Content providing system, content reproducing device, content reproducing method, and computer program

A content reproducing device for decrypting and outputting an encrypted content encrypted by a content key received from a content transmitting device, the content reproducing device comprising:

• circuitry that
• obtains the content key, the content key being encrypted with a first key unique to the content transmitting device and a second key unique to the content reproducing device, the first key being based on a unique identification number of the content transmitting device;
• stores the first key, usage restriction information to restrict usage of the first key, link information indicating linking of the content transmitting device and the content receiving device as being linked and owned by a same user, the link information including a path having an origin at the content transmitting device and a destination at the content reproducing device based on identification information of the content transmitting device and the content reproducing device, and hop count information indicating a number of generations the link information can be issued, each issuance of the link information being performed by a different content reproducing device;
• decrypts the content key with the first key in the event that the content reproducing device is included in the link information;
• restricts usage of the first key based on the usage restriction information;
• and
• when permitted by the usage restriction information, decrypts and reproduces the encrypted content using the content key, wherein
• a copyright management server configured to perform registration processing of a user and one or more content reproducing devices owned by one or more users, link the one or more users with the one or more content reproducing devices, and link the one or more content reproducing devices with one another, encrypt, and transmit the content key to the one or more content reproducing devices;
• the content transmitting device configured to distribute digital contents purchased by one of the one or more users via a network to one of the one or more content reproducing devices;
• and
• the one or more content reproducing devices owned by the one or more users, at least one of the one or more content reproducing devices coupled via the network with the copyright management server and the content transmitting device, the one or more content reproducing devices being linked together, the one or more content reproducing devices configured to reproduce the digital contents, the one or more content reproducing devices including at least a laptop, a boom box, a portable device with a headphone set, a set of portable audio players, and
• at least one or more content reproducing devices being commonly owned by more than one users, the digital contents purchased by a first user of the more than one users being allowed to be used by a second user, who does not purchase the digital contents, among the more than one users.

A content transmitting device for transmitting an encrypted content encrypted by a content key to a content reproducing device, the content transmitting device comprising:

• circuitry that:
• encrypts a first device key unique to the content transmitting device with a second device key unique to the content reproducing device, the first device key being based on a unique identification number of the content transmitting device;
• and
• provides the content reproducing device with link information for generating a path having an origin at the content transmitting device and a destination at the content reproducing device based on identification information of the content transmitting device and the content reproducing device, the first device key, the content key encrypted with the first device key, content usage restriction information, and hop count information indicating a number of generations the link information can be issued, the link information including an indication that the content transmitting device and the content reproducing device are linked and owned by a same user,
• wherein the content reproducing device uses the content usage restriction information to determine whether decryption of the encrypted content is permitted, and the content reproducing device decrypts and reproduces the encrypted content using the content key when permitted by the usage restriction information;
• a copyright management server configured to perform registration processing of a user and one or more content reproducing devices owned by one or more users, link the one or more users with the one or more content reproducing devices, and link the one or more content reproducing devices with one another, encrypt, and transmit the content key to the one or more content reproducing devices;
• the content transmitting device configured to distribute digital contents purchased by one of the one or more users via a network to one of the one or more content reproducing devices;
• and
• the one or more content reproducing devices owned by the one or more users, at least one of the one or more content reproducing devices coupled via the network with the copyright management server and the content transmitting device, the one or more content reproducing devices being linked together, the one or more content reproducing devices configured to reproduce the digital contents, the one or more content reproducing devices including at least a laptop, a boom box, a portable device with a headphone set, a set of portable audio players, and
• at least one or more content reproducing devices being commonly owned by more than one users, the digital contents purchased by a first user of the more than one users being allowed to be used by a second user, who does not purchase the digital contents, among the more than one users.

A content reproducing device for decrypting and outputting an encrypted content encrypted by a content key received from a content transmitting device, the content reproducing device comprising:

• circuitry that:
• obtains the content key encrypted with a first key unique to the content transmitting device and a second key unique to the content reproducing device, the first key being based on a unique identification number of the content transmitting device;
• stores the first key, usage restriction information to restrict usage of the first key, link information indicating linking of the content transmitting device and the content reproducing device as being linked and owned by a same user, the link information including a path having an origin at the content transmitting device and a destination at the content reproducing device based on identification information of the content transmitting device and the content reproducing device, and hop count information indicating a number of generations the link information can be issued;
• decrypts the content key with the first key in the event that the content reproducing device is included in the link information;
• restricts usage of the first key based on the usage restriction information;
• and
• when permitted by the usage restriction information, decrypts and reproduces the encrypted content using the content key, wherein
• a copyright management server configured to perform registration processing of a user and one or more content reproducing devices owned by one or more users, link the one or more users with the one or more content reproducing devices, and link the one or more content reproducing devices with one another, encrypt, and transmit the content key to the one or more content reproducing devices;
• the content transmitting device configured to distribute digital contents purchased by one of the one or more users via a network to one of the one or more content reproducing devices;
• and
• the one or more content reproducing devices owned by the one or more users, at least one of the one or more content reproducing devices coupled via the network with the copyright management server and the content transmitting device, the one or more content reproducing devices being linked together, the one or more content reproducing devices configured to reproduce the digital contents, the one or more content reproducing devices including at least a laptop, a boom box, a portable device with a headphone set, a set of portable audio players, and
• at least one or more content reproducing devices being commonly owned by more than one users, the digital contents purchased by a first user of the more than one users being allowed to be used by a second user, who does not purchase the digital contents, among the more than one users.

A content transmitting device for transmitting an encrypted content encrypted by a content key to a content reproducing device, the content transmitting device comprising:

• circuitry that:
• encrypts a first device key unique to the content transmitting device with a second device key unique to the content reproducing device, the first device key being based on a unique identification number of the content transmitting device;
• and
• provides the content reproducing device with link information for generation a path having an origin at the content transmitting device and a destination at the content reproducing device based on identification information of the content transmitting device and the content reproducing device, the first device key, content usage restriction information, and hop count information indicating a number of generations the link information can be issued, the link information including an indication that the content transmitting device and the content reproducing device are linked and owned by a same user,
• wherein the content reproducing device uses the content usage restriction information to determine whether decryption of the encrypted content is permitted, and the content reproducing device decrypts and reproduces the encrypted content using the content key when permitted by the usage restriction information;
• a copyright management server configured to perform registration processing of a user and one or more content reproducing devices owned by one or more users, link the one or more users with the one or more content reproducing devices, and link the one or more content reproducing devices with one another, encrypt, and transmit the content key to the one or more content reproducing devices;
• the content transmitting device configured to distribute digital contents purchased by one of the one or more users via a network to one of the one or more content reproducing devices;
• and
• the one or more content reproducing devices owned by the one or more users, at least one of the one or more content reproducing devices coupled via the network with the copyright management server and the content transmitting device, the one or more content reproducing devices being linked together, the one or more content reproducing devices configured to reproduce the digital contents, the one or more content reproducing devices including at least a laptop, a boom box, a portable device with a headphone set, a set of portable audio players, and
• at least one or more content reproducing devices being commonly owned by more than one users, the digital contents purchased by a first user of the more than one users being allowed to be used by a second user, who does not purchase the digital contents, among the more than one users.

A non-transitory computer-readable medium encoded with computer-readable instructions that, when executed by a computer, cause the computer to perform a method of decrypting and outputting encrypted content encrypted by a content key received from a content transmitting device, the method comprising:

• performing, by a copyright management server, registration processing of a user and one or more content reproducing devices owned by one or more users;
• linking the one or more users with the one or more content reproducing devices, and linking the one or more content reproducing devices with one another, encrypting, and transmitting the content key to the one or more content reproducing devices;
• distributing, by the content transmitting device, digital contents purchased by one of the one or more users via a network to one of the one or more content reproducing devices, wherein the one or more content reproducing devices owned by the one or more users, at least one of the one or more content reproducing devices being coupled via the network with the copyright management server and the content transmitting device, the one or more content reproducing devices being linked together, the one or more content reproducing devices reproducing the digital contents, the one or more content reproducing devices including at least a laptop, a boom box, a portable device with a headphone set, a set of portable audio players, at least one or more content reproducing devices being commonly owned by more than one users;
• allowing the digital contents, which is purchased by a first user of the more than one users, to be used by a second user, who does not purchase the digital contents, among the more than one users;
• obtaining the content key encrypted with a first key unique to the content transmitting device and a second key unique to a content reproducing device among the one or more content reproducing devices, the first key being based on a unique identification number of the content transmitting device;
• storing the first key, usage restriction information to restrict usage of the first key, link information indicating a linking of the content transmitting device and the content reproducing device as being linked and owned by a same user, the link information including a path having an origin at the content transmitting device and a destination at the content reproducing device based on identification information of the content transmitting device and the content reproducing device, and hop count information indicating a number of generations the link information can be issued;
• decrypting the content key with the first key when the content reproducing device is included in the link information;
• restricting usage of the first key based on the usage restriction information;
• and
• when permitted by the usage restriction information, decrypting and reproducing the encrypted content using the content key.

A non-transitory computer-readable encoded with computer-readable instructions thereon that, when executed by a computer, cause the computer to perform a method of transmitting an encrypted content encrypted by a content key to a content reproducing device, the method comprising:

• performing, by a copyright management server, registration processing of a user and one or more content reproducing devices owned by one or more users;
• linking the one or more users with the one or more content reproducing devices, and linking the one or more content reproducing devices with one another, encrypting, and transmitting the content key to the one or more content reproducing devices;
• distributing, by a content transmitting device, digital contents purchased by one of the one or more users via a network to one of the one or more content reproducing devices, wherein the one or more content reproducing devices owned by the one or more users, at least one of the one or more content reproducing devices being coupled via the network with the copyright management server and the content transmitting device, the one or more content reproducing devices being linked together, the one or more content reproducing devices reproducing the digital contents, the one or more content reproducing devices including at least a laptop, a boom box, a portable device with a headphone set, a set of portable audio players, at least one or more content reproducing devices being commonly owned by more than one users;
• allowing the digital contents, which is purchased by a first user of the more than one users, to be used by a second user, who does not purchase the digital contents, among the more than one users;
• encrypting a first device key unique to the content transmitting device with a second device key unique to a content reproducing device among the one or more content reproducing devices, the device first key being based on a unique identification number of the content transmitting device;
• and
• providing the content reproducing device with link information for generating a path having an origin at the content transmitting device and a destination at the content reproducing device based on identification information of the content transmitting device and the content reproducing device, the first device key, content usage restriction information, and hop count information indicating a number of generations the link information can be issued, the link information including an indication that the content transmitting device and the content reproducing device are linked and owned by a same user,
• wherein the content reproducing device uses the content usage restriction information to determine whether decryption of the encrypted content is permitted, and the content reproducing device decrypts and reproduces the encrypted content using the content key when permitted by the usage restriction information.

A method for decrypting and outputting an encrypted content encrypted by a content key received from a content transmitting device, the method comprising:

• performing, by a copyright management server, registration processing of a user and one or more content reproducing devices owned by one or more users;
• linking the one or more users with the one or more content reproducing devices, and linking the one or more content reproducing devices with one another, encrypting, and transmitting the content key to the one or more content reproducing devices;
• distributing, by a content transmitting device, digital contents purchased by one of the one or more users via a network to one of the one or more content reproducing devices, wherein the one or more content reproducing devices owned by the one or more users, at least one of the one or more content reproducing devices being coupled via the network with the copyright management server and the content transmitting device, the one or more content reproducing devices being linked together, the one or more content reproducing devices reproducing the digital contents, the one or more content reproducing devices including at least a laptop, a boom box, a portable device with a headphone set, a set of portable audio players, at least one or more content reproducing devices being commonly owned by more than one users;
• allowing the digital contents, which is purchased by a first user of the more than one users, to be used by a second user, who does not purchase the digital contents, among the more than one users;
• obtaining, with circuitry, the content key, the content key being encrypted with a first key unique to the content transmitting device and a second key unique to a content reproducing device among the one or more content reproducing devices, the first key being based on a unique identification number of the content transmitting device;
• storing, with the circuitry, the first key, usage restriction information to restrict the usage of the first key, link information indicating linking of the content transmitting device and the content reproducing device as being linked and owned by a same user, the link information including a path having an origin at the content transmitting device and a destination at the content reproducing device based on identification information of the content transmitting device and the content reproducing device, and hop count information indicating a number of generations the link information can be issued;
• decrypting, with the circuitry, the content key with the first key when the content reproducing device is included in the link information;
• restricting, with the circuitry, usage of the first key based on the usage restriction information;
• and
• when permitted by content usage restriction information, decrypting and reproducing the encrypted content using the content key.

A method for transmitting an encrypted content encrypted by a content key to a content reproducing device, the method comprising:

• performing, by a copyright management server, registration processing of a user and one or more content reproducing devices owned by one or more users;
• linking the one or more users with the one or more content reproducing devices, and linking the one or more content reproducing devices with one another, encrypting, and transmitting the content key to the one or more content reproducing devices;
• distributing, by a content transmitting device, digital contents purchased by one of the one or more users via a network to one of the one or more content reproducing devices, wherein the one or more content reproducing devices owned by the one or more users, at least one of the one or more content reproducing devices being coupled via the network with the copyright management server and the content transmitting device, the one or more content reproducing devices being linked together, the one or more content reproducing devices reproducing the digital contents, the one or more content reproducing devices including at least a laptop, a boom box, a portable device with a headphone set, a set of portable audio players, at least one or more content reproducing devices being commonly owned by more than one users;
• allowing the digital contents, which is purchased by a first user of the more than one users, to be used by a second user, who does not purchase the digital contents, among the more than one users;
• encrypting, with circuitry, a first device key unique to the content transmitting device with a second device key unique to a content reproducing device among the one or more content reproducing devices, the device first key being based on a unique identification number of the content transmitting device;
• and
• providing, with the circuitry, the content reproducing device with link information for generating a path having an origin at the content transmitting device and a destination at the content reproducing device based on identification information of the content transmitting device and the content reproducing device, the first device key, content usage restriction information, and hop count information indicating a number of generations the link information can be issued, the link information including an indication that the content transmitting device and the content reproducing device are linked and owned by a same user,
• wherein the content reproducing device uses the content usage restriction information to determine whether decryption of the encrypted content is permitted, and the content reproducing device decrypts and reproduces the encrypted content using the content key when permitted by the usage restriction information.