Authentication and encryption utilizing command identifiers

A recording device, comprising:

• a data storage section operable to store content data that is transferable to an external apparatus;
• and
• an encryption processing section operable to execute encryption processing of transmission data with said external apparatus, said encryption processing section including a control section operable to receive a command identifier transferred from said external apparatus in accordance with a setting sequence, to retrieve a command from a register based on said command identifier, and to have said command executed, said control section further including a command number setting sequence in which numbers are sequentially incremented as said setting sequence;
• wherein, when said command identifier differs from said setting sequence, said control section is operable to (1) cancel processing of said command and (2) not accept command processing from any external apparatus during command execution relating to an encryption key exchange processing for encrypting data stored in a storage unit in said recording device, when said command processing is different from said pre-defined setting sequence.

A data processing method in a data processing system having a first apparatus and a second apparatus operable to transmit encryption data to each other, said method comprising:

• executing command processing control in said second apparatus for receiving a command identifier in accordance with a setting sequence, said command identifier being transferred from said first apparatus;
• retrieving, from a register, a command based on said command identifier;
• processing said command;
• and
• when said command identifier is different from said setting sequence, canceling said processing of said command and not accepting command processing from any external apparatus during command execution relating to an encryption key exchange processing for encrypting data stored in a storage unit in said recording device;
• wherein said setting sequence is a command number setting sequence in which numbers are sequentially incremented.

A non-transitory recording medium recorded with a computer program for executing data processing having certain actions in a data processing system that includes a first apparatus and a second apparatus operable to transmit encryption data to each other, said actions comprising:

• receiving a command identifier that is transferred from said first apparatus to said second apparatus in accordance with a setting sequence, said setting sequence being a command number setting sequence in which numbers are sequentially incremented;
• retrieving, from a register, a command based on said command identifier;
• processing said command;
• and
• when said command identifier is different from said setting sequence, canceling said processing of said command and not accepting command processing from any external apparatus during command execution relating to an encryption key exchange processing for encrypting data stored in a storage unit in said recording device.