JP2003244127A - Digital content processing device, digital broadcast receiver, digital content processing system, digital broadcast system, digital content processing method, computer readable storing medium, computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to carry out viewing control surely for program information stored in a storage in a server-type broadcast. <P>SOLUTION: The digital content processing device for treating digital contents and meta-information about the digital contents includes a management means for holding first control information used for controlling the meta-information and managing the first control information by using input second control information, and a control means for controlling the usage of the digital contents or the meta-information on the basis of the first control information. Then, the viewing control at a desired time can be carried out. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

The present invention relates to a digital content processing device, a digital broadcast receiving device, a digital content processing system, a digital broadcasting system, a digital content processing method, a computer-readable storage medium and a computer program. For more details,
The present invention relates to a content use control system capable of controlling the use of content even in the case of delivering content to a content receiver having a storage function, and in particular, a receiver having a storage function,
The present invention relates to a technique suitable for use in a broadcasting system for receivers that also has a network connection function.

[0002]

2. Description of the Related Art With the recent trend of digitization, digitization is being advanced in various fields. In the field of broadcasting, digitalization is being promoted, and digital broadcasting is partially realized.

In digital broadcasting, since it is possible to transmit meta information describing the program contents together with the broadcast program, a receiver having a large-capacity storage function (hereinafter referred to as "storage") stores these information. Utilizing this, new services are being proposed that take advantage of the benefits of digital broadcasting, such as automatic storage of programs, scene search, and digest viewing.

TV Any is being studied internationally.
Some progress is being made in the discussion on meta-information, etc. in the technical discussions on the broadcasting system centered on the Time Forum.

In addition, with the recent increase in capacity of hard disks, hard disk recorders for recording digital broadcast contents have already been put on the market, and the environment for realizing such services has been prepared, and digital services have been established. In broadcasting, measures to protect broadcast contents from illegal copying are also required as essential.

A receiver having a large-capacity storage function is
Since it is also expected to function as a home server, such as the connection function with the Internet and other information appliances,
It is called "server-type receiver", and broadcasting for server-type receivers is called "server-type broadcasting".

On the other hand, conventionally, as a pay broadcasting system, a conditional access system applied to television broadcasting and high definition television broadcasting (hereinafter referred to as high definition broadcasting) has been widely studied.

The video signal and the audio signal generally broadcast by the pay system are scrambled (stirred) by some method so that they cannot be received by a person other than the person who is permitted to receive them, and the reception is permitted. A person controls the reception by sending a signal for restoring the scrambled signal.

The information sent as a signal for controlling the reception is called related information, and the information of the key (scramble key) for restoring the scramble and the broadcast program are within the contract range of each receiver. It includes information for determining whether or not the broadcasting station is present, information for forcibly turning on / off a specific receiver from the broadcasting station, and the like.

When paying television or high-definition television by satellite broadcasting, the related information is transmitted in the form of packets on the data channel. In this case, the scramble key and information about the broadcast program (this is called program information) are encrypted so that they will not be known or tampered with by a third party. The key for this encryption is called a work key, and is separately sent to the recipient together with the contract information indicating the contract contents of each recipient.

This related information is called individual information, and is transmitted by broadcast radio waves, physical media such as IC cards and magnetic cards, and telephone lines. Of these, when transmitting by radio waves, it is always necessary to encrypt, and the key used for this encryption is called the master key, and in principle differs for each recipient.

FIG. 11 shows an example of the configuration of a system for performing such scrambling. In FIG. 11, a scramble unit 1111, a multiplexing unit 1112, and an encryption unit 1113 represent the broadcasting device 1110 on the broadcaster side.

Further, a separation unit 1121, a descrambling unit 1122, a decoding unit 1123, and a viewing determination unit 1124 represent the receiving device 1120 side of the receiver 14.

As shown on the broadcaster side of FIG.
The broadcaster scrambles the program information with the scramble key, encrypts the scramble key with the work key, and encrypts individual information consisting of the work key and contract information with the master key,
Information obtained from each is multiplexed and broadcast.

As shown on the receiver side in FIG. 11, the receiver 1120 of the receiver 14 separates the received information,
Individual information encrypted using the master key that is held in advance is decrypted, the encrypted scramble key is decrypted using the work key obtained by decryption, and the scramble key and contract information obtained by decryption By using the scrambling key, the program information is descrambled when the viewing is determined by the user.

Further, the decryption unit 1123 and the viewing determination unit 1124 on the side of the recipient 14 need to store the master key safely, and prevent the recipient 14 from seeing the work key and scramble key obtained during the processing. In many cases, it is implemented in a medium such as an IC card that is resistant to external fraud.

[0017]

The conventional recipient-only method is intended for broadcasting. That is, the broadcast program was directly delivered in real time from the broadcaster to the receiver 14 through a communication medium called radio wave broadcasting. This is the recipient 14
Represents that the viewing control is sequentially performed when the radio wave is received.

On the other hand, in server type broadcasting, not only radio wave broadcasting but also storage of program information in a storage is assumed. In other words, it is conceivable to access the content stored in the storage at any time, and it is necessary to control viewing at any time. But,
In the conventional receiver-only method, viewing control for arbitrary time is not considered.

For example, in the conventional receiver-only method, when the viewing control for an arbitrary time is realized by including the description about the valid time information in the contract information, the IC card used for the judgment of the contract information has the correct time. Since information cannot be stored, tampering with the time information may allow unauthorized viewing.

On the other hand, it is conceivable to rewrite the contract information itself, that is, a measure by updating the contract information. However, as described above, the individual information including the contract information is multiplexed with the program information.

Therefore, updating the contract information means separating the multiplexed information, extracting the contract information, updating the extracted contract information, and re-multiplexing using the updated contract information and program information. Need to be converted. Usually, it is very difficult to configure them with a receiver that does not have a multiplexing function or a coding function.

Furthermore, it may be considered that the contract information and the program information are held separately. In this case, a new problem arises in that it is necessary to simultaneously judge whether the contract information to be judged at the same time as the contract information is judged.

The present invention has been made in view of the above problems, and it is a first object of the present invention to make it possible to reliably perform viewing control on program information stored in a storage in server type broadcasting. The purpose of. A second object of the present invention is to provide a system in which already realized programs are compatible with existing systems including BS digital broadcasting, which is a distribution system.

[0024]

A digital content processing apparatus of the present invention is a digital content processing apparatus that handles digital content and meta information about the digital content, and first control information for controlling the meta information. And a control means for controlling the use of the digital content or the meta information according to the first control information, the management means holding the first control information according to the input second control information. And means. Another feature of the present invention is that the first control information is an encryption key in a common key cryptosystem. Another feature of the present invention is that the management means manages the first control information by deleting the encryption key. Another feature of the present invention is that the management means manages the first control information by updating the encryption key. Another feature of the present invention is that the first control information is a decryption key in a public key cryptosystem. Another feature of the present invention is that the management means manages the first control information by an invalidation list in the public key cryptosystem. In addition, other features of the present invention include:
The first control information is associated with the digital content or the meta information. Further, another feature of the present invention is that the first control information is associated with a distributor of the digital content or the meta information. In addition, other features of the present invention include:
The managing means for managing the first control information is characterized by being realized by a medium that is difficult to be illegally operated.

A digital broadcast receiving apparatus of the present invention uses the digital content processing apparatus according to any one of the above,
It is characterized by handling broadcast contents which are the digital contents.

A digital content processing system of the present invention is characterized by including the digital content processing device described in any one of the above.

A digital broadcasting system of the present invention is characterized by including the digital content processing device described in any one of the above.

The digital content processing method of the present invention comprises:
A digital content processing method for handling digital content and meta information relating to the digital content, wherein first control information for controlling the meta information is held on a medium, and the first control information is held by input second control information. It has a management step of managing the first control information, and a control step of controlling the use of the digital content or the meta information by the first control information. Another feature of the present invention is that the first control information is an encryption key in a common key cryptosystem. Further, another feature of the present invention is that the management step manages the first control information by deleting the encryption key. Another feature of the present invention is that the managing step manages the first control information by updating the encryption key. Another feature of the present invention is that the first control information is a decryption key in a public key cryptosystem. In addition, as another feature of the present invention, the management step is
It is characterized in that the first control information is managed by an invalidation list in the public key cryptosystem. Further, another feature of the present invention is that the first control information is associated with the digital content or the meta information. Also,
Another feature of the present invention is that the first control information is associated with a distributor of the digital content or the meta information. Further, another feature of the present invention is that the medium holding the first control information is realized by a medium that is difficult to be illegally operated.

The storage medium of the present invention is characterized by recording a program for causing a computer to function as each of the above-mentioned means. Another feature of the storage medium of the present invention is that a program for causing a computer to execute the digital content processing method described above is recorded.

The computer program of the present invention is characterized by causing a computer to execute the above-described digital content processing method.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a digital content processing apparatus, a digital broadcast receiving apparatus, a digital content processing system, a digital broadcasting system, a digital content processing method, a computer-readable storage medium, and a digital content processing apparatus according to the present invention will be described with reference to the accompanying drawings. An embodiment of a computer program will be described. Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration example of a system according to an embodiment of a digital broadcasting system of the present invention. The embodiment includes a single or a plurality of managers, a single or a plurality of broadcasting companies, a single or a plurality of meta information providing companies 13 and a plurality of receivers 14. Each is interconnected by various communication media.

In FIG. 1, an administrator 11 manages the operation of the entire system. That is, it manages issuance of keys used in the system. In FIG. 1, a broadcasting company 12 is an entity that provides program information by broadcasting, and generally corresponds to a broadcasting station. However, the embodiments are not limited to inventions particularly limited to video broadcasting, but may be applicable to music broadcasting such as radio broadcasting and general content broadcasting such as data broadcasting. it is obvious. In the embodiment, these broadcast contents are collectively called program information.

In FIG. 1, the meta information provider 13 is
It is an entity that provides meta information that describes the program content. In the conventional broadcasting, the meta-information provider 13 is the same entity as the broadcasting company 12, but this is not the case when the server-type broadcasting is assumed.

Further, in server type broadcasting, it is assumed that program information is stored in a storage medium, and similarly, storage of meta information is also assumed. Furthermore, since the server-type receiver has a network connection function, it is also assumed that the meta-information is received independently of the program information via the network, the communication satellite 15, and the like.

That is, the meta information can be provided at an independent time or an independent communication medium regardless of the distribution time of the program information or the communication medium, and can be easily performed by an entity other than the broadcaster 12. Shows.

In FIG. 1, the receiver 14 is an entity that receives program information and views the program.

A communication medium called a radio wave broadcast including a communication satellite 15 is typically used between the broadcaster 12 and other entities, but other communication media such as an optical fiber can also be used. Further, between the receiver 14 and the meta-information provider 13 is not only a one-way communication medium called radio wave broadcasting via the broadcaster 12, but also various bidirectional networks such as a telephone line network, a mobile phone network, and a cable TV network. Communication media also exist. The broadcaster 12 may be the meta information provider 13. Further, the broadcasting company 12 may become the manager 11.

In the embodiment, the broadcaster 1
2 or the limited distribution of the program information or the meta information from the meta-information provider 13 to the receiver 14, as shown in FIG. 2, scrambling or encryption using a key as in the conventional receiver-limited method. It is realized by

Although FIG. 2 shows a diagram in which only basic elements are extracted for simplifying the structure, it also corresponds to an encryption method or scramble method having a hierarchical structure which is actually used. It is possible.

In the recipient-only broadcasting, if the key can be shared between the broadcaster 12 or the meta information and the recipient 14,
Program information or meta information can be descrambled or decoded, and program information or meta information can be used,
When the key cannot be shared between the broadcaster 12 or the meta information and the receiver 14, it is realized because the program information or the meta information cannot be descrambled or decrypted and the program information or the meta information cannot be used.

Furthermore, since the server type broadcasting is assumed in the embodiment, the receiver 14 has the storage 21 as a large capacity storage function as shown in FIG. The storage 21 stores program information and meta information provided to the recipient 14 via various communication media.
In addition, the program limited to the program information and the meta information stored in the storage 21 are also limited to the recipient using the above-mentioned key.

FIG. 3 shows an example of the configuration of the broadcaster 12 and the receiver 14. As shown in FIG. 3, the broadcaster 12 and the receiver 14 are connected by a communication medium 31. In FIG. 3, the broadcasting company 12 includes an encryption unit 121 and a multiplexing unit 12.
2 and the first key management unit 123.

The encryption unit 121 includes a first key management unit 123.
The program information is encrypted using the key input from. Various encryption algorithms can be used, and there is no particular limitation.

The multiplexing unit 122 multiplexes the key management information input from the first key management unit 123 and the encrypted program information input from the encryption unit 121 as needed.
The first key management unit 123, as shown in FIG.
1 and the key storage unit 42.

The key storage unit 42 stores a plurality of keys, and the key processing unit 41 manages generation and deletion of these keys. Further, the key processing unit 41 outputs the stored key in response to the request, and further outputs the key management information for managing the key.

The key management information is output to the multiplexing unit 122,
It may be transmitted to the recipient 14 after being multiplexed with the encrypted program information, or may be transmitted directly to the recipient 14 via a communication medium.

In FIG. 3, the receiver 14 is separated by the separating unit 14.
1, a decryption unit 142, and a second key management unit 143. The demultiplexing unit 141 demultiplexes the multiplexed information as needed. The decryption unit 142 uses the key input from the second key management unit 143 to decrypt the encrypted program information.
The decryption algorithm is the encryption unit 121 of the broadcaster 12.
It is a decryption algorithm corresponding to the encryption algorithm used in.

The second key management unit 143, like the first key management unit 123, comprises a key processing unit 41 and a key storage unit 42, as shown in FIG. The key storage unit 42 stores a plurality of keys, and the key processing unit 41 manages generation and deletion of these keys. Further, the key processing unit 41 outputs the accumulated key in response to the request, inputs the key management information for managing the key, and manages and operates the accumulated key.

The second key management unit 143 determines that the unauthorized recipient 1
In order to make the illicit operation by 4 difficult, it is desirable that the tamper resistant medium such as an IC card that is difficult to illicitly operate is used. Further, since it is realized by a tamper-resistant medium, it is possible to automatically execute the key management process by the key management information.

Next, the time transition and the state of each entity will be described with reference to FIG. First, at time A, the second key management unit 143 of the recipient 14 stores only the key Key A in the key storage unit 42. The key Key A is assumed to be stored in advance at the time of contract. In addition, the second key management unit 143
It is realized in a tamper resistant medium such as an IC card, and the receiver 14 cannot freely use the key Key A.

At time B, the broadcasting company 12
The key management unit 123 outputs the key Key A, encrypts the program information Pro A using the key Key A, multiplexes the encrypted program information Pro A and the key management information, and multiplexes the information. To broadcast.

Since the receiver 14 who has received the broadcast has the key Key A stored in the first key management unit 123, it can decrypt the encrypted program information Pro A and can view the program information Pro A. is there. Further, the receiver 14 stores the program information Pro A in the storage 21.

Even at time C, the receiver 14 has stored the key Key A in the key storage unit 42 of the second key management unit 143, and therefore decrypts the encrypted program information ProA stored in the storage 21. However, the program information Pro A can be viewed.

At time D, the broadcaster 12
The key management unit 123 outputs the key Key B, encrypts the program information Pro B using the key Key B, broadcasts the encrypted program information Pro B, and deletes the key Key A and creates the key Key B. Key management information is transmitted.

As the transmission method, there are a method of transmitting by multiplexing with the encrypted program information Pro B and a method of directly transmitting only the key management information to the recipient 14 via the communication medium, but it is not particularly limited. The second of the recipients 14 who received this key management information
The key management unit 143 performs the process of “erasing key Key A and generating key Key B”.

The second key management unit 143 is realized by a tamper-proof medium such as an IC card, and the above-mentioned key management processing is forcibly and automatically performed when the key management information is received. To be executed. As a result, only the key Key A is stored in the key storage unit 42 of the second key management unit 143.

At time E, the key storage unit 42 of the second key management unit 143 of the receiver 14 stores only the key Key B. Therefore, the program information Pro B encrypted with the key Key B can be decrypted and viewed, but the key Key
The program information ProA encrypted by A cannot be decrypted and cannot be viewed.

In the present embodiment, the second key management unit 143
It is characterized by automatic key management by. In particular, by sequentially updating the key to a new key, only the receiver 14 who has the new key can view the program information. Also,
In the present embodiment, in order to simplify the description, one key is focused and described, but each key management unit 123, 143
It is also possible to manage multiple keys at the same time.

That is, as shown in FIG. 10, a plurality of keys such as key Key A and news A, and key Key B and news B are used, and each key is associated with each content or each meta information. It is also possible. When a key is associated with each content, it enables viewing control for each content,
When a key is associated with each piece of meta information, use control for each piece of meta information is possible.

In the present embodiment, the case where the entity that generates encrypted program information or encrypted meta information by using the key and the entity that manages the key and generates the key management information are the same are described. May be different entities. The configuration is shown in FIG.

FIG. 6 is composed of a broadcasting company 12, a meta information providing company 13, and a receiver 14. Broadcaster 1
2. The meta information provider 13 and the receiver 14 both use the key, but only the broadcaster 12 generates the key management information.

The broadcasting company 12 and the receiver 14 are the same as described above. The meta information provider 13 shown in FIG. 6 is an entity that provides meta information, and is the second encryption unit 1.
31 and a third key management unit 132.

The third key management unit 132 manages the key and outputs the key when necessary, and the second encryption unit 131 operates the third key management unit 132.
The meta information is encrypted using the key input from the key management unit 132 and is transmitted to the recipient 14. Third key management unit 1
32 is realized by a tamper resistant medium such as an IC card.

In FIG. 6, regarding the meta information, the broadcaster 12 that is the entity that manages the key and the entity that transmits the encrypted meta information are different. That is, the broadcaster 12 manages the key, thereby enabling the use control of the meta information provided by the meta information provider 13 holding the specific key.

In particular, by using a plurality of keys and associating the keys with the meta information providing business operator 13, it becomes possible to control the use of the meta information provided from a specific meta information providing business operator 13, that is, the meta information. The effectiveness of the information provider 13 can be controlled.

Further, a method of associating the key with the meta-information provider 13 or the broadcaster 12 and a method of associating the content or the meta-information with the key may be combined, but the above-mentioned method is simply combined. If so, the detailed description is omitted.

FIG. 7 shows a block diagram when it is adapted to the conventional receiver limitation system. In FIG. 7, the broadcaster 12
The broadcast device 70 includes a scrambler 71 and a multiplexer 7.
2, a first encryption unit 73, a second encryption unit 74, and a first key management unit 75.

The first key management unit 75 manages the key, and the second key management unit 75
The key is output to the encryption unit 74. Also, the key management information is output to the multiplexing unit 72 as needed.

The second encryption unit 74 has the first key management unit 7
The work key and contract information are encrypted using the key input from 5. The first encryption unit 73 uses the work key to
Encrypt the scramble key. The scrambler 71 is
The program information is scrambled using the scramble key. The multiplexing unit 72 multiplexes the scrambled program information, the encrypted scramble key, the encrypted work key, the encrypted contract information, and the key management information as necessary.

In FIG. 7, the receiver 80 of the receiver 14
Is composed of a separation unit 81, a descramble unit 82, a first decryption unit 83, a second decryption unit 84, a viewing determination unit 85, and a second key management unit 86.

The second key management unit 86 manages the key and
The key is output to the decryption unit 84. When the key management information is input, the key is managed according to the input key management information. The demultiplexing unit 81 is means for performing a process corresponding to the process performed by the multiplexing unit 72 on the broadcasting device 70 side,
Input multiplexing information and separate. The second decoding unit 84
Using the key input from the second key management unit 86, the separation unit 8
The encrypted work key and the encrypted contract information input from 1 are decrypted.

The first decryption unit 83 uses the work key input from the second decryption unit 84 to decrypt the encrypted scramble key input from the separation unit 81. The viewing determination unit 85
The contract information is input from the second decryption unit 84, and the scramble key is input from the first decryption unit 83. Whether the viewing is permitted or not is determined, and the scramble key is output.

The descrambling unit 82 has a viewing determination unit 85.
The scrambled program information is descrambled using the scramble key input from.

In the present embodiment, by automatically updating the key, even if the program information and the contract information are stored in the storage of the receiver 14 as a set, the viewing control can be performed by invalidating the key. to enable. In particular, the automatic key update is realized by transmitting the key control information at the same time as the delivery of a new program.

In the present embodiment, the encryption or scramble process is implemented for the program information, but it is obvious that the meta information can be similarly handled.

Next, another embodiment of the key management unit will be described. In the above-described embodiments, the key management unit is realized by a tamper-proof medium such as an IC card, and the key storage and key management processing is automatically performed. In other words, it is premised that the key holding and key management processes are secure.

However, the safety of the tamper resistant medium is not perfect, and it is necessary to supplement the safety by another method. Therefore, a method for improving the security by using a method based on the common key cryptosystem and a method based on the public key cryptosystem for the key management unit using the cryptographic technique will be described.

Further, regarding distribution of the key management information, a method will be described in which the key management information can be safely provided only to the specific receiver 14 even if a communication medium for an unspecified large number of receivers 14 such as broadcasting is used. To do.

FIG. 8 shows a configuration example of a key management unit based on the common key cryptosystem. First, the common key cryptosystem will be described. The common key cryptosystem is a system in which common information is used as a key, the key is secretly shared by the sender and the receiver, and the message is converted by the sender and the receiver using the key. Since the same key is secretly shared, it is also called secret key cryptosystem, symmetric key cryptosystem, or conventional cryptosystem. DES encryption (Data Encryption Stan
dard), MISTY encryption, AES (Advanced Encryption Standard)
Etc. are known.

In FIG. 8, the first key management unit 810 is
It is composed of a first key selection unit 811, a first key processing unit 812, and a first key storage unit 813.

The second key management section 820 comprises a second key selection section 821, a second key processing section 822, and a second key storage section 823.

The first key storage unit 813 shown in FIG. 8 stores a plurality of keys. Multiple keys are classified into fixed keys and others. Also, the first key selection unit 811 selects a key to be used for encryption processing from the plurality of keys stored in the first key storage unit 813 in response to a request from the encryption unit, and selects the selected key. Output.

The first key processing unit 812 manages the keys stored in the first key storage unit 813. It also generates and outputs key management information for managing the recipient's key. Managing a key is new generation of a key or deletion of a stored key. That is, when the usage control is performed for each content or meta information, a key is generated each time new content is generated, and the generated key is used to encrypt or scramble the content or meta information.

The key management information is stored in the second key storage section 82.
3 is information for realizing generation of a new key and deletion of the stored key, and is composed of an instruction for realizing generation of a key including new key information and an instruction for realizing an erasing operation. To be done.

That is, when content or meta information is newly distributed, it is composed of an instruction for adding a key including a corresponding new key, and when prohibiting the use of content or meta information, it corresponds. It is composed of instructions that realize key deletion. Furthermore, if necessary, the key management information is encrypted using a fixed key.

The second key storage unit 823 shown in FIG. 8 stores a plurality of keys. Multiple keys are classified into fixed keys and others. The second key selection unit 821 selects a key to be used for the decryption processing from the plurality of keys stored in the second key storage unit 823 in response to the request from the decryption unit 142, and outputs the selected key.

The second key processing section 822 manages the keys stored in the second key storage section 823. It also generates a key or deletes the key according to the received key management information. Furthermore, if the received key management information is encrypted, it is decrypted using a fixed key.

That is, when the usage control is performed for each content or meta information, a command for generating a secret key including a new key is received for each new content or meta information, and a new key is stored in the second storage unit. Each time it generates, stores, and prohibits the use of content or meta information, it receives an instruction to delete the corresponding key, and deletes the corresponding key from the second storage unit.

The key management section based on the common key cryptosystem encrypts the key management information with the fixed key even if the key management information is multiplexed with the program information and is transmitted to an unspecified number of recipients. By doing so, it becomes possible to safely transmit to a specific user. As a result, it is possible to prevent fraud such as eavesdropping on a new key transmitted to another recipient 14 and adding it as a new key.

FIG. 9 shows a configuration example of a key management unit based on the public key cryptosystem. First, the public key cryptosystem will be described. The public key cryptosystem is a cryptosystem in which the key to be encrypted is different from the key to be decrypted, and one of them can be made public. The public key is called the public key and the other is called the private key, and the private key is kept secret.

The public key and the private key have a one-to-one correspondence, and the message converted by the public key can be decrypted only by the corresponding private key. Furthermore, it is designed so that the private key cannot be known from the public key. In addition, a digital signature that identifies the signer of the message can be realized by performing the encryption and decryption processes using the public key cryptosystem in reverse.

That is, a specific signer who owns the private key converts a message with the private key to generate a signature, and an unspecified number of signature verifiers who can own the public key perform verification using the public key. Known public key cryptosystems include RSA cryptography and ElGamal cryptography.

A system using the public key cryptosystem is a certificate authority (hereinafter referred to as CA), a certificate, and a certificate revocation list.
It is often used under a public key infrastructure (hereinafter referred to as PKI) that uses (hereinafter referred to as CRL). The legitimacy of the public key is assured by using the certificate for the user's public key created by the CA and the public key together. In addition, by referring to the CRL during the certificate verification process, it is possible to check whether the certificate has been revoked.

In FIG. 9, the broadcasting company 12 realizes the CA function, and the first key management unit 910 includes a first key selection unit 911, a first key processing unit 912, and a first key. Accumulator 9
It is composed of 13.

The second key management section 920 comprises a second key selection section 921, a second key processing section 922, and a second key storage section 923.

The first key storage unit 913 shown in FIG. 9 stores a secret key corresponding to the broadcaster, a plurality of public keys, and a CRL. The public key is associated with the broadcaster, the meta information provider, and the receiver. The CRL is managed by the CA.

The first key selection unit 911 shown in FIG. 9 selects a public key used for encryption processing from a plurality of public keys stored in the first key storage unit 913 in response to a request from the encryption unit. Select and output the selected public key.

Further, the first key processing unit 912 manages the keys and CRLs stored in the first key storage unit 913. It also generates and outputs key management information for managing the recipient's key and CRL. The key management information is stored in the second key storage unit 923.
This is the information for erasing the key stored in, the addition of a new key, and the update of the CRL, and is composed of an instruction for implementing the erasing operation, new key information, and CRL update information.
If necessary, the public key is used to encrypt the key management information, and the private key is used to generate a digital signature for the key management information.

The second key storage unit 923 shown in FIG. 9 stores the secret key corresponding to the recipient 14, a plurality of public keys, and the CRL. Also, the second key selection unit 921 outputs the secret key stored in the second key storage unit 923 in response to the request from the decryption unit 142.

Further, the second key selection unit 921 has the decryption unit 1
In response to the request of 42, the secret key stored in the second key storage unit 923 is output when the validity is confirmed by CRL. In addition, the second key processing unit 922
Manages the private key and the CRL stored in the key storage unit 923. It also generates a private key, deletes the private key, and updates the CRL according to the received key management information.

In particular, when the received key management information is encrypted, it is decrypted using the private key, and when it has a digital signature, the validity of the public key by CRL and the validity of the digital signature are verified. , If it is valid, the key management process is performed.

The key management unit based on the public key cryptosystem is similar to the key management unit based on the common key cryptosystem.
Even if the key management information is multiplexed with the program information and the key management information is transmitted to an unspecified number of recipients, it can be safely transmitted to a specific user by encrypting with the secret key.

Also, the validity check of the key based on the CRL can be realized at the same time, and a simpler key management can be realized as compared with the common key cryptosystem-based key management system.

(Other Embodiments of the Present Invention) The present invention may be applied to a system including a plurality of devices or an apparatus including a single device.

Further, in order to operate various devices so as to realize the functions of the above-described embodiment, a computer in an apparatus or system connected to the various devices may be operated from a storage medium or the Internet. A program code of software for realizing the functions of the above-described embodiments is supplied via a transmission medium, and a computer (CPU or M) of the system or apparatus is supplied.
What was carried out by operating the above-mentioned various devices according to the program stored in PU) is also contained in the category of the present invention.

Further, in this case, the program code itself of the software realizes the functions of the above-described embodiments, and the program code itself and means for supplying the program code to the computer, for example, such program. The storage medium storing the code constitutes the present invention. A storage medium for storing the program code is, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-R.
An OM, a magnetic tape, a non-volatile memory card, a ROM or the like can be used.

Further, the computer executes the supplied program code so that not only the functions described in the above embodiments are realized, but also the OS (operating system) in which the program code is operating in the computer. Needless to say, the program code is also included in the embodiments of the present invention when the functions shown in the above embodiments are implemented jointly by other application software or the like.

Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the function expansion board or function expansion unit is instructed based on the instruction of the program code. The present invention also includes a case where the CPU or the like included in the above performs some or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

[0110]

As described above, according to the present invention, the problems described above can be solved, and viewing control can be performed even for program information or meta information accumulated in the storage in server type broadcasting. A digital system that can be reliably performed can be provided.

Further, according to another feature of the present invention, it is possible to provide a system in which already realized programs are compatible with existing systems including BS digital broadcasting which is a distribution system.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention and showing an outline of a digital broadcasting system.

FIG. 2 is a configuration diagram showing a basic configuration of a conditional access system according to an embodiment of the present invention.

FIG. 3 is a configuration diagram showing an outline of a digital broadcasting system in the present embodiment.

FIG. 4 is a diagram showing a configuration example of a key management unit in the present embodiment.

FIG. 5 is a diagram showing a state with respect to time regarding a broadcaster and a receiver in the present embodiment.

FIG. 6 is a diagram showing a second embodiment of the present invention and showing a schematic configuration of a digital broadcasting system.

FIG. 7 is a configuration diagram showing an embodiment in which the present invention is applied to a receiver limitation system.

FIG. 8 is a diagram showing a second configuration example of the key management unit of the present embodiment.

FIG. 9 is a diagram showing a third configuration example of the key management unit of the present embodiment.

FIG. 10 is a diagram showing correspondence between keys and contents in the present embodiment.

FIG. 11 is a configuration diagram showing a configuration of a conventional recipient limitation method.

[Explanation of symbols]

11 Administrator 12 Broadcasters 13 Meta information providers 14 recipients 21 storage 31 Communication medium 121 Encryption unit 122 Multiplexer 123 First key management unit 141 Separation part 142 Decoding unit 143 Second key management unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04N 7/167 H04N 5/91 L H04L 9/00 601B F term (reference) 5C025 BA25 BA30 DA01 DA04 DA10 5C053 FA20 GB06 GB40 LA14 5C064 BA01 BB02 BC07 BC17 BC22 BC25 BD03 BD08 BD09 CA18 CB01 CB05 CC02 5J104 AA16 EA04 EA09 EA18 EA19 PA05 (54) [Invention name] Digital content processing device, digital broadcasting receiving device, digital content processing system, digital broadcasting System, digital content processing method, computer-readable storage medium, and computer program

Claims (24)

[Claims] 1. A digital content processing device for handling digital content and meta information about the digital content, the second content being input after holding first control information for controlling the digital content or the meta information. Management means for managing the held first control information according to the control information, and control means for controlling the use of the digital content or the meta information according to the first control information. Digital content processing device. 2. The digital content processing apparatus according to claim 1, wherein the first control information is an encryption key in a common key cryptosystem. 3. The digital content processing apparatus according to claim 2, wherein the management unit manages the first control information by deleting the encryption key. 4. The digital content processing apparatus according to claim 2, wherein the management unit manages the first control information by updating the encryption key. 5. The digital content processing apparatus according to claim 1, wherein the first control information is a decryption key in a public key cryptosystem. 6. The digital content processing apparatus according to claim 5, wherein the management unit manages the first control information by an invalidation list in the public key cryptosystem. 7. The digital content processing apparatus according to claim 1, wherein the first control information is associated with the digital content or the meta information. 8. The digital content processing according to claim 1, wherein the first control information is associated with a distributor of the digital content or the meta information. apparatus. 9. The digital content processing according to claim 1, wherein the management unit that manages the first control information is realized by a medium that is difficult to tamper with. apparatus. 10. A digital broadcast receiving apparatus, characterized in that the digital content processing apparatus according to any one of claims 1 to 9 is used to handle broadcast content which is the digital content. 11. A digital content processing system, comprising the digital content processing device according to claim 1. Description: 12. A digital broadcasting system comprising the digital content processing device according to claim 1. Description: 13. A digital content processing method for handling digital content and meta information about the digital content, wherein first control information for controlling the digital content or the meta information is held in a medium and input. Second
And a control step of controlling the use of the digital content or the meta information by the first control information. Digital content processing method. 14. The first control information is an encryption key in a common key cryptosystem.
The digital content processing method described in. 15. The digital content processing method according to claim 14, wherein the managing step manages the first control information by deleting the encryption key. 16. The digital content processing method according to claim 14, wherein the managing step manages the first control information by updating the encryption key. 17. The digital content processing method according to claim 13, wherein the first control information is a decryption key in a public key cryptosystem. 18. The digital content processing method according to claim 17, wherein the managing step manages the first control information by an invalidation list in the public key cryptosystem. 19. The digital content processing method according to claim 13, wherein the first control information is associated with the digital content or the meta information. 20. The digital content processing according to claim 13, wherein the first control information is associated with a distributor of the digital content or the meta information. Method. 21. The digital content processing method according to claim 13, wherein the medium that holds the first control information is realized by a medium that is difficult to tamper with. . 22. A computer-readable storage medium on which a program for causing a computer to function as each unit according to any one of claims 1 to 9 is recorded. 23. A computer-readable storage medium having recorded thereon a program for causing a computer to execute the digital content processing method according to any one of claims 13 to 21. 24. A computer program for causing a computer to execute the digital content processing method according to any one of claims 13 to 21.