Unauthorized Device Detection Device And Unauthorized Device Detection System

Abstract

To provide an unauthorized device detection system capable of finding and specifying a device that was manufactured or altered unauthorizedly. A DVD player 400a writes its own device ID to a memory card 200a. When a user purchases content, a register device 300 reads a media ID and the device ID from the memory card 200a, and transmits the media ID and the device ID to a management server device 100. The management server device 100 calculates, based on pairs of media IDs and device IDs stored beforehand and the received pair of media ID and device ID, a total number of media IDs corresponding to the received device ID, and compares the calculated total number with a threshold value. If the total number exceeds the threshold value, the management server device 100 judges that the DVD player identified by the received device ID is an unauthorized device.

Description

TECHNICAL FIELD [0001] The present invention relates to unauthorized device detection techniques for finding or specifying an unauthorized device altered or manufactured by copying. BACKGROUND ART [0002] In recent years, the development of multimedia-related technologies, the emergence of large-capacity recording media, and the like have led to the advent of systems that distribute digital content (hereafter “content”) made up of video, audio, and the like on large-capacity recording media such as optical discs or via a network or broadcasting. [0003] In general, cryptography is employed to protect a copyright of content, that is, to protect content from unauthorized use such as unauthorized playback and copying. In detail, content encrypted using an encryption key is recorded on a recording medium such as an optical disc and distributed. Only a terminal in possession of a decryption key corresponding to the encryption key can decrypt the encrypted content read from the recording me...

AI Technical Summary

Benefits of technology

[0014] According to this configuration, a device that is likely to be an unauthorized device manufactured by copying can be detected based on the number of portable media used by unauthorized devices.

[0015] Here, the detection device may further include: a calculation unit that includes: an acquisition unit operable to acquire, from a rewritable portable medium used by the target device, a media identifier for identifying the portable medium and the device identifier held by the target device; a storage unit operable to store, in correspondence with a device identifier held by each past target device, one or more media identifiers respectively for identifying one or more rewritable portable media used by the past target device; and a calculating unit operable to calculate, using the stored device identifier and one or more media identifiers and the acquired device identifier and media identifier, a total number of media identifiers corresponding to a same device identifier as the acquired device identifier, as the total media number, and write the calculated total media number to the media number storage unit.

[0016] According to this configuration, the total media number can be calculated reliably.

[0017] Here, the comparison unit may further compare the total media number with a warning value that is smaller than the threshold value, wherein the identifier storage unit further stores the device identifier if the total media number is no greater than the threshold value but is greater than the warning value.

[0018] According to this configuration, a device that is likely to be either an unauthorized device or a device that requires a warning can be detected.

[0019] Here, the target device may be a playback device for decrypting encrypted content and playing back the decrypted content, wherein the detection device further includes: a prohibition unit operable to prohibit to output a decryption key used for decrypting the encrypted content to the portable medium, if the total media number is greater than the threshold value; and an output unit operable to output the decryption key to the portable medium, if the total media number is no greater than the threshold value.

Problems solved by technology

However, there is a danger that the decryption key may be revealed as a result of an unauthorized party conducting analysis inside the terminal.

However, neither patent document 1 nor patent document 2 discloses a method of specifying the key revealed to outside (i.e. the key to be invalidated).

This requires much labor and cost.

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