A recording apparatus generates key information based at least on contents reproduction
permission information, encrypts contents based on the key information, and records
the encrypted contents and recording date/time information on a recording medium.
A reproducing apparatus reads the encrypted contents and the recording date/time
information from the recording medium, acquires reproduction date/time information
on the encrypted contents and, based on the recording date/time information that
was read, the reproduction date/time information, and reproduction permission limit
information on the encrypted contents, generates contents reproduction permission
information indicating that the encrypted contents maybe reproduced. The reproducing
apparatus generates key information based at least on the contents reproduction
permission information and decrypts the encrypted contents that were read.