Method of and system for encrypting digital data, method of and apparatus for reproducing digital data, and computer product

摘要

There is provided an input unit which reads copyright digital data stored in a recording medium such as a CD-ROM, an operation unit which performs encryption of digital data based on an encryption algorithm from a plurality of encryption algorithms. A file unit outputs the encrypted digital data and an index value and the encryption operation equation generation parameter into one file. A reproducing apparatus obtains an encryption operation equation from the index value and the encryption operation equation generation parameter in this same file and reproduces the encrypted digital data.