A data recording/reproducing method wherein encrypted digital data
obtained by subjecting digital data to first encrypting by using a
contents key and encrypted contents key obtained by subjecting the
contents key to second encrypting are recorded on a recording medium, the
encrypted digital data and the encrypted contents key, having been
recorded, are reproduced, and the encrypted digital data is decrypted by
using the contents key obtained by decrypting the encrypted contents key,
thereby to obtain the digital data.