A method of transmitting and recording digital data scrambled using a control
word.
The scrambled data is transmitted together with the control word, and the method
includes encrypting the control word with a first key. The encrypted control word
is transmitted and received, and then decrypted with a decoder that includes an
equivalent of the first key. The control word is re-encrypted with a second key
stored in a portable support device that is received by the decoder, and the portable
support device may be used with any suitable decoder. The re-encrypted control
word and the scrambled digital data are recorded on a digital recording medium.
An apparatus for transmitting and recording digital data scrambled using a control
word. The scrambled data is transmitted together with the control word, and the
apparatus includes a transmitter that encrypts the control word with a first key
and transmits the encrypted control word. A decoder receives the encrypted control
word and decrypts the control word. A portable support device including a second
key is received by the decoder, and the decoder uses the second key to re-encrypt
the decrypted control word and record the re-encrypted control word and the scrambled
digital data on a digital recording medium. The portable support device may be
used with any suitable decoder or digital recorder.