A playback method and a playback device for playing a system stream file are provided. The playback method uses the playback device having one or more memories and circuitry to play the system stream file. The playback method includes reading the system stream file and identifying whether the system stream file to be played back is a first system stream file having a first file format or a second system stream file having a second file format. If the system stream file to be played back is the first system stream file, the method further includes converting a file format of the system stream file that has been read out from the first file format into the second file format. The playback method further includes decoding the system stream file having the second file format.

A configuration capable of performing reliable source analysis of illegal copy content using content in which a reproduction path is settable is implemented. Content in which an individual segment region including a plurality of pieces of variation data which include different identification information embedded therein and are decryptable using different keys and a common segment region including single data are provided, and variation data is configured with an aligned unit is set. A content reproducing device calculates a reproduction path by applying a device key and selects and reproduces an aligned unit corresponding to the reproduction path on the basis of a variation data identifier recorded in an adaptation field in a plain text region at the head of a plurality of aligned units constituting the variation data.

A playback method using a playback device that plays a system stream file is provided. The playback device includes an individual decryption key that is owned individually by each of playback devices, and a common decryption key that is owned in common by a plurality of playback devices. The system stream file includes a first system stream file configured to be played back using both the individual decryption key and the common decryption key, and a second system stream file configured to be played back using only the common decryption key among the individual decryption key and the common decryption key. The method includes identifying whether the system stream file to be playback is the first system stream file or the second system stream file, in accordance with a file extension of the system stream file, and selecting a decryption process of the system stream file.

Content individualization, including: encrypting a first part of a source data set using a first key creating a first encrypted data set; encrypting a second part of the source data set using a second key creating a second encrypted data set; encrypting the second part of the source data set using a third key creating a third encrypted data set; and combining the first encrypted data set, the second encrypted data set, and the third encrypted data set to form a final encrypted data set. Key words include watermarking and content individualization.

A playback method using a playback device that plays a system stream file is provided. The playback device includes an individual decryption key that is owned individually by each of playback devices, and a common decryption key that is owned in common by a plurality of playback devices. The system stream file includes a first system stream file configured to be played back using both the individual decryption key and the common decryption key, and a second system stream file configured to be played back using only the common decryption key among the individual decryption key and the common decryption key. The method includes identifying whether the system stream file to be playback is the first system stream file or the second system stream file, in accordance with a file extension of the system stream file, and selecting a decryption process of the system stream file.

A memory storing AV data for playing back encrypted video on a playback device is provided. The AV data includes a system stream file including encrypted video information, and a management information file. The system stream file includes a first segment in which is repeated a first data unit that can be individually decrypted using a first decryption key, and has a second data unit of the same data size as the first data unit but cannot be decrypted by the first decryption key. The system stream file also includes a second segment which can all be decrypted using a second decryption key that the playback device has in common with another playback device. The management information file has a time map in which are correlated I-picture serving as random access point, and a presentation clock time of the I-picture. The I-picture is multiplexed in the second segment.

Content individualization, including: encrypting a first part of a source data set using a first key creating a first encrypted data set; encrypting a second part of the source data set using a second key creating a second encrypted data set; encrypting the second part of the source data set using a third key creating a third encrypted data set; and combining the first encrypted data set, the second encrypted data set, and the third encrypted data set to form a final encrypted data set. Key words include watermarking and content individualization.

A memory storing AV data for playing back encrypted video on a playback device is provided. The AV data includes a system stream file including encrypted video information, and a management information file. The system stream file includes a first segment in which is repeated a first data unit that can be individually decrypted using a first decryption key, and has a second data unit of the same data size as the first data unit but cannot be decrypted by the first decryption key. The system stream file also includes a second segment which can all be decrypted using a second decryption key that the playback device has in common with another playback device. The management information file has a time map in which are correlated I-picture serving as random access point, and a presentation clock time of the I-picture. The I-picture is multiplexed in the second segment.

In a playback method of a playback device that plays a system stream file including encrypted video information, the system stream file includes a first segment in which is repeated a first data unit that can be decrypted using a first decryption key that the playback device has and a second data unit of the same data size as the first data unit but cannot be decrypted by the first decryption key, and a second segment which can all be decrypted using a second decryption key that differs from the first decryption key. The playback method reads the system stream file, and performs conversion processing to convert the system stream file that has been read out into a post-conversion system stream, in which the second data unit in the first segment in the system stream file that has been read out is replaced with a plurality of continuous invalid packets, and outs the post-conversion system stream.

Provided is an information processing device including a data processing unit that executes reproduction processing of content recorded in an information recording medium. The content includes an individual segment region formed of a plurality of variation data in which identification information different from each other is embedded and each of which can be decrypted by a different key, and a common segment region formed of single data. The variation data is formed of a 6144 byte aligned unit. The data processing unit calculates a reproduction path by applying a device key held in a memory, and selects an aligned unit corresponding to one variation data that corresponds to the calculated reproduction path from a plurality of aligned units configuring the plurality of variation data in the individual segment region included in the data read from the information recording medium, and then, executes the decryption and reproduction processing.