A memory element is provided in the recording medium that is readable but
not writeable by external devices, and whose content changes each time
select material is recorded onto the medium. The content of this memory
element forms a unique encryption key for encrypting the content
encryption key. This encrypted content encryption key is further
encrypted using a public key that corresponds to a private key of the
intended rendering device. Although the unique encryption key is
determinable by reading and processing the content of the externally
read-only memory element, the decryption of the content encryption key
requires both the unique encryption key and the private key of the
intended rendering device. Because the unique encryption key is based on
a content value of the read-only memory element that is unique to each
recording to the recording medium, a subsequent illicit re-recording of
the original encrypted content material onto the recording medium (a
replay attack) will not provide the same unique encryption key as the
unique encryption key used to originally encrypt the content encryption
key. Because the unique encryption key of the replay attack differs from
the original unique encryption key used to encrypt the content encryption
key, the rendering device will be unable to decrypt the content
encryption key, and thereby will be unable to decrypt the content
material, and the replay attack will fail.