Content Protection scheme for a digital recording device

A method of recording digital data, comprising:

• receiving packets of a digital data stream in a recording and playback device;
• encrypting the received packets in the recording and playback device according to an encryption key unique to the recording and playback device;
• storing the encrypted packets, wherein
• a packet comprises a first predetermined number of header bytes and a second predetermined number of payload bytes;
• the header bytes are stored unencrypted;
• and
• the payload bytes are stored encrypted,
• whereby operations performable on the data stream that require access to header bytes but not to payload bytes are performable on the stored encrypted packets of the data stream, wherein
• stored packets are retrieved, header bytes are replaced, and payload bytes are decrypted;
• the recording and playback device includes a random-access memory having a plurality of byte locations each corresponding to a different one of a plurality of first memory addresses;
• bytes constituting a packet of the decrypted data stream appear sequentially at the output of a FIFO memory;
• the output of the FIFO memory is mapped to a number of second memory addresses at least equal to the number of bytes comprising a packet;
• the second memory addresses are contiguous with the first memory addresses;
• the replacement header bytes are loaded into the n highest locations of the random-access memory, where n is the first predetermined number;
• readout of the packet is accomplished by reading a number of the memory addresses equal to the sum of the first and second predetermined numbers commencing from the random-access memory address where the replacement header bytes commence.

Apparatus for recording and playing back digital data, comprising:

• a data receiver for receiving packets of a digital data stream;
• an encrypter for encrypting the received packets according to an encryption key unique to the apparatus;
• a data store for storing the encrypted packets;
• and
• a readout path for retrieving at least a portion of the encryption key and arranged to be disabled by a first irrevocable condition and to be re-enabled by a second irrevocable condition, said readout path being connectable to an external IC tester and wherein recording and playback functioning of the apparatus is disabled by said second irrevocable condition.

Apparatus for recording and playing back digital data, comprising:

• a data receiver for receiving packets of a digital data stream;
• an encrypter for encrypting the received packets according to an encryption key unique to the apparatus;
• a data store for storing the encrypted packets, wherein a packet comprises a first predetermined number of header bytes and a second predetermined number of payload bytes, the data store stores the header bytes unencrypted, and the data store stores the payload bytes encrypted, whereby operations performable on the data stream that require access to header bytes but not to payload bytes are performable on the recorded data stream,
• wherein stored packets are retrieved from the data store, control logic replaces header bytes, and payload bytes are decrypted,
• a random-access memory having a plurality of byte locations each corresponding to a different one of a plurality of first memory addresses;
• and
• a FIFO memory sequentially outputting bytes constituting a packet of the decrypted data stream, wherein:
• the output of the FIFO memory is mapped to a number of second memory addresses at least equal to the number of bytes comprising a packet;
• and
• the second memory addresses are contiguous with the first memory addresses, and wherein:
• the control logic loads replacement header bytes into the n highest locations of the random-access memory, where n is the first predetermined number;
• and
• the control logic reads out the packet by reading a number of the memory addresses equal to the sum of the first and second predetermined numbers commencing from the random-access memory address where the replacement header bytes commence.

A recorder for recording digital data streams, comprising:

• hardware dimensioned and arranged for encrypting packets of a digital data stream according to a binary key at least a portion of which is stored in said hardware of the recorder;
• a readout path for retrieving said key portion stored in said hardware of the recorder, said readout path arranged to be disabled by a first irrevocable condition and re-enabled by a second irrevocable condition, said readout path being connectable to an external IC tester;
• and
• at least one feature essential for recording and playback functioning of the recorder arranged to be disabled by said second irrevocable condition.

A method practiced in a recorder for recording digital data streams, comprising the steps of:

• encrypting, according to a binary key at least a portion of which is stored in hardware of the recorder, packets of a digital data stream, the recorder including a readout path for retrieving said key portion, the readout path being connectable to an external IC tester;
• arranging said readout path to be disabled by a first irrevocable condition and re-enabled by a second irrevocable condition;
• and
• arranging at least one feature essential for recording and playback functioning of the recorder to be disabled by said second irrevocable condition.

A set-top box for recording and playing back digital data, consisting of a housing which comprises:

• a data receiver for receiving packets of a digital data stream;
• an encrypter for encrypting the received packets according to an encryption key unique to the set-top box;
• a data store for storing the encrypted packets;
• and
• a readout path for retrieving at least a portion of the encryption key and arranged to be disabled by a first irrevocable condition and to be re-enabled by a second irrevocable condition said readout path being connectable to an external IC tester and wherein recording and playback functioning of the apparatus is disabled by said second irrevocable condition.