JPH10271479A - Scramble/descramble method for mpeg stream data, and supply and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for simply scrambling/descrambling MPEG stream data. SOLUTION: In packetizing PES, a steam ID at a PES header is converted by a prescribed method corresponding to instructed key information (B1), and the value of PES scrambling control is changed (B2). At the time of preparing a program stream(PS), encryption key information is entered to a descriptor in a PS map packet (B3). In the case of decoding the PS, key information is segmented from the descriptor and a PES is packetized (B4). Then a value of the PES scrambling control is read (B5), and the stream ID is segmented (B6). In the processing of the succeeding step B7, the stream ID segmented in the processing of the step B6 is converted again into the original state stream ID based on the key information segmented in the processing of the step B4. Thus, the original state is restored.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for supplying and reproducing stream data encoded according to the MPEG standard. The present invention relates to a technology that enables restoration only when a predetermined descrambling process is performed on the reproduction side.

[0002]

2. Description of the Related Art Hitherto, a system using the MPEG standard has been commercialized from a technical point of view, and the security of its contents (eg, a video stream) has only been studied. Therefore, for example, MP
The EG video data reproducing apparatus adopts a method in which control header information indicated in the system part of the MPEG standard is analyzed to determine whether the data is data to be decoded, and only data that meets the conditions is decoded. Was.

[0003]

However, digital video discs (DVDs) and digital video broadcasts (D
Since the products and services based on the MPEG technology such as VB) are becoming widespread, the above-mentioned content security is an important issue. As the security, it is possible to supply scrambled data and to descramble it on the reproducing side.

Of course, since it is digital data,
Although it is possible to apply so-called “encryption” processing to the content itself, special means for encryption is required, and processing is performed in relatively small units that compose data such as bits or bytes. Because
Encrypting video data having a relatively large capacity each time is problematic in practice. And, of course, a device for decrypting the encryption is also required on the reproducing side, and similarly, the processing load for decryption is also increased.

Accordingly, the present invention has been made in view of this point, and
A method of simply scrambling and descrambling an MPEG stream (video, sound, data, etc.) by providing encryption rules for key information and software processing on both the supply side and the reproduction side based on the system standard of It is another object of the present invention to provide a supply device used for performing a scrambling process and a reproducing device used for performing a descrambling process.

[0006]

SUMMARY OF THE INVENTION In order to achieve this object, a method of scrambling and descrambling MPEG stream data according to the present invention is to encrypt stream identification data in packetized MPEG data. By doing so, a scramble state where normal system decoding cannot be performed as it is, and predetermined key information that can specify the encryption method is stored in M
The MPEG stream data set in the descriptor field shown in the system part of the PEG standard is created and supplied to the playback side. On the playback side, the MPEG stream data is packetized and set in the descriptor field. A decryption method for decrypting the encryption is specified based on the key information, and a descrambling process for restoring the encrypted stream identification data is performed by the specified decryption method. The packetized MPEG data is system-decoded based on the stream identification data.

According to the method for scrambling and descrambling MPEG stream data, when scrambling is performed on the supply side, for example, stream identification data in encoded and packetized MPEG data is encrypted. The MPEG stream data is set in a scramble state where normal system decoding cannot be performed as it is, and predetermined key information capable of specifying the encryption method is set in a descriptor field indicated in a system part of the MPEG standard. This stream data is supplied to the reproducing side.

Accordingly, even if the stream data is stolen in this state, the stream identification data is encrypted, so that, for example, video data, audio data, and the like are system-decoded (separated) from the stream data. , Proper system decoding is not possible. That is, since the stream identification data does not correspond to the content of the corresponding stream, normal reproduction cannot be substantially performed, and the data security function is exhibited.

[0009] This scrambling method is a method of encrypting stream identification data, and it is not necessary to actually encrypt stream data as contents. Therefore, it can be realized very easily. That is,
As described above, since the data is digital data, "encryption" can be performed. However, special means for encryption is required, and a relatively small unit constituting data such as a bit unit or a byte unit is required. MP, which is a relatively large capacity for contents.
There is EG video data and the like, and it is actually problematic to encrypt the data each time. On the other hand, when this method is employed, basically, only the encryption processing of the stream identification data whose data amount is very small as compared with the content data, and the processing load is small.

On the other hand, on the reproduction side, the opposite of the above-described scramble processing may be executed as descrambling processing. That is, the encryption of the stream identification data is decrypted and the original data is restored. In this case, the encryption method on the supply side must also be known on the reproduction side. For this purpose, key information set in the descriptor field is used. In other words, in the case of encryption, the key information corresponding to the encryption method is set in the descriptor field, so that the playback side knows the encryption method if the key information is known, and consequently the decryption method. Therefore, the stream can be restored to normal stream identification data according to the decryption method.

In the case of the above-described encryption of the content data itself, a device for decrypting the encryption is naturally required on the reproducing side, and similarly, the processing load for decryption increases. The present method is also advantageous in that respect. In other words, only the encryption and decryption of the stream identification data need be performed, and only the key information is used to specify the encryption method. This is very advantageous from the viewpoint of the overall processing load. is there.

In the above-described scramble / descramble method for MPEG stream data, if the key information set in the descriptor field indicates that the stream identification data has been encrypted, the MPEG standard is used. It is conceivable to set a value that can be identified to that effect in the scrambling control field in the packet header shown in the system part. This is because if scramble is applied to arbitrary stream data, stream data that is scrambled and stream data that is not are mixed, so that they can be easily identified. That's why. In other words, on the playback side,
By looking at the value of the scrambling control field in the packet header, it can be easily determined whether or not the input stream data is scrambled, and the above descrambling process may be performed only on the scrambled stream data. .

Although there are various methods of encryption, the encryption can be easily performed, for example, by rearranging the data arrangement of stream identification data. For example MP
In the EG standard, the stream identification data is composed of 8 bits, and can be realized by exchanging upper 4 bits and lower 4 bits. Of course, other methods of rearranging the data array may be used, and various types of encryption other than rearrangement of the data array may be adopted.

The MPEG stream data supply device used for performing the above-mentioned scramble processing stores, for example, a correspondence relationship between key information and a stream identification data encryption method. Encryption method storage means, scramble control means for encrypting the stream identification data in the packetized MPEG data, so as to perform a scramble state in which normal system decoding cannot be performed as it is, and When the MPEG data is converted into a multiplexed stream, key information corresponding to a method of encrypting stream identification data applied by the scramble control means is read out from the storage means, and a descriptor indicated in a system part of the MPEG standard is read. Key to set in the field And a distribution setting unit, it is considered that and supplying the set MPEG stream data for the key information.

[0015] As an apparatus for reproducing MPEG stream data used for performing the descrambling process, for example, as described in claim 5, the MPEG stream supplied from the MPEG stream supply apparatus according to claim 4 is provided.
A playback device capable of playing back G stream data, a decryption method storing means for storing a correspondence between a method for decrypting encryption to the stream identification data and key information, and packetizing the MPEG stream data. Packetizing means, and a corresponding decryption method is read from the decryption method storage means based on the key information set in the descriptor field, and the encrypted stream identification data is read by the decryption method. Descramble control means for restoring, and system decoding means for system decoding the packet data based on the restored stream identification data,
It is conceivable that the system-decoded packet is decoded and reproduced.

The contents of scramble processing and descrambling processing executed in the MPEG stream data supply apparatus and the reproduction apparatus, and the functions and effects of the contents.
The effect is the same as that described above, so it is omitted here,
The correspondence stored in the encryption method storage and the correspondence stored in the decryption method storage will be further supplemented.

These are stored as an encryption method and a decryption method corresponding to the key information set in the descriptor field. Therefore, if, for example, the key information “01” is set on the supply device side, for example, corresponding to the above-described encryption method for exchanging the upper 4 bits and the lower 4 bits, the reproduction device side sets the key information “01”. Similarly, a method of exchanging the upper 4 bits and the lower 4 bits is set as the decryption method corresponding to “01”.

[0018] Even when the MPEG stream data is supplied or reproduced, the key information set in the descriptor field encrypts the stream identification data in the same manner as described above. If it indicates that
It is preferable to set a value for identifying the effect in the scrambling control field in the packet header shown in the system part of the MPEG standard.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart illustrating the concept of a scramble / descramble method for a program stream conforming to MPEG.
B1 to B3 in the figure indicate processing related to scrambling.
4 to B7 indicate processes related to descrambling.

Before describing FIG. 1, a program stream (PS) and a program stream map (PSM) appearing in the following description of each process will be described.
The data structure of the packet and the PES packet in the program stream will be described.

Data Structure of Program Stream (PS) FIG. 2 shows a hierarchical structure of the data structure of the PS. In the first pack, a packet is arranged after a pack header and a system header in the first pack. , A packet is placed immediately after the pack header, and an end code is added at the end.

The pack header is a pack start code,
"10", SCR (System Clock Reference), multiplex rate, stuffing length, and stuffing byte. On the other hand, the system header is composed of a system header start code, header length, bit rate,
It consists of 4 flags of 5 bits including the number of audio channels, marker bits, 5 bits of video channels, reserved bytes, and N-loop basic stream information. Then, in this N loop basic stream information,
There is a stream ID (SID).

Program stream map (PSM)
Data Structure of Packet A packet for PSI (program specification information) is defined in the PS, and a program stream map (PSM)
The packet is exactly the PSI packet. The PSM packet is a packet describing additional information of the program and additional information of each individual stream.

As shown in FIG. 3, N-loop individual stream information is a component of the PSM packet.
The loop individual stream information includes a stream type, an individual stream ID, an individual stream information length, and an N loop descriptor. The N loop descriptor includes a descriptor tag, a descriptor length, descriptor data, and the like.

Data Structure of PES Packet As shown in FIG. 4, the PES packet has a format commonly used for video and audio, and is roughly composed of a header portion and an effective data portion. The header part includes a packet start code prefix, an 8-bit stream ID, a PES packet length, and an optional PES.
Consists of a header. The effective data portion is composed of 8 × N-bit PES packet data bytes.

The optional PES header in the header section has a 2-bit value "1" for discrimination from MPEG1.
0 "or a 2-bit PES scrambling control flag for scrambling data and using it for confidential information or a commercial billing system, and a P for discriminating important packets from non-important packets depending on the application.
ES priority flag, data alignment indicator,
Copyright, original or copy, other 7 flags,
It includes a PES packet data length, an optional field, a stuffing byte, and the like.

Next, FIG. 1 will be described. (1) Scramble-Related Processing In the first processing B1 in FIG. 1, when the encoded stream is converted into a PES packet, the stream ID (see FIG. 2) in the PES header is changed to a predetermined method corresponding to the designated key information. To convert. For example, stream I
Since D (SID) is indicated by 1 byte, the upper 4 bits and lower 4 bits of the SID are exchanged. FIG. 6 shows a stream ID table (stream ID table) in which the correspondence between the stream ID and the stream type is set. For example, the stream ID of the MPEG audio stream is defined as “110xxxxxx”, and the stream ID of the MPEG video stream is It is defined as "1110xxxx". Therefore, when the upper 4 bits and the lower 4 bits of each SID are exchanged, the stream ID of the MPEG audio stream becomes “xxxx110x”.
And the stream I of the MPEG video stream
D is converted to “xxxx1110”.

In the process B2, the value of the PES scrambling control (see FIG. 4) in the PES packet in the program stream is changed based on the MPEG standard. This PES scrambling control flag is prepared by 2 bits, and as shown in FIG.
For the four values “01”, “10”, and “11”, “0”
If "0", do not rearrange the position "not scrambled"
Is defined, and the remaining “01”, “10”, and “11” are “user defined”, and the user is allowed to set. Therefore, when the PES packet is formed, the data to be scrambled is specified by setting the PES scrambling control flag in the header portion to any one of “01”, “10”, and “11”.

In this way, the stream ID (SID)
Is converted into a program stream (PS) through a predetermined multiplexing process. In the process B3, a program stream map (PS) is generated when the PS is created. Key information for encryption is input to the descriptor (see FIG. 3) in the PSM) packet. This is the same key information as when the SID was converted in the process B1. Note that this key information is input to a portion of the descriptor that can be used freely by the user.
As can be seen from the descriptor table, “UserPrivate” is used for descriptor tags 64 to 255.
And it is. This part is a part that can be used freely by the user. (2) Descramble-related processing When decoding, as shown in the processing of B4 in FIG.
Key information is extracted from the descriptor (see FIG. 3) in the program stream map packet in the input program stream. At the same time, processing up to PES packetization is performed.

In the subsequent process B5, the value of the PES scrambling control (see FIG. 4) in the PES packet is read. Then, in the process of B6, the PES of the PES packet
The stream ID (see FIG. 2) in the ES header is cut out. The cut-out stream ID (SID) is in a state where, for example, the upper 4 bits and the lower 4 bits encrypted in the process of B2 at the time of encoding are exchanged.

In the following process B7, the stream ID (SID) cut out in the process B6 is reconverted to the original SID based on the key information cut out in the process B4. That is, when the encryption is performed by exchanging the upper 4 bits and the lower 4 bits, the original state is restored by exchanging them again.

Since the descramble process is executed by the processes of B4 to B7, in the subsequent process of B8, the system decode process is performed based on the SID returned to the original state. That is, it is determined whether the packet is a video PES packet or an audio PES packet, and the output destination is changed accordingly.
Thereby, an appropriate stream can be reproduced.

The concept of the scramble / descramble method for the program stream conforming to the MPEG has been described above. Next, the program stream is supplied from the information supply device 20 adopting the scramble method, and the descramble method is executed. The configuration and specific operation of the information supply / reproduction system 10 that reproduces information using the information reproduction apparatus 100 that employs the following will be described.

As shown in FIG. 8, the information supply / reproduction system 10 includes an information supply device 20 and an information reproduction device 100,
They are connected via a transmission line 90 composed of a coaxial cable or the like. The information supply device 20 is provided with an encoding device 50. Although only one information reproducing apparatus 100 is shown in FIG. 8, a plurality of information reproducing apparatuses 100 are generally connected to one information supply apparatus 20. Further, the transmission path 90 may be of any type regardless of whether it is wired or wireless.

The configuration of the information supply device 20 will be described. The information supply device 20 uses the PE
S-packetized MPEG video data and MPEG audio data are multiplexed into an information reproducing apparatus 1
It is a device for supplying to 00. As shown in FIG.
The encoding device 50 includes a video encoder 51, a video PES packetizer 52, and an audio encoder 5.
3 and an audio PES packetizer 54.

The video encoder 51 is capable of encoding an analog video signal input from the outside and converting it into a digital data sequence. The video signal converted into the digital data sequence is processed by a video PES packetizer 52.
In this case, PES packets are formed according to the MPEG2 standard and output as video PES packets.

Similarly, the audio encoder 53 can encode an externally input analog audio signal and convert it into a digital data string. The audio signal converted into the digital data string is an audio PES.
According to the MPEG2 standard, the packetizer 54
It is converted into S packets and output as audio PES packets.

The video PES packet output from the video PES packetizer 52 is input to the input interface 21, and the audio PES packet output from the audio PES packetizer 54 is input to the input interface 22. The video PES packet input to the input interface 21 is transmitted to the bus 24
The audio PES packet transferred to the video buffer memory 31 via the input interface 22 is transferred to the audio buffer memory 32 via the bus 24. The video buffer memory 31 can temporarily store the transferred video data and output it in response to a request from the multiplexer 35. Similarly, the audio buffer memory 32 can temporarily store the transferred audio data and output the audio data in response to a request from the multiplexer 35.

Multiplexer 35 as multiplexing means
Is a PES packet sequence of video data read from the two buffer memories 31 and 32 and a PES packet of audio data.
A packet stream can be multiplexed to create one program stream (PS) and output to the head end 37 through the output interface 36.

Although not shown, the information supply device 20 is provided with a plurality of data output mechanisms including the above-described video buffer memory 31, audio buffer memory 32, multiplexer 35 and output interface 36. The head end 37 can transmit the PS transmitted from the plurality of data output mechanisms to the transmission path 90 through the channel allocated to each output interface 36. In addition, the head end 37 can transmit a signal transmitted from the modem 47 through a channel for bidirectional communication, and can transfer a signal input from the transmission line 90 through a channel for bidirectional communication to the modem 47. .

The modem 47 is connected to the central control unit 30 as control means via the bus 24, and the central control unit 30
Information reproducing apparatus 100 connected by transmission line 90
, Or receive data from the information reproducing apparatus 100.

The central control unit 30 can control the operation of each unit of the information supply device 20 described above.
When a PES packet is created in the encoding device 50 or the video PES
When a program stream is created by multiplexing a packet and an audio PES packet, a predetermined scramble-related process can be instructed.

The above-mentioned central control unit 30 corresponds to "encryption method storage means", and the central control unit 30 and the video PE
The S packetizer 52 and the audio PES packetizer 54 correspond to “scramble control means”. And
The central control unit 30 and the multiplexer 35 correspond to “key information setting means”.

Next, the configuration of the information reproducing apparatus 100 will be described with reference to FIG. The information reproducing apparatus 100 transmits the program stream (PS) transmitted from the information supply apparatus 20 via the transmission path 90 to the external input I / F 1.
10, the received PS is separated by the system decoder 120 into a video PES packet stream and an audio PES packet stream.

In the system decoder 120, an RO storing a processing program of the system decoder 120 is stored.
M121 and a RAM 12 which corresponds to a "decoding method storage means" and also functions as a work of the system decoder 120.
2 are connected. Also, the system decoder 120
Includes a video PES transfer buffer 120a and an audio PES transfer buffer 120b. Then, the video PES packet and the audio PES packet on the video PES transfer buffer 120a and the audio PES transfer buffer 120b are transferred via a video channel and an audio channel to an audio / video decoder (hereinafter abbreviated as A / V decoder). .) 130
Is input to It should be noted that the present system decoder 120
It corresponds to "packetizing means", "descrambling control means", and "system decoding means".

The A / V decoder 130 MPEG-decodes the input video PES packet and audio PES packet. The A / V decoder 130 has a RAM for work of the A / V decoder 130.
135 and a CPU 140 as control means for controlling the A / V decoder 130 are connected.

The CPU 140 includes a ROM 141 in which a program for the CPU 140 is stored,
A work RAM 142 is connected to the system decoder 120, and information can be exchanged with the system decoder 120. Also, the A / V decoder 13
The digital video data output from the digital video output 0 is input to the video DA converter 150,
The video DA converter 150 converts the video signal into an NTSC signal, which is a video signal of a television, and outputs the signal to an external device.
On the other hand, the digital audio data output from the digital audio output of the A / V decoder 130 is input to the audio DA converter 155, and is converted into an analog audio signal by the audio DA converter 155 and output to the outside.

The A / V decoder 130 uses the system decoder 120 to output video PES packets and audio PEs.
Each packet classified into S packets is input from an audio channel and a video channel. In the A / V decoder 130, the header part and the effective data part of each packet of audio and video are separated, and each is separated into a header buffer (Header Buffer).
And input to a channel buffer (Channel Buffer), MPEG-encode the data in both the video and audio channel buffers, and output digital video data and digital audio data from digital video output and digital audio output respectively. Is output.

The information supply / reproduction system 10 having the above configuration
Then, scrambling and descrambling of MPEG stream data is executed as follows. First, processing related to scrambling executed in the information supply device 20 will be described with reference to the flowcharts in FIGS.

The flowchart shown in FIG. 11 is a process executed by the video PES packetizer 52 or the audio PES packetizer 54 of the encoding device 50 (see FIG. 9). In the first step S1, it is determined whether or not the encoded stream data is END. If it is determined that the encoded stream data is not END (S1: NO), the process proceeds to S2, and the scramble instruction is sent to the central control unit. It is determined whether the number is from 30. If not (S2: NO), the process proceeds to S5 to create a PES packet, transmits the PES packet in S6, and returns to the first step S1.

On the other hand, if there is a scramble instruction (S2: YES), the flow shifts to S3, where the stream ID (see FIG. 4) in the PES header is determined based on the key information specified by the central control unit 30. Is converted by the following method. This is, for example, as described above, the upper 4
This is a process of exchanging bits and lower 4 bits.

Thereafter, in S4, the value of the PES scrambling control (see FIG. 4) in the PES header is changed to "01" here. As described above, "01",
For the three values "10" and "11", use "user defin
Since it is set to "ed" and the user is allowed to set, it is set so that the scramble can be specified by "01". After that, the processing of S5 and S6 described above is executed.

If it is determined in S1 that the data for the encoded stream is END (S1:
YES), this process ends. On the other hand, the flowchart of FIG. 12 is a process executed by the multiplexer 35.

In the first step S11, it is determined whether or not the encoded stream data is END. If it is determined that the encoded stream data is not END (S11: NO), the process proceeds to S12 and a scramble instruction is issued. It is determined whether or not there is a central control unit 30.
If not (S12: NO), the process proceeds to S14 to create a program stream (PS) as usual, and S15
Is sent to return to the first step S11.

On the other hand, if there is a scramble instruction (S12: YES), the flow shifts to S13, where the descriptor (see FIG. 3) in the program stream map (PSM) is added to the key corresponding to the stream ID (SID) conversion. Set information. The SID is converted in S3 of FIG. 11, which is based on the key information specified by the central control unit 30. The central control unit 30 stores the key information and the PES
The key information is stored in the multiplexer 35 together with the scramble instruction. Therefore, the notified key information is set. After that, S14, S described above
15 is executed.

If it is determined in S11 that the encoded stream data is END (S1
1: YES), this process ends. Next, descrambling-related processing executed in the information reproducing apparatus 100 will be described with reference to the flowchart in FIG.

FIG. 13 shows a system decoder 120.
(See FIG. 10). In addition,
Although not described in detail, at the time of decoding, key information is cut out from a descriptor (see FIG. 3) in a program stream map packet of the input program stream, and processing up to PES packetization is performed. Therefore, this process is a process performed after the PS is converted into the PES packet.

In the first step S21, it is determined whether or not the PES packet is END. PES packet is EN
If it is determined that it is not D (S21: NO), S2
The process proceeds to 2 to determine whether the PES scrambling control value in the PES header is “01”. When it is determined that the PES scrambling control value is “01” (S23: YES), the process proceeds to S23 to acquire key information, and in S24, the SID is reconverted based on the key information. That is, it returns to the original state.

Then, in S25, a normal system decoding process, that is, whether it is a video PES packet or an audio PES packet, is determined.
In accordance with this, distribution to the video PES transfer buffer 120a and the audio PES transfer buffer 120b is performed.

If it is determined that the PES scrambling control value is not "01" (S22: N
O) The process proceeds to S26 to determine whether the PES scrambling control value is "00". A positive determination is made in S26, that is, the PES scrambling control value
0 (not scrambled) "
The process proceeds to S25 to perform a system decoding process.

If a negative judgment is made in S26, it means that the PES scrambling control value is "10" or "11", and a different scrambling method is set, so that system decoding cannot be performed. . Therefore, this processing ends.

In S21, if it is determined that the PES packet is END, the process is terminated.
As is apparent from the above description, in the information supply / reproduction system 10, when scrambling is performed by the information supply device 20, the stream ID in the packetized MPEG data is encrypted, and the information is normally returned as it is. The system is in a scrambled state that cannot perform proper system decoding. At the same time, a program stream (PS) in which predetermined key information capable of specifying the encryption method is set in a descriptor field indicated in the system part of the MPEG standard is created, and this PS is supplied to the reproducing side. .

Therefore, in this state, for example, PS
Is stolen, even if an attempt is made to system-decode (separate), for example, video data or audio data from the PS, since the stream ID is encrypted,
Cannot perform proper system decoding. That is, since the stream ID does not correspond to the contents of the corresponding stream, normal reproduction cannot be substantially performed, and the data security function is exhibited.

This scrambling method is a method of encrypting an 8-bit stream ID in the present embodiment, and it is not necessary to encrypt video data and audio data as contents. It can be easily realized. In other words, although it is possible to apply "encryption" to such video data and audio itself, special means for encryption is required, and relatively small data that constitutes data in units of bits or bytes is required. Since the processing is performed in units, it is practically problematic to perform encryption on MPEG video data having a relatively large capacity each time. On the other hand, in the case of the present embodiment, basically, only the encryption processing of the stream ID whose data amount is very small as compared with the content data is small, and the processing load is small.

On the other hand, the information reproducing apparatus 100 decrypts the encryption of the stream ID and returns the data to the original normal data.
In this case, the encryption method on the information supply device 20 side must also be known on the information reproduction device 100 side. For this purpose, key information set in the descriptor field is used. That is, in the case of encryption, key information corresponding to the encryption method is set in the descriptor field, so that the information reproducing apparatus 100 can determine the encryption method if the key information is known, and as a result, Since the decryption method is known, a normal stream ID can be restored according to the decryption method.

In the case of encrypting the content data itself, a device for decrypting the encryption is naturally required on the information reproducing apparatus 100 side, and the processing load for decrypting the decryption is also large. However, in the case of the present embodiment, this is also advantageous. That is, only the stream ID encryption process and the decryption process are required, and only the key information is used to specify the encryption method. This is very advantageous from the viewpoint of the overall processing load. .
Further, in the present embodiment, when the key information set in the descriptor field indicates that the stream ID has been encrypted, a value capable of identifying the fact is set in the PES scrambling control field. I tried to keep it. This is because if stream data is scrambled arbitrarily, stream data that is scrambled and stream data that is not are mixed, so that they can be easily identified. That's why. That is, the information reproducing apparatus 100 can easily determine whether or not the input stream data has been scrambled by looking at the value of the PES scrambling control, and can perform the above descrambling only on the scrambled stream data. It will be good if it performs processing.

As described above, according to the information supply / reproduction system 10 of the present embodiment, the system decoding cannot be performed simply by taking advantage of the fact that the system cannot be decoded unless the stream ID of the MPEG stream data is a value specified in the MPEG standard.
PEG stream data can be scrambled. Although video and audio have been described as contents in the present embodiment, private data and the like may be included in addition to the contents.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various forms without departing from the gist of the present invention. For example, in the above embodiment, since the program stream (PS) is assumed as the MPEG stream data, the key information is set in the “descriptor” existing in the program stream map (PSM) packet. ), Key information may be set in a descriptor field that can be set according to the MPEG standard, such as using a descriptor in a program map table (PMT).

In the above embodiment, the stream ID
Upper 4 bits and lower 4 bits of stream ID
Although the technique of exchanging bits is employed, other techniques may be employed when the technique is performed by rearranging data arrays. Further, instead of rearranging the data array, various other encryption methods may be employed.

In the above embodiment, scrambling is performed on the stream ID in the video PES packet and the audio PES packet. However, for example, the stream ID in the system header of the program stream shown in FIG. Scramble may be applied. In this case, double scrambling is performed, and it is considered that the degree of security is further improved.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating the concept of a scramble / descramble method according to an embodiment for a program stream compliant with MPEG.

FIG. 2 is an explanatory diagram showing a hierarchical structure of MPEG program stream data.

FIG. 3 is an explanatory diagram showing a data configuration of a program stream map packet.

FIG. 4 is an explanatory diagram showing a data configuration of a PES packet.

FIG. 5 is an explanatory diagram of a descriptor table.

FIG. 6 is an explanatory diagram of a stream ID table.

FIG. 7 is an explanatory diagram of four values of a PES scrambling control flag.

FIG. 8 is a block diagram mainly showing a configuration of an information supply device side of the information supply / reproduction system.

FIG. 9 is a block diagram illustrating a configuration of an encoding device.

FIG. 10 is a block diagram illustrating a configuration of an information reproducing apparatus.

FIG. 11 is a flowchart illustrating a process related to scrambling executed in the information supply device.

FIG. 12 is a flowchart illustrating processing related to scrambling performed in the information supply device.

FIG. 13 is a flowchart showing a process related to descrambling executed in the information reproducing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Information supply system 20 ... Information supply device 30 ... Central control part 31 ... Video buffer memory 32 ... Audio buffer memory 35 ... Multiplexer 36 ... Output interface 37 ... Head end 50 ... Encoding device 51 ... Video encoder 52 ... Video PES packetizer 53 ... Audio encoder 54 ... Audio PES packetizer 100 ... Information reproducing device 110 ... External input I
/ F 120: System decoder 120a: Video PES transfer buffer 120b: Audio PES transfer buffer 121: ROM 122: RAM 1
30 A / V decoder 131 Pre-processing unit 132 Post-processing unit 1
35 RAM 136 Video PES header buffer 137 Audio PES header buffer 138 Video channel buffer 139 Audio channel buffer 140 CPU 141 ROM 1
42 RAM 150 Video D / A converter 155 Audio D / A converter

Claims (5)

[Claims] 1. Encrypting stream identification data in packetized MPEG data to a scramble state in which normal system decoding cannot be performed as it is, and providing predetermined key information capable of specifying the encryption method. MP set in the descriptor field shown in the system part of the MPEG standard
The EG stream data is created and supplied to the reproducing side. On the reproducing side, the MPEG stream data is packetized and decryption for decrypting the encryption is performed based on the key information set in the descriptor field. A descrambling process for restoring the encrypted stream identification data according to the identified decryption method, and executing the packetized M based on the restored stream identification data.
A method for scrambling and descrambling MPEG stream data, comprising system decoding PEG data. 2. When the key information set in the descriptor field indicates that stream identification data has been encrypted, the key information in the packet header indicated in the system part of the MPEG standard is used. 2. The MPEG according to claim 1, wherein a value for identifying the fact is set in the scrambling control field.
A method for scrambling and descrambling stream data. 3. The method according to claim 1, wherein the encryption is performed by rearranging the data arrangement of the stream identification data. 4. An encryption method storing means for storing a correspondence relationship between key information and an encryption method of stream identification data, and by encrypting stream identification data in packetized MPEG data. A scramble control unit for setting a scramble state in which normal system decoding cannot be performed as it is, and a method for encrypting stream identification data performed by the scramble control unit when multiplexing the packetized MPEG data. Key information setting means for reading key information to be set from the storage means and setting the information in a descriptor field indicated in a system part of the MPEG standard, and supplying MPEG stream data in which the key information is set. MPEG stream data Data supply device. 5. A playback device capable of playing back MPEG stream data supplied from the MPEG stream supply device according to claim 4, wherein a method for decrypting encryption of the stream identification data and key information are provided. Decryption method storage means for storing the correspondence, packetization means for packetizing the MPEG stream data, and corresponding decryption from the decryption method storage means based on the key information set in the descriptor field. A descrambling control means for reading the method and restoring the encrypted stream identification data by the decryption method, and a system decoding means for system decoding the packet data based on the restored stream identification data. And decode the system-decoded packet. Reproducing apparatus of the MPEG stream data, wherein the play.