Terminal device, management server device, control method, and recording medium

A management server device to be used in a video recording and playback system,

• the video recording and playback system including:
• a cloud server device;
• a first video recording device that receives and encrypts a content that is distributed, and records the content encrypted, on the cloud server device via Internet;
• a terminal device that plays back the content;
• and
• the management server device that is connected to the first video recording device via Internet,
• the management server device comprising:
• a circuit;
• and
• a memory connected to the circuit, wherein
• the memory holds, in association with the cloud server device, first identification information for identifying the first video recording device, and
• the circuit,
• when the first video recording device is to be replaced with a second video recording device:
• replaces the first identification information held by the memory in association with the cloud server device, with second identification information for identifying the second video recording device;
• and
• transfers, to the second video recording device, protection information that is used for protecting the content and is held by the first video recording device.

A control method performed by a terminal device to be used in a video recording and playback system,

• the video recording and playback system including:
• a cloud server device;
• a video recording device that receives and encrypts a content that is distributed, and records the content encrypted, on the cloud server device via Internet;
• and
• the terminal device that plays back the content,
• the control method comprising:
• performing device authentication with the video recording device;
• obtaining a content key that is encrypted from the video recording device via the Internet;
• decrypting the content key using a common key shared between the video recording device and the terminal device;
• reading the content that is encrypted and recorded on the cloud server device, by accessing the cloud server device without passing through the video recording device;
• and
• decrypting the content read using the content key to play back the content.

A control method performed by a management server device to be used in a video recording and playback system,

• the video recording and playback system including:
• a cloud server device;
• a first video recording device that receives and encrypts a content that is distributed, and records the content encrypted, on the cloud server device via Internet;
• a terminal device that plays back the content;
• and
• the management server device that is connected to the first video recording device via Internet,
• the control method comprising:
• holding, in association with the cloud server device, first identification information for identifying the first video recording device;
• and
• when the first video recording device is to be replaced with a second video recording device:
• replacing the first identification information held by a memory in association with the cloud server device, with second identification information for identifying the second video recording device;
• and
• transferring, to the second video recording device, protection information that is used for protecting the content and is held by the first video recording device.

A non-transitory computer-readable recording medium having recorded thereon a program for a terminal device to be used in a video recording and playback system,

• the video recording and playback system including:
• a cloud server device;
• a video recording device that receives and encrypts a content that is distributed, and records the content encrypted, on the cloud server device via Internet;
• and
• the terminal device that plays back the content,
• the program causing a computer of the terminal device to execute:
• performing device authentication with the video recording device;
• obtaining a content key that is encrypted from the video recording device via the Internet;
• decrypting the content key using a common key shared between the video recording device and the terminal device;
• reading the content that is encrypted and recorded on the cloud server device, by accessing the cloud server device without passing through the video recording device;
• and
• decrypting the content read using the content key to play back the content.

A non-transitory computer-readable recording medium having recorded thereon a program for a management server device to be used in a video recording and playback system,

• the video recording and playback system including:
• a cloud server device;
• a first video recording device that receives and encrypts a content that is distributed, and records the content encrypted, on the cloud server device via Internet;
• a terminal device that plays back the content;
• and
• the management server device that is connected to the first video recording device via Internet,
• the program causing a computer of the management server device to execute:
• holding, in association with the cloud server device, first identification information for identifying the first video recording device;
• and
• when the first video recording device is to be replaced with a second video recording device:
• replacing the first identification information held by a memory in association with the cloud server device, with second identification information for identifying the second video recording device;
• and
• transferring, to the second video recording device, protection information that is used for protecting the content and is held by the first video recording device.

A terminal device to be used in a video recording and playback system,

• the video recording and playback system including:
• a cloud server device;
• a video recording device that receives and encrypts a content that is distributed, and records the content encrypted, on the cloud server device via Internet;
• and
• the terminal device that plays back the content,
• the terminal device comprising:
• a circuit;
• and
• a memory connected to the circuit, wherein
• using the memory, the circuit:
• performs device authentication with the video recording device;
• obtains a content key that is encrypted from a management server device via the Internet;
• decrypts the content key using a common key shared between the video recording device and the terminal device;
• reads the content that is encrypted and recorded on the cloud server device, by accessing the cloud server device without passing through the video recording device;
• and
• decrypts the content read using the content key to play back the content.