Information security device

An information security system in which content information and a usage rule of the content information are sent along a route from a first information security device to a second information security device, and then from the second information security device to a third information security device, and a rule change command of the usage rule is sent tracing the same route,

• wherein said second information security device includes:
• a receiving unit which receives, from said first information security device, the content information and a usage rule of the content information;
• a content information storage unit which stores the content information and the usage rule;
• a sending unit which sends, to said third information security device, the content information and the usage rule;
• a chain information generation unit which generates, as chain information of the content information, information including at least an identifier of the third information security device to which the content information is sent;
• a determination unit which determines whether or not the usage rule of the content information is permitted to be changed;
• a rule change command generation unit which generates the rule change command for instructing to change the usage rule of the content information, the rule change command being issued for the third information security device having the identifier indicated in the chain information, when said determination unit determines that the usage rule of the content information is permitted to be changed;
• and
• a control unit which changes the usage rule based on the rule change command,
• wherein said control unit deletes the content information stored in said content information storage unit, when said determination unit determines that the usage rule of the content information is permitted to be changed, and
• said sending unit sends the rule change command generated by said rule change command generation unit, to the third information security device having the identifier indicated in the chain information.

An information security method of receiving content information from a source device, using the content information, and sending the content information to a destination device, said information security method comprising:

• receiving, from the source device, the content information and a usage rule of the content information;
• storing the content information and the usage rule;
• sending, to the destination device, the content information and the usage rule;
• generating, as chain information of the content information, information including at least an identifier of the destination device to which the content information is sent;
• determining whether or not the usage rule of the content information is permitted to be changed;
• generating the rule change command for instructing to change the usage rule of the content information, the rule change command being issued for the destination device having the identifier indicated in the chain information, when it is determined in said determining that the usage rule of the content information is permitted to be changed;
• and
• controlling to change the usage rule based on the rule change command,
• wherein said controlling includes deleting the content information stored in said storing, when it is determined in said determining that the usage rule of the content information is permitted to be changed, and
• said sending includes sending the rule change command generated in said generating of the rule change command, to the destination device having the identifier indicated in the chain information.

A control program stored on a non-transitory computer-readable medium for an information security device which receives content information from a source device, uses the content information, and sends the content information to a destination device, said control program causing a computer to execute:

• receiving, from the source device, the content information and a usage rule of the content information;
• storing the content information and the usage rule;
• sending, to the destination device, the content information and the usage rule;
• generating, as chain information of the content information, information including at least an identifier of the destination device to which the content information is sent;
• determining whether or not the usage rule of the content information is permitted to be changed;
• generating the rule change command for instructing to change the usage rule of the content information, the rule change command being issued for the destination device having the identifier indicated in the chain information, when it is determined in said determining that the usage rule of the content information is permitted to be changed;
• and
• controlling to change the usage rule based on the rule change command,
• wherein said controlling includes deleting the content information stored in said storing, when it is determined in said determining that the usage rule of the content information is permitted to be changed, and
• said sending includes sending the rule change command generated in said generating of the rule change command, to the destination device having the identifier indicated in the chain information.

An integrated circuit configured for an information security device which receives content information from a source device, uses the content information, and sends the content information to a destination device, said integrated circuit comprising:

• a receiving unit which receives, from the source device, the content information and a usage rule of the content information;
• a content information storage unit which stores the content information and the usage rule;
• a sending unit which sends, to the destination device, the content information and the usage rule;
• a chain information generation unit which generates, as chain information of the content information, information including at least an identifier of the destination device to which the content information is sent;
• a determination unit which determines whether or not the usage rule of the content information is permitted to be changed;
• a rule change command generation unit which generates a rule change command for instructing to change the usage rule of the content information, the rule change command being issued for the destination device having the identifier indicated in the chain information, when said determination unit determines that the usage rule of the content information is permitted to be changed;
• and
• a control unit which changes the usage rule based on the rule change command,
• wherein said control unit deletes the content information stored in said content information storage unit, when said determination unit determines that the usage rule of the content information is permitted to be changed, and
• said sending unit sends the rule change command generated by said rule change command generation unit, to the destination device having the identifier indicated in the chain information.