JP2000231758A - Data storage device, recording method of ciphered data and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a storage system in which a reproducing control for ciphered digital contents is efficiently conducted even though digital contents are ciphered and recorded as they are. SOLUTION: When a digital versatile disk(DVD)-RAM drive 116 receives 1394 packets from a set top box(STB) 12, the drive 116 takes out ciphered MPEG2-TS packets. A reproducing control information adding section 1162 adds a time stamp (time information) for a special reproducing to the ciphered MPEG2-TS packets as reproducing control information. A time varying information control section 1163 adds time varying element information to specify the time variable used to cipher the data to be ciphered in one sector unit, for example. Thus, one sector data recorded in a DVD-RAM medium are constituted of time varying element information (a difference of Nc), a time stamp and a ciphered MPEG2-TS packet group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data storage device, a method for recording encrypted data, and a recording medium used in a digital content copy protection system.

[0002]

2. Description of the Related Art In recent years, with the development of computer technology,
Digital video player, set-top box, T
A variety of multimedia-compatible electronic devices such as V, digital VCR, and personal computer have been developed. This type of electronic device is, for example, a DVD (Digital Ve
(satellite Disk), and digital contents such as TV programs by digital satellite broadcasting. These digital contents are generally encoded using a moving picture high-efficiency encoding method called MPEG2, and then sent to each home through a recording medium or a transmission medium.

[0003] In recent years, from the viewpoint of copyright protection of such digital contents, the necessity of a copy protection technique for preventing unauthorized copying has been called out. Therefore, recently, a new copy protection method for an IEEE 1394 serial bus, which is a next-generation bus interface suitable for multimedia data transmission, is being studied.

[0004]

As the IEEE 1394 copy protection technology, digital contents are encrypted by using a well-known encryption protocol such as a public key encryption system or a common key encryption system, and the encrypted content is encrypted. A mechanism has been considered in which digital contents are transferred between devices such as a digital video player, a set-top box, a TV, a digital VCR, and a personal computer via an IEEE 1394 serial bus. In this case, the content is encrypted by the transmitting device and transmitted to the receiving device, and the receiving device decrypts the encrypted data.

However, for example, when a content such as a digital broadcast program is recorded on a digital VCR or DVD-RAM, a digital VCR or DVD on the receiving side is considered.
If the encryption is decrypted in the RAM, the raw data will be digitally recorded, and the risk of unauthorized copying will increase. Therefore, as described in Japanese Patent Application No. 10-108118, which is a patent application filed by the present applicant, digital contents to be transmitted in an encrypted form are encrypted with a digital VCR or DVD-RAM.
It is preferable to digitally record the data. In addition, Japanese Patent Application Hei 10
In the specification of -108118, a key for decrypting encrypted digital content is recorded in an area that cannot be read from the system, thereby concealing the key.

[0006] Generally, various reproduction controls of digital contents recorded on a recording medium are performed by referring to reproduction management information such as an address and time included in the source data itself of the digital contents. Specifically, in the case of a DVD video title recorded on a DVD medium, only the target video data portion is read out from the DVD medium by referring to the address of the video object included in the source data. Special playback such as fast-forward playback, fast-forward reverse playback, and multi-scene playback was realized.

However, as described above, when the entire source data of digital content is digitally recorded while being encrypted for the purpose of copy protection, the content of the source data cannot be referred to. Therefore, since it is not possible to control to read only the data portion necessary for reproduction, the entire encrypted source data, including data not used for reproduction, must always be sequentially read from the recording medium. Useless data transfer occurs with the reproducing apparatus. Also,
In this case, it is necessary to prepare a large-capacity reception buffer on the reproduction device side, which leads to an increase in the cost of the reproduction device.

In a copy protection system using a time-varying element value as an encryption key, the encryption key required for decryption of the same content changes with time. Therefore, when digital data is recorded while the source data of the digital content is encrypted, it is necessary to notify the playback device of a time-varying element value corresponding to the encrypted data portion to be played back.

However, as described above, in order to keep the encryption key information confidential, in the method of recording the encryption key information and the encrypted data in separate areas, the encrypted data portion to be reproduced and the corresponding encrypted data portion are stored. Cannot be read at the same time. Therefore, every time the encrypted data portion to be reproduced is switched, the corresponding encryption key information must be read from another area. Therefore, it is practically difficult to perform decryption / reproduction in real time while confirming a change in the encryption key on the reproduction device side.

[0010] The present invention has been made in view of the above-mentioned circumstances, and a data storage device and a recording method of encrypted data capable of efficiently controlling the reproduction even when digital content is recorded while being encrypted. And a recording medium.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problem, the present invention provides a method of recording data on a recording medium while encrypting copy-protected data, which is transmitted from a destination device after being encrypted. A recording device, comprising: a receiving unit that receives the encrypted data; and a plurality of encrypted data units that form the encrypted data received by the receiving unit. Recording means for adding to the recording medium the reproduction management information indicating the general order relationship.

In this data recording device, reproduction management information is added to each encrypted data unit and digitally recorded. Therefore, by referring to the reproduction management information, an arbitrary part of the encrypted data can be set in the middle of the encrypted data. The part can be read and reproduced. Therefore, even during special playback such as fast-forward playback, fast-forward reverse playback, and multi-scene playback, without reading out all the encrypted data, only the encrypted data portion necessary for the special playback is read out from the recording medium and sent to the playback device side. It becomes possible to transmit.

In addition, the encrypted data is divided into a plurality of packets each having a time stamp composed of predetermined time information for compensating for a transmission delay difference such as a packet transmission time. In a system transmitted from the destination device, the recording unit can use a time stamp added to the packet received by the receiving unit as the reproduction management information. This makes it possible to omit the process of generating the dedicated reproduction management information.

In the case where an encryption key including a time variable as an encryption key generation element is used for encrypting the data to be copy protected, the recording means stores the encrypted data in each of the encrypted data units. Further comprising time-varying element information adding means for adding time-varying element information for specifying the value of the time variable used for the encryption, wherein the encrypted data unit includes the reproduction management information and the time-varying element. The information is recorded on the recording medium in a state where the information is added.

As described above, since the encrypted data unit and the time-varying element information corresponding thereto are packetized and recorded, even in a copy protection system using the time-varying element value as an encryption key, the encrypted data unit can be used. And the time-varying element information necessary for the decoding thereof can be simultaneously read and transmitted to the reproducing apparatus.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a copy protection system according to an embodiment of the present invention. In this example, a personal computer (hereinafter, referred to as a PC)
An example of a system for recording digital content in a DVD-RAM drive used as a peripheral device while encrypting the content in an encrypted manner will be described.

The PC 11 is connected to an external consumer electronic device, for example, a set-top box (STB) 1 as shown in FIG.
2. Digital video camera or DV camcorder (DV
C) 13 and a digital video cassette recorder (D
-VCR) 14.

A set-top box (STB) 12, a digital video camera (DVC) 13, and a digital video cassette recorder (D-VCR) 14 provide device authentication, key exchange, and the like to an interface with the IEEE 1394 serial bus 200, respectively. Authentication processing units (Authenticators) 121 and 13 to be performed
1,141. For a set-top box (STB) 12 and a digital video cassette recorder (D-VCR) 14 for transmitting and receiving digital contents, an encryption / decryption unit (De- / Cipher) 122 having both encryption and decryption functions. , 142 are provided. The digital video camera (DVC) 13 that only transmits digital contents is provided with only an encryption unit (Cipher) 132.

PC 11, set-top box (ST
B) 12, a digital video camera (DVC) 13, and a digital video cassette recorder (D-VCR) 14
Digital contents exchanged between them are transferred on the IEEE 1394 serial bus 200 in an encrypted state.

The PC 11 is connected to the PCI bus 1 as shown in FIG.
00 and a plurality of functional modules connected thereto. Among these functional modules, functional modules for handling digital contents, that is, a CPU module 111, a tuner 113 for satellite or digital TV, an MPEG2 decoder 115, a DVD-R
As for the AM drive 116, an authentication processing unit (Authenticator) 111 for performing device authentication and key exchange is provided in an interface unit with the PCI bus 100.
1, 1131, 1151, 1161 are provided.
Each of these authentication processing units (Authenticator) 1
Basically, the functions of 111, 1131, 1151, and 1161 are basically the same as the set-top box (STB) 12 and the digital video camera (DVC) 1 which are 1394 devices.
3, and a digital video cassette recorder (D-VC
R) It is the same as that of 14, and performs authentication and key exchange necessary for encrypting and transmitting digital contents.

Authentication processing unit (Authenticato)
r) In 1111, 1131, 1151, 1161,
Authentication information (authentication format) for each corresponding functional module is held. This authentication format is used to certify the validity of the function module to the function module or the external device of the other party that exchanges the data to be copy protected, and is a kind of electronic signature. By exchanging the authentication format of each device with the authentication partner,
It becomes possible to perform authentication processing for each functional module for confirming whether or not the device is a valid device that can mutually handle copy-protected data.

The authentication format includes information for specifying the validity of the corresponding function module and the type of data that can be handled (copy impossible, copy once only, copy free). The authentication format is embedded in a circuit or firmware of each function module in the PC 11, or a device driver corresponding to the function module.

Also, a set-top box (STB) 1
2. Authentication processing units (Authenticators) 121 and 13 of digital video camera (DVC) 13 and digital video cassette recorder (D-VCR) 14
1 and 141 also hold the authentication format of the corresponding device.

CPU module 111, tuner 11
3. In the interface section of the MPEG2 decoder 115, the encrypted content (encrypt
A decryption unit (De-cipher) or an encryption unit (Cipher) that performs decryption processing for decrypting the encryption of the content (contents) is provided. Whether to have an encryption unit, a decryption unit, or both depends on the function of each functional module. here,
The encryption unit (Cipher) 1 for the tuner 113
132, the CPU module 111 and the MP
For the EG2 decoder 115, the decoding unit (De-ci
pher) 1112 and 1152 are illustrated.

The CPU module 111 includes a microprocessor, a memory controller, a PCI bus bridge, and the like. The authentication unit 1111 and the decryption unit 1112 can be incorporated as a part of the PCI bus bridge, for example. Also, the CPU module 111
Authentication unit 1111, decryption unit 1112, MPEG2
The decoder unit 1113 may be realized by software.

The DVD-RAM drive 116 is a PC 11
And is connected to the PCI bus 100 via an IDE interface or an ATAPI interface or the like. DVD-RAM
The drive 116 has only an authentication processing unit 1161, and includes a decryption unit (De-cipher) and an encryption unit (Ciphe).
r) is not provided. This is because the encrypted digital content that can be copied only once is recorded on the DVD-RAM 116 in an encrypted state.

The DVD-RAM drive 116 has a reproduction management information adding section 1162 and a time-varying information management section 116.
3 are provided. The reproduction management information adding unit 1162
Playback management information such as time information necessary for special playback is added to the encrypted data to be recorded. As a result, the encrypted data is recorded in the data area on the DVD-RAM medium in a state in which raw reproduction management information that is not encrypted is added in units of an encrypted data unit having a predetermined size constituting the encrypted data. In this case, each piece of reproduction management information indicates a temporal order relationship between the corresponding encrypted data unit and another encrypted data unit. Therefore, by referring to the reproduction management information, it is possible to read and reproduce an arbitrary portion from the middle of the encrypted data, and to read all the encrypted data even during special reproduction such as fast-forward reproduction or multi-scene reproduction. Instead, only the encrypted data portion necessary for the special reproduction can be read from the DVD-RAM medium and transmitted to the reproduction device.

The time-varying information management unit 1163 adds time-varying element information for specifying the value of the time variable used for the encryption for each encrypted data unit. In this way, each encrypted data unit and its corresponding time-varying element information are packeted together and recorded in the data area on the DVD-RAM medium, so that the encrypted data unit and its The variable element information can be read out at the same time and transmitted to the reproducing apparatus.

The PC 11 further includes a PCI bus 100
And a IEEE1394 serial bus 200 are provided with a 1394 bridge 117 for bidirectional connection. 13
The 94 bridge 117 is not provided with any of an authentication processing unit, an encryption unit, and a decryption unit, and the encrypted digital content is kept in the PCI bus 100 in an encrypted state.
From the IEEE 1394 serial bus 200 to the IEEE 1394 serial bus
EE1394 serial bus 200 to PCI bus 100
Transferred to Thus, the 1394 bridge 117
Connects transparently between the function module in the PC 11 and the 1394 device.

Here, a description will be given of a processing procedure when digital contents such as a TV program by digital satellite broadcasting are fetched from the STB 12 to the PC 11 via the IEEE 1394 serial bus 200 and recorded on the DVD-RAM drive 116.

First, under the control of the CPU 111, STB1
2 and the DVD-RAM drive 116 perform device authentication and mutually confirm that they are valid devices having a copy protection function. This authentication processing is realized by using a well-known method such as a random challenge and response method, a method using a one-way function, a method using a time variable that changes every time, or a combination of these methods. In the authentication process, the authentication formats are exchanged with each other, and it is confirmed that the devices can handle what kind of data (copy impossible, copy once, copy free). This authentication process has two levels: full authentication and restricted authentication.
The authentication level is determined depending on what kind of data the devices of the authentication partners can handle.

Further, in this authentication processing, the DV
The D-RAM drive 116 exchanges a key with the STB 12 under the control of the CPU 111, and generates encryption key information necessary to generate a key (content key) for decrypting the encrypted content. To get.

STB 12 and DVD-RAM drive 11
If the STB 12 is authenticated as a valid device having a copy protection function with the STB 6, the STB 12 encrypts the digital content and sends it to the DVD-RAM drive 116. The encrypted content remains encrypted while the 1394 bus 200 and the PCI bus 100
Arrives at the DVD-RAM drive 116 via the
-It is recorded on the DVD-RAM medium of the RAM drive 116 while being encrypted. At the time of recording the encrypted data, as described above, the reproduction management information and the time-varying element information are added for each predetermined encrypted data to be recorded.

As described above, the authentication processing section is prepared in the interface section of each of a plurality of functional modules for handling digital contents, and when copy-protected digital contents are transferred between functional modules or between a functional module and an external 1394 device. In addition, by performing authentication processing and digital content encryption / decryption processing between these devices, a key for decryption and digital content are encrypted in both the IEEE 1394 bus 200 and the PCI bus 100. The digital content is transferred as it is, and illegal copying of digital content can be prevented. The authentication processing unit of each functional module can be realized by a device driver corresponding to the functional module, hardware of the functional module, or firmware for controlling the hardware.

Further, since the authentication process with the partner device is performed for each functional module in the PC 11 using the corresponding authentication format, for example, the MPE
The G2 decoder 115 can handle all types of content (copy once, copy impossible, copy free), and the DVD-RAM drive 116 can handle only copy-only content and copy-free content. In this way, it is possible to limit the types of digital contents (copy permitted only once, copy prohibited, copy free) that can be individually handled for each functional module in the same PC.

FIG. 2 shows the relationship between software and hardware in the system of FIG.

In FIG. 2, the upper side of the dashed line is software, and the lower side is hardware. Blocks with thick frames, which are hierarchically arranged in the vertical direction, are hardware modules such as functional modules in the PC 11 or 1394 devices.

The Authenticator handler is:
In response to a request from an application program such as digital content reproduction software, control for authentication processing and key exchange with necessary hardware devices is performed. That is, under the control of the Authenticator handler, authentication information is exchanged between the function modules or between the function module and the external device, whereby a valid device capable of handling data to be copy-protected. An authentication process for confirming whether or not the authentication is performed is performed.

As described above, the 1394 bridge 117
Implements the same authentication and encryption / decryption protocol as the 1394 device in each function module in the PC 11 because the function module in the PC 11 is transparently connected to the 1394 device. As shown, from the application program PC11
It is possible to treat each functional module and the 1394 device equally without distinguishing them.

FIG. 3 shows an example of the procedure of the authentication processing and the encryption processing used in the present embodiment. The device that sends the content is the source device
e (sending node), the receiving device is Sink
Device (receiving node).

The sink device first passes an authentication request to the source device. The authentication request includes information such as an authentication format of the sink device. Source Device
Verifies whether the sink device is a device having a legitimate copy protection function that can handle the content to be transmitted (copy impossible, copy once, copy free). Source Dev
ice confirms that the Sink Device is a valid device, and sends a response to the authentication request to the Sin Device.
Return to k Device. This response includes the Sour
Information such as the authentication format of ce Device,
CGM indicating whether the digital content to be sent is copy-inhibited, copy-once only, or copy-free
Copy control information (EMI) called S is included. The content of the copy control information (EMI) is represented by a predetermined function (f [EMI]), which is sent to the sink device.

Sink Device is Source
The Sou using the device authentication format
It verifies whether the rc device is a device having a valid copy protection function. After confirming that the other device is a legitimate device,
This time, Sink Device and Source De
same authentication key (Kauth)
A key exchange process for sharing the key is performed.

Next, Source Device is:
A control key (Kx) is generated using a random number, and the control key Kx encrypted with an authentication key (Kauth) (e [Kx]) is transmitted to the sink device. Sink Device converts the encrypted control key (e [Kx]) into an authentication key (Kout).
h) to generate a control key Kx. After that, the SourceDevice generates a time variable Nc whose contents sequentially change depending on the time and the like,
Send to the ink device. Source De
Vice generates a content key (Kc), which is an encryption key for encrypting the content, from three elements of Kx, f [EMI], and Nc.

Kc = j [Kx, f [EMI], Nc] Incidentally, although details will be described later, actually, Kx and f [EM]
I] is used as one element, and a content key (Kc) is generated by Kc = j [Kx + f [EMI], Nc].

Then, the Source Device is
The digital content is encrypted using the content key (Kc), and the encrypted data is transmitted to the sink device in the form of 1394 packet data. Sink D
Since the device already has the three elements Kx, f [EMI], and Nc, the content key (Kc) can be generated. The sink device decrypts the encrypted data using the generated content key (Kc).

The source device updates the value of Nc every time a predetermined time elapses, and Kc + 1 = j [Kx,
f [EMI], Nc + 1], specifically, Kc + 1 = j [Kx + f [EMI], Nc + 1] is used as a new content key (Kc). Then, the encrypted data encrypted by Kc + 1 is transmitted. N
The update of the value of c is notified to the sink device by control information (Odd / Even bit) included in the 1394 packet header. Sink
Device generates Kc + 1 and generates the generated Kc
The encrypted data is decrypted by +1.

Thereafter, while updating the value of Nc in this manner, digital content encryption, transmission and decryption of encrypted data, and the like are repeatedly performed. DVD-RAM
If the drive 116 is a sink device,
The decryption of the encrypted data is not performed, and the digital content is recorded on the DVD-RAM medium while being encrypted.

Next, referring to FIG. 4, digital content that can be copied only once, such as a digital satellite broadcast program received by STB 12, is encrypted to form a DVD-RA.
A processing procedure for recording on the M drive 116 will be described.

The DVD-RAM drive 116 is actually a PCI bus, 1394 bridge 117, IEEE
Although connected to the STB 12 via the 1394 bus,
IEEE 1394 bus 20 by 94 bridge 117
0 and the PCI bus 100 are transparently connected to each other, so that the digital-content transfer process from the STB 12 to the DVD-RAM drive 116 and vice versa can be performed by the DVD-RAM drive 116 as shown in FIG. It can be treated equivalently to the case where it is connected to the STB 12 via the bus 200. Also, of course, the DVD-RAM drive 116 itself has IEEE13
Provide an interface with the 94 bus 200,
The RAM drive 116 is connected to the IEEE 1394 bus 200
May be directly connected.

(1) Authentication section (Authenticato) of each of STB 12 and DVD-RAM drive 116
r) The three elements (Kx, f [EMI], Nc) for generating the content key (Kc) by the authentication and key exchange processing by 122 and 1161
Shared with the VD-RAM drive 116. The authentication process between the STB 12 and the DVD-RAM drive 116 is performed under the control of the CPU 111.

(2) In the DVD-RAM drive 116, Kx, f [EMI] and Nc are gap areas (sector headers) between sectors on the DVD-RAM which cannot be referred to from a normal file system such as an operating system. Will be recorded. Here, actually, the content of f [EMI] recorded in the gap area is changed from a value indicating "copying is allowed only once" to a value indicating "copying is not possible any more".

(3) Digital contents such as digital satellite broadcast programs received by the STB 12 are compression-encoded by MPEG2. This compression-encoded digital content is composed of 188-byte MPEG2 transport stream packets (MPEG2_TS packets). The STB 12 encrypts the MPEG2_TS packet with the content key (Kc), and
It mounts on a 394 packet and sends it.

(4) The DVD-RAM drive 116
When a 1394 packet is received, an encrypted MPEG2_TS packet is extracted therefrom. The reproduction management information adding unit 1162 adds a time stamp (time information) for special reproduction to the encrypted MPEG2_TS packet as reproduction management information. The time stamp is added in, for example, a data size unit for one sector. The time stamp of each sector indicates a temporal order relationship among the plurality of sector data. As the time stamp, for example, time information indicating the arrival time of the 1394 packet is generated by the reproduction management information adding unit 1162 and used, or the transmission time is indicated in advance in the 1394 packet transmitted from the STB 12. When the time stamp is added as the source packet header, the time stamp given by the source packet header can be used as it is as the time stamp for the reproduction management information.

(5) The time-varying information management unit 1163 adds time-varying element information for specifying a time variable used for encrypting the encrypted data, for example, in units of one sector. Here, since the value Nc of the first time variable is already recorded in the cap area (sector header) between the sectors, the time-varying element information added to the sector data is N
The difference of c can be used. For example, when the value of the time variable is changed to Nc + 1, the difference of Nc to be added to the sector data is “+1”.

Thus, one sector data recorded on the DVD-RAM medium is composed of time-varying element information (Nc difference), a time stamp, and a group of encrypted MPEG2_TS packets, as shown in the figure. become.

(6) A digital content recorded in an encrypted form on a DVD-RAM medium is, for example, M
MPEG2 with built-in PEG2 decoder 115 and STB12
When the content is reproduced by a decoder or the like, the same content key Kc used when recording the digital content on the DVD-RAM medium is obtained by performing authentication and key exchange processing between the DVD-RAM drive 116 and the reproducing device. The content key Kc is generated on the playback device side. The generation of the content key Kc is based on Kx, f [EMI], Nc recorded in the gap area of the DVD-RAM medium.
It is performed based on. However, since the content of f [EMI] of the DVD-RAM medium has already been changed from the value indicating "copy once only" to the value indicating "no more copy" as described above, the same content key is used. To enable Kc to be generated on the playback device side, f [EM
It is necessary that the playback device be able to generate a new control key Kx ′ that cancels out the change in I]. Therefore, the DVD-RAM drive 116
Generates a new control key Kx ′ based on the previous Kx recorded in the gap area of the DVD-RAM medium, instead of generating the control key Kx ′ using a random number. Specifically, Kx 'is generated such that Kx + f [copy is allowed only once] = Kx' + f [copy is no longer possible].

Thus, Kc = j [Kx + f [EM
If the content key is generated using the function of [I], Nc], it becomes possible to generate the same content key Kc as the content key Kc used when recording the digital content on the DVD-RAM medium.

The reproduction management information adding section 1162 and the time-varying information management section 1163 are provided in the DVD-RAM drive 1
16, DVD-RAM drive 116
Device driver for controlling
It can be realized by firmware for controlling the microcomputer in the RAM drive 116 or the like.

Next, a specific data format (recording format) for recording digital content on a DVD-RAM medium will be described with reference to FIG.

As described above, in the gap area between the sectors on the DVD-RAM medium, Kx, f [EM
I] and Nc are recorded. In this case, the content of f [EMI] is changed from “copying only once” to “copying no more”.
It is recorded in the state changed to the state.

The data size of one sector of the DVD-RAM medium is 2 Kbytes. As shown in FIG. 5 (A), time-varying element information (difference in Nc) is located at the head of the 2 Kbyte sector data, and a time stamp (reproduction management information) is located thereafter. . After the time stamp, 188 bytes of encrypted MPEG2
_TS packet group follows. Thus, DVD-RA
By adding and recording a time stamp for each sector which is an access unit of the M media, it is possible to efficiently read only the data to be reproduced with reference to the time stamp. For example, in the case of fast forward playback,
Sectors having time stamps at predetermined time intervals are sequentially selected, and encrypted MPs are selected from within each of the selected sectors.
The EG2_TS packet is read.

Further, since the time-varying element information (difference of Nc) is added to each sector data, the encrypted MPE
While reading out the G2_TS packet, it is possible to notify the content of Nc necessary for decryption to the reproducing apparatus side.

FIG. 5B is a diagram showing the state of the 1 received from the STB 12.
This is a format of sector data when a time stamp given by a source packet header added to a 394 packet is used as it is as a time stamp for reproduction management information. In this case, the time-varying element information (difference of Nc) is located at the head of the 2K-byte sector data, followed by a 4-byte source packet header (SPH) and a 188-byte encrypted MPEG2_
A set with a TS packet follows. That is, in the 1394 packet including the source packet header, 13
The payload part of the 94 packet has a 4-byte source packet header (SPH) and an 188-byte encrypted M
It is composed of a total of 192 bytes of data with the PEG2_TS packet, and the 192-byte 1394 packet payload group is directly followed by the time-varying element information (difference of Nc).

Here, the structure of the 1394 packet transmitted from the STB 12 will be specifically described with reference to FIG.

STB 12 is the MPEG2_T to be transmitted.
The S packet is mounted on a 1394 packet for isochronous transfer. As described above, the MPEG2_TS packet is a fixed-length packet of 188 bytes, in which a bit stream of moving image data and a bit stream of audio data are multiplexed. The STB 12 uses this MP
A 4-byte source packet header (SPH) defined by IEC61883 is added to the EG2_TS packet. The source packet header (SPH) is 139
This is a time stamp added to solve the problem caused by the transmission delay difference between the four packets, and is composed of predetermined time information for compensating for the transmission delay difference.
Usually, the packet transmission time by the transmitting node is added as a source packet header. By adding the source packet header and transmitting, even if the arrival order of the packets is shifted, the packets can be rearranged in the correct order on the receiving side. Further, the packet restoration time on the receiving side can be designated by the time stamp given in the source packet header. That is, the time stamp including the packet transmission time and the like is used as time information for specifying the packet restoration time. In this case, the receiving side buffers the received packet and restores it according to the time stamp given in the source packet header, so that even if a different transmission delay occurs for each packet, video and audio etc. Digital content can be decrypted and reproduced.

The STB 12 generates a 1394 packet by adding a 1394 packet header for isochronous transfer to the beginning of 192 bytes of data composed of a source packet header (SPH) and an MPEG2_TS packet. The 1394 packet header contains N
An Odd / Even bit indicating whether or not c has changed is also included. The generated 1394 packet is 125 μs
Is transferred at one rate in the isochronous cycle.

As described above, the encrypted digital content is transmitted from the STB 12 after being divided into a plurality of 1394 packets each having a time stamp indicating the packet transmission time and the like added thereto. As described above, by using the time stamp as it is as the time stamp for the reproduction management information, the DVD-RA
The processing of generating a dedicated time stamp based on the arrival time of the 1394 packet in the M drive 116 becomes unnecessary.

FIG. 7 shows the relationship between the change in Nc used for encryption in STB 12 and the value of time-varying element information (Nc difference) recorded at the head of sector data. .

As described above, the value of Odd / Even bit in the 1394 packet header changes every time the value of Nc is updated. Specifically, Odd / Even
The value of bit corresponds to the value of the least significant bit of Nc actually used. Odd / Even when the value of Nc increases
Since the value of bit also changes, the receiving node can know that the value of Nc has increased.

Therefore, until the value of Nc notified from the transmitting node first changes, Odd / Even b
The value of it does not change, and the time-varying element information (difference of Nc) recorded at the head of the sector data is “0”. When the value of Nc increases to Nc + 1, the value of Odd / Even bit changes, and the time-varying element information (difference of Nc) recorded at the head of the sector data becomes "+1". Further, when the value of Nc increases to Nc + 2, the value of Odd / Even bit changes again, and the time-varying element information (difference of Nc) recorded at the head of the sector data becomes “+2”.

Next, referring to FIG. 8, MPEG2_TS
A series of processing procedures when recording a packet on the DVD-RAM drive 116 will be described.

Here, it is assumed that STB 12 operates as a digital satellite broadcast receiver as described above.

The STB 12 transmits MPEG data via an antenna.
When the 2_TS packet is received (step S11), IEC61883 is added to the head of the MPEG2_TS packet.
The source packet header (SP
H) is added (step S12). After this, STB1
2 further adds a 1394 packet header including Odd / Even bit at the beginning to create a 1394 packet for isochronous transfer (step S1).
3). When the 1394 packet is created, MPEG2_
The TS packet is encrypted. This encryption includes D
The content key generated by the authentication and key exchange processing with the VD-RAM drive 116 is used. 1394
Packet header and source packet header (SPH)
Is not encrypted. Then, the STB 12 transmits the 1394 packet to the DVD-RAM drive 116 (Step S14).

The DVD-RAM drive 116 has 139
Four packets are received (step S15). And D
The VD-RAM drive 116 stores the Odd included in the 1394 packet header of the received 1394 packet.
The presence / absence of a change in Nc is confirmed with reference to the / Even bit, and a difference of Nc is generated (step S16). After that, the DVD-RAM drive 116
The 1394 packet header is removed from the four packets, and N
After the difference of c, a 1394 packet payload is added (step S17). In this case, packet payloads having the same difference in Nc are collected, and a sector write packet having a data size of 2 Kbytes or less is generated. In this case, the source packet header (SPH) is used as it is as the time stamp for the reproduction management information.
Although a plurality of Hs are included, basically, it is only necessary that one SPH serving as a mark is added to one sector write packet. Therefore, it is also possible to select one of the plurality of SPHs and add it to the sector write packet. Thereafter, the DVD-RAM drive 116
Transmits the created sector write packet to the DVD-RA
The data is written to the write target sector position on the M medium (step S18).

In this way, the encrypted data is recorded in a state where the difference of Nc and the time stamp are added in a predetermined data size unit.

Next, with reference to FIG. 9, a description will be given of a series of processing procedures when reproducing the MPEG2_TS packet recorded on the DVD-RAM drive 116.

Here, the DVD-RAM drive 116
It is assumed that the MPEG2_TS packet recorded in the STB 12 is reproduced by the STB 12.

First, the DVD-RAM drive 116
A sector in which a data portion to be reproduced specified by reproduction control software executed by the CPU 111 or a device driver for the DVD-RAM drive 116 is recorded is searched using the SPH value as a guide, and the corresponding sector data is searched. Is read from the DVD-RAM medium (step S21). Then, a 1394 packet is generated while checking the difference of Nc corresponding to the read sector data (steps S23 and S24). Since the difference value of Nc is added to the head of the sector data, the corresponding difference value of Nc can be confirmed by one reading of the sector data. For those having the same difference value of Nc, Odd / Even in the 1394 packet header is used.
The value of bit becomes the same. The 1394 packet generated in this way is transmitted to the ST via the IEEE 1394 bus.
It is transmitted to B12 (step S25). The SPH may be newly generated.

Further, such a process of generating a 1394 packet may be performed by software executed by the CPU 111.

When the STB 12 receives the 1394 packet (step S26), it extracts the encrypted MPEG2_TS packet from the 1394 packet, performs a decryption process for decrypting the encrypted MPEG2_TS packet, and then performs
The EG2_TS packet is decoded and reproduced (step S27).

[0082]

As described above, according to the present invention,
Since digital data is recorded with the reproduction management information added to the encrypted data, an arbitrary part can be read from the middle of the encrypted data and reproduced by referring to the reproduction management information. Therefore, even during special playback such as fast-forward playback, fast-forward reverse playback, and multi-scene playback, without reading out all the encrypted data, only the encrypted data portion necessary for the special playback is read out from the recording medium and sent to the playback device side. It becomes possible to transmit. Also, by encrypting the data and the corresponding time-varying element information into packets and recording them, even in a copy protection system using the time-varying element value as an encryption key, the encrypted data unit and its decryption are required. It becomes possible to simultaneously read out the time-varying element information and transmit it to the playback device side.

[Brief description of the drawings]

FIG. 1 is an exemplary block diagram showing a system configuration of a personal computer according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between software and hardware in the system of FIG. 1;

FIG. 3 is an exemplary view showing a procedure of authentication and encryption processing used in the embodiment.

FIG. 4 shows an STB and a DVD-RA used in the embodiment.
FIG. 7 is a diagram for explaining processing executed between the M drive.

FIG. 5 is an exemplary view showing an example of a recording format of digital content used in the embodiment.

FIG. 6 is an exemplary view showing the structure of a 1394 packet used in the embodiment;

FIG. 7 is a view showing a relationship between a change in Nc and a value of time-varying element information (difference in Nc) recorded at the head of sector data in the embodiment.

FIG. 8 is an exemplary view showing a series of processing procedures when the MPEG2_TS packet is recorded on the DVD-RAM drive in the embodiment.

FIG. 9 is an exemplary view showing a series of processing procedures when an MPEG2_TS packet is reproduced in the embodiment.

[Explanation of symbols]

11 Personal computer (PC) 12 Set-top box (STB) 13 Digital video camera or DV camcorder (D
VC) 14 Digital video cassette recorder (D-VCR) 111 CPU module 112 Main memory 113 Silite or digital TV tuner 114 VGA controller 115 MPEG2 decoder 116 DVD-RAM drive 117 1394 bridge 121 Authentication unit (Authenticator) 122 ... Encryption / decryption unit (De- / Cipher) 131 ... Authentication unit (Authenticator) 132 ... Encryption unit (Cipher) 141 ... Authentication unit (Authenticator) 142 ... Encryption / decryption unit (De- / Cipher) 1111 ... Authentication unit (Authenticator) 1112 ... Decryption unit (De-cipher) 1131 ... Authentication unit (Authenticator) 1132 ... Encryption (Cipher) 1151 ... authentication unit (Authenticator) 1152 ... decoding unit (De-cipher) 1161 ... authentication unit (Authenticator) 1162 ... reproduction management information adding unit 1163 ... time-varying information management unit

Claims (11)

[Claims] 1. A data recording apparatus for recording copy-protected data, which is encrypted and transmitted from a partner device, on a recording medium while encrypting the data, and receiving the encrypted data. Means for recording, by adding, to each of a plurality of encrypted data units constituting the encrypted data received by the receiving means, reproduction management information indicating a temporal sequence relationship between the encrypted data units, Recording means for recording on a medium. 2. The encrypted data is divided into a plurality of packets each having a time stamp composed of predetermined time information for compensating for a transmission delay difference and transmitted from the destination device. 2. The data recording apparatus according to claim 1, wherein the recording unit records a time stamp added to the packet received by the receiving unit, as the reproduction management information. 3. The encryption of the data to be copy-protected is performed using an encryption key including a time variable as an encryption key generation element, and the recording unit stores the encrypted data in each of the encrypted data units. Further comprising time-varying element information adding means for adding time-varying element information for specifying the value of the time variable used for the encryption, wherein the encrypted data unit is added with the reproduction management information and the time-varying element information. 2. The data recording apparatus according to claim 1, wherein the data is recorded on the recording medium in a state where the data is recorded. 4. The encryption key is generated using the time variable and another encryption key element, and the recording unit performs an authentication process with the partner device. 2. The data recording apparatus according to claim 1, wherein the acquired other encryption key element is recorded in a predetermined area on the recording medium that cannot be read by ordinary data access. 5. A data recording apparatus for recording copy-protected data, which is encrypted and transmitted from a partner device, on a recording medium while encrypting the data, wherein the copy-protected data is encrypted. Receiving means for receiving the encrypted data, wherein the receiving means receives the encrypted data by using an encryption key generated by using the time variable as one encryption key generating element. Recording means for adding, to each of the encrypted data units constituting the data, time-varying element information for specifying the value of the time variable used for the encryption and recording the information on the recording medium. Characteristic data recording device. 6. The apparatus according to claim 5, wherein said recording means adds and records the time-varying element information in one or more encrypted data units encrypted using the same time variable. Data recording device. 7. A data recording device usable for recording digital content to be copy-protected, the device being capable of handling the digital content to be copy-protected with the other device. Authentication means for mutually authenticating each other; receiving means for receiving the copy-protected digital content encrypted and transmitted from the destination device after authentication processing by the authentication means; Means for adding time information necessary for special reproduction to the encrypted data of digital content and recording the data on a recording medium. 8. A method for recording encrypted data for recording copy-protected data, which is encrypted and transmitted from a partner device, on a recording medium while encrypting the data, the method comprising: Receiving the data, adding to each of the plurality of encrypted data units constituting the received encrypted data, playback management information indicating a temporal order relation between the encrypted data units, and adding the information to the recording medium. A method for recording encrypted data, characterized by recording. 9. A method for recording encrypted data to be recorded on a recording medium while encrypting copy-protected data, which is encrypted and transmitted from a counterpart device, wherein the copy-protected data is encrypted. The data is encrypted by using an encryption key generated by using a time variable as one encryption key generation element, receiving the encrypted data, and configuring the received encrypted data. Recording time-variable element information for specifying a value of a time variable used for the encryption to each of the encrypted data units to be encrypted and recording on the recording medium. . 10. A recording medium for recording copy-protected data encrypted and transmitted from a partner device while encrypting the data by using a predetermined data format, wherein the copy-protected data is encrypted. The recording is characterized in that the data is recorded in units of predetermined encrypted data units constituting the data and in a state where reproduction management information indicating a temporal order relation between the encrypted data units is added. Medium. 11. A recording medium for recording copy-protected data encrypted and transmitted from a partner device while encrypting the data by using a predetermined data format. The encryption is performed by using an encryption key generated by using a time variable as one encryption key generation element. The encrypted data to be copy-protected is a predetermined encrypted data constituting the encrypted data. A recording medium characterized by being recorded in a unit unit in a state where time-varying element information for specifying a value of a time variable used for the encryption is added.