparatus

System for decrypting encrypted software

Optical disk having an erased-state indicator and optical disk apparatus for reducing frequency of disk erasing operation

Optical disk and method of preventing fraudulent use of optical disk rotation synchronous control system

Software processing apparatus writing software to a medium only if identification information in the software corresponds to identification information in the medium

Preventing unauthorised use of optical disc e.g. CD-ROM - comparing first information read out from area of disc inaccessible to user with second information concerning authentic disk

Removable storage medium and computer system using the same

Data management device and data storage medium

Optical information recording/reproducing apparatus having a composite prism with a plurality of emission surfaces