A method and apparatus for restricting the use of a disc are provided. In
this method, first, lead-in data is read out from a loaded disc. Then, a
user key is read out from a lead-in area of the disc. Thereafter, the
user key undergoes authentication based on a user key received from a
host. The authentication is performed by comparing a random number
produced by a disc drive with a decrypted random number obtained by the
disc drive decrypting a random number encrypted by the host. Accordingly,
the use of the disc by an unauthorized third person is restricted, thus
preventing a leakage of personal information and a protection of the
copyrights of data.