JP2020178185A - Content distribution device, mobile terminal, receiving device, and program thereof - Google Patents

Abstract

To provide a system that allows a user to enjoy the same broadcasting services as the user does at a house even outside the house.SOLUTION: A home broadcast service enjoyment system S includes an encryption Kwt generation server 4 that generates an encryption Kwt on the basis of usage attribute obtained by sending a temporal work key (Kwt) that encrypts a scrambled key from a receiving device 7, a private key generation server 5 that generates a private key on the basis of the usage attribute sent from a mobile terminal 6, a mobile terminal 6 that sends the usage attribute to the private key generation server 5, receives the private key, and sends the private key to the receiving device 7, and the receiving device 7 that receives the encryption Kwt by sending the usage attribute to the server 4 and decrypts the encryption Kwt with the private key received from the mobile terminal 6 to obtain the encryption Kwt that decrypts the scrambled key.SELECTED DRAWING: Figure 2

Description

The present invention relates to a content distribution device, a mobile terminal, a receiving device, and a program thereof capable of viewing encrypted broadcast contents under the same conditions inside and outside the home.

Currently, the broadcasting service employs a triple key method of scramble key (Ks), work key (Kw), and master key (Km), and broadcasts by encrypting (scrambled) the broadcast content (hereinafter referred to as content). ..
Specifically, as shown in FIG. 15, the broadcasting station has encrypted content in which the content is encrypted with the scramble key (decryption key) Ks and encryption in which the scramble key (Ks) is encrypted with the work key (Kw). The encrypted scramble key and the encrypted work key in which the work key (Kw) is encrypted with the master key (Km) common to the receiving device are multiplexed and distributed. A scramble key is a key that is updated in a few seconds. The work key is a key that is renewed in about one month to one year. The master key is a key unique to the receiving device.
On the other hand, the receiving device decrypts the encrypted work key into the work key (Kw) using the master key (Km), and decrypts the encrypted scramble key into the scramble key (Ks) using the work key (Kw). Then, the receiving device decrypts the encrypted content into the content by using the scramble key (Ks).

In order to enjoy this broadcasting service, the receiving device has a built-in mechanism for generating (decrypting) the scramble key. This mechanism is built into the B-CAS card for satellite broadcasting and terrestrial broadcasting, and in the IC chip embedded in the receiving device for 4K8K satellite broadcasting, and decrypts the content without the B-CAS card or IC chip. Is not possible. Further, in pay broadcasting, contract information is stored in the B-CAS card or IC chip, and the output of the scramble key from the B-CAS card or IC chip is controlled based on the contract information.

If the B-CAS card or IC chip can be taken out, it is possible to enjoy the same broadcasting service as that enjoyed at home, for example, even outside the home.
However, it is very difficult to take out the IC chip. Further, although it is possible to take out the B-CAS card, the structure is such that it is difficult for the receiving device to take out the card in consideration of damage to the device and the card. In addition, there are several types of cards these days, and one card is not compatible with all receiving devices. Furthermore, if a family member uses one B-CAS card and takes it out, the family members other than the person who took it out will not be able to enjoy the broadcasting service at home.

On the other hand, a method has been proposed in which the unauthorized user tracking code is modified to set a time limit so that the same broadcasting service as in the home can be enjoyed outside the home (hereinafter, OHI07 method; see Non-Patent Document 1). Furthermore, various devices (IoT [Internet of Things] devices, etc.) can be connected to the broadcast receiving device by the broadcast communication cooperation service that integrates broadcasting and communication. For example, a broadcast communication cooperation service called Hybridcast (registered trademark) has been started in September 2013 (see Non-Patent Documents 2 and 3). A method of enjoying the same broadcasting service outside the home as in the home by setting time limits and location restrictions using the cooperation between the IoT device and the broadcast receiving device and the Attribute-Based Encryption (ABE) method. Has been proposed (hereinafter, OTH17 method; see Non-Patent Document 4).

K. Ogawa, G. Hanaoka, and H. Imai, “Traitor Tracing Scheme Secure against Key Exposure and its Application to Anywhere TV service,” IEICE Trans. On Fundamentals, Vol.E90-A, no.5, pp.1000- 1011, 2007. "Broadcasting Communication Cooperation System Specification (IPTVFJ STD-0010) 2.2 Edition", IPTV Forum, Revised on September 21, 2018 "HTML5 Browser Specification (IPTVFJ STD-0011) 2.4 Edition", General Incorporated Association IPTV Forum, revised on September 21, 2018 K. Ogawa, S. Tamura, and G. Hanaoka, “Key Management for Versatile Pay-TV services,” Proc. Of International Workshop on Security and Trust Management 2017, pp.3-18, 2017.

In the conventional OHI07 method, the same broadcasting service as in the home can be enjoyed outside the home with a time limit, but the place where the broadcasting service can be enjoyed cannot be restricted. Therefore, as a form of service, it is desired to set not only a time limit but also a limit based on usage conditions such as a place.
Further, in the conventional OTH17 method, although the time and place to be used outside the home can be limited, since ABE, which is a public key cryptosystem that requires heavy calculation, is used, encryption and decryption related to ABE are performed. The terminal that performs processing has a large load, and it is desired to reduce the load.

The present invention has been made in view of such a problem, and the same broadcasting service as in the home can be enjoyed even outside the home under predetermined usage conditions without taking out the B-CAS card or the IC chip. At the same time, it is an object of the present invention to provide a content distribution device, a mobile terminal, a receiving device, and a program thereof, which are additionally required for light encryption and decryption processing.

In order to solve the above problems, the content distribution device according to the present invention is a content distribution device that encrypts content and distributes it to a receiving device, and includes a content encryption means, a first scramble key encryption means, and a second. The configuration includes a scramble key encryption means, a work key encryption means, a multiplexing means, a stream transmission means, and a second work key transmission means.

In such a configuration, the content distribution device encrypts the content with a scramble key by the content encryption means to generate the encrypted content.
Further, the content distribution device encrypts the scramble key with the first work key by the first scramble key encryption means to generate the first encrypted scramble key. Further, the content distribution device encrypts the scramble key with the second work key by the second scramble key encryption means to generate the second encrypted scramble key.
As a result, the scrambled key is encrypted with two different work keys.
Further, the content distribution device encrypts the first work key with the master key of each receiving device by the work key encryption means to generate the first encrypted work key.
Then, the content distribution device multiplexes the encrypted content, the first encrypted scramble key, the second encrypted scramble key, and the first encrypted work key by the multiplexing means.
Then, the content distribution device transmits the stream data multiplexed by the multiplexing means to the receiving device by the stream transmitting means. As a result, the first work key is multiplexed with the encrypted content and broadcast as in the conventional case.

Further, the content distribution device transmits the second work key to the server that performs the calculation of the encryption function by the second work key transmitting means.
This encryption function uses the hash value of the usage attribute information including the user's authentication token and the place and time to view the content, and uses the common key encryption method to convert the second work key to the second encrypted work key. It is a function to calculate.
This allows the server to generate a second encrypted work key.
The content distribution device can be operated by a program for operating the computer as each of the above-mentioned means.

Further, in order to solve the above-mentioned problems, the mobile terminal according to the present invention uses a private key for decrypting the second encrypted work key that encrypts the second work key used for encrypting the scramble key of the content. The mobile terminal to be generated is configured to include a usage attribute information transmitting means, a private key receiving means, and a private key information transmitting means.

In such a configuration, the mobile terminal transmits the usage attribute information including the user's authentication token and the place and time for viewing the content to the server that performs the calculation of the private key generation function by the usage attribute information transmitting means.
This secret key generation function is a function that converts the hash value of the usage attribute information into a secret key having a key length predetermined by the common key cryptosystem to be used.

In addition, the mobile terminal receives the private key from the server by the private key receiving means.
Then, the mobile terminal transmits the authentication token and the private key as the private key information to the receiving device for viewing the content by the private key information transmitting means.
The mobile terminal can be operated by a program for operating the computer as each of the above-mentioned means.

Further, in order to solve the above problems, the receiving device according to the present invention scrambles the encrypted content in which the content is encrypted with the scramble key, the first encrypted scramble key in which the scramble key is encrypted with the first work key, and the scrambled key. Content is generated from stream data in which the second encrypted scramble key in which the key is encrypted with the second work key and the first encrypted work key in which the first work key is encrypted with the master key of each receiver is multiplexed. A receiving device for decrypting, the first work key decryption means, the first scramble key decryption means, the usage attribute information transmission means, the second encrypted work key receiving means, the private key information receiving means, and the second. The configuration includes a work key decryption means, a second scramble key decryption means, a switching means, and a content decryption means.

In such a configuration, the receiving device decrypts the first encrypted work key multiplexed on the stream data into the first work key with the master key by the first work key decryption means. Further, the receiving device decrypts the first encrypted scramble key multiplexed on the stream data by using the first work key by the first scramble key decryption means into the scramble key.
In addition, the receiving device transmits the usage attribute information to the server that calculates the encryption function using the usage attribute information including the user's authentication token and the place and time for viewing the content by the usage attribute information transmitting means. Send.
This encryption function is a function that calculates the second encrypted work key from the second work key by the common key cryptosystem using the hash value of the usage attribute information.
Further, the receiving device receives the second encrypted work key from the server by the second encrypted work key receiving means.
As a result, the receiving device can acquire the second encrypted work key.

Further, the receiving device receives the authentication token and the private key as the private key information from the mobile terminal by the private key information receiving means.
Then, the receiving device decrypts the second encrypted work key into the second work key by the second work key decryption means using the private key.
Further, the receiving device decrypts the second encrypted scramble key multiplexed on the stream data by using the second work key by the second scramble key decryption means into the scramble key.
Further, the receiving device switches and outputs the scrambled key decrypted by the first scrambled key decoding means and the scrambled key decrypted by the second scrambled key decoding means by the switching means.
Then, the receiving device decrypts the encrypted content multiplexed into the stream data by using the scramble key output from the switching means by the content decrypting means.

Further, in order to solve the above problems, the receiving device according to the present invention scrambles the encrypted content in which the content is encrypted with the scramble key, the first encrypted scramble key in which the scramble key is encrypted with the first work key, and the scrambled key. Content is generated from stream data in which the second encrypted scramble key in which the key is encrypted with the second work key and the first encrypted work key in which the first work key is encrypted with the master key of each receiver is multiplexed. A receiving device for decrypting, which is a first work key decryption means, a usage attribute information transmitting means, a second encrypted work key receiving means, a private key information receiving means, a second work key decrypting means, and a switching means. , And a scramble key decryption means and a content decryption means.

In such a configuration, the receiving device decrypts the first encrypted work key multiplexed on the stream data into the first work key with the master key by the first work key decryption means.
In addition, the receiving device transmits the usage attribute information to the server that calculates the encryption function using the usage attribute information including the user's authentication token and the place and time for viewing the content by the usage attribute information transmitting means. Send.
This encryption function is a function that calculates the second encrypted work key from the second work key by the common key cryptosystem using the hash value of the usage attribute information.
Further, the receiving device receives the second encrypted work key from the server by the second encrypted work key receiving means.
As a result, the receiving device can acquire the second encrypted work key.

Further, the receiving device receives the authentication token and the private key as the private key information from the mobile terminal by the private key information receiving means.
Then, the receiving device decrypts the second encrypted work key into the second work key by the second work key decryption means using the private key.
Further, the receiving device was decrypted by the first work key decrypted by the first work key decrypting means, the first encrypted scramble key multiplexed with the stream data, and the second work key decrypting means by the switching means. The second work key and the second encrypted scramble key multiplexed on the stream data are switched and output.
Further, the receiving device uses the scramble key decryption means to decrypt the first encrypted scramble key into the scramble key using the first work key, or decrypts the first encrypted scramble key into the scramble key using the second work key, based on the output of the switching means. 2 Decrypt the encrypted scramble key into a scramble key.
Then, the receiving device decrypts the encrypted content multiplexed into the stream data by using the scramble key by the content decryption means.
The receiving device can be operated by a program for operating the computer as each of the above-mentioned means.

The present invention has the following excellent effects.
According to the present invention, a user of a broadcasting service can enjoy the same contents as those enjoyed by a home receiving device at a receiving device on the go without removing a B-CAS card or an IC chip from the receiving device. can do.
Further, according to the present invention, the encryption function is configured by the hash function and the common key cryptosystem, and the load of encryption and decryption can be lightened.

It is explanatory drawing for demonstrating the outline of the processing of the home broadcasting service enjoyment system which concerns on embodiment of this invention. It is a system block diagram which shows the whole structure of the home broadcasting service enjoyment system which concerns on embodiment of this invention. It is a block diagram which shows the structure of the content distribution apparatus of FIG. It is a block diagram which shows the structure of the authentication apparatus of FIG. It is a block diagram which shows the structure of the encryption Kwt generation server of FIG. It is a block diagram which shows the structure of the private key generation server of FIG. It is a block diagram which shows the structure of the mobile terminal of FIG. It is a block diagram which shows the structure of the receiving device of FIG. It is a flowchart which shows the operation which transfers the temporal work key (Kwt) of the home broadcasting service enjoyment system which concerns on embodiment of this invention to an encrypted Kwt generation server. It is a flowchart which shows the operation of acquiring a private key in the mobile terminal of the home broadcasting service enjoyment system which concerns on embodiment of this invention. It is a flowchart which shows the operation of decoding a temporal work key (Kwt) in the receiving device of the home broadcasting service enjoyment system which concerns on embodiment of this invention. It is a flowchart which shows the operation of decoding the content in the receiving device of the home broadcasting service enjoyment system which concerns on embodiment of this invention. It is explanatory drawing for demonstrating other processing of the home broadcasting service enjoyment system which concerns on embodiment of this invention. It is a block diagram which shows the other configuration of the receiving device of FIG. It is explanatory drawing for demonstrating the processing content of the triple key system in the conventional broadcasting service.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[About the processing of the home broadcasting service enjoyment system]
First, with reference to FIG. 1, the outline of the processing of the home-use broadcasting service enjoyment system S will be described. The out-of-home broadcasting service enjoyment system S is a system for viewing content that can be viewed under a contract on a receiving device (reception device 7 on the go) other than the receiving device for which the user has a viewing contract.

Broadcasting station 1 encrypts the content and broadcasts it by broadcasting waves. Here, the broadcasting station 1 encrypts the content by the conventional triple key (scramble key [Ks], work key [Kw], master key [Km]) method, and Ks has a shorter update period than Kw ( For example, one day) It is encrypted with a temporal work key (hereinafter, Kwt), multiplexed with encrypted content, and broadcast. That is, the broadcasting station 1 individually encrypts Ks with Kw (first work key) and Kwt (second work key), and duplicates the encrypted scramble key for broadcasting.
Further, the broadcasting station 1 transmits Kwt to the encrypted Kwt generation server 4.

The encryption Kwt generation server 4 calculates a function (encryption function) for encrypting Kwt and generates an encryption temporal work key (hereinafter, encryption Kwt). The function that encrypts this Kwt is the same function as the function that generates the private key using a hash function such as SHA-3 (Secure Hash Algorithm 3) on the private key generation server 5 described later, and the output of that function. A composite of a common key encryption such as AES (Advanced Encryption Standard) that encrypts Kwt as an encryption key can be used as one function.
Here, the encryption Kwt generation server 4 calculates the encryption function data from the Kwt received from the broadcasting station 1 and the usage attribute (installation location, current time) and the authentication token received from the receiving device 7 described later. Generate encrypted Kwt (Ckwt).

The secret key generation server 5 calculates a function (secret key generation function) that generates a secret key (skt) that decrypts the encrypted Kwt, and generates the secret key. A hash function such as SHA-3 can be used as the function for generating this private key.
Here, the secret key generation server 5 generates a secret key from the usage attributes (use location, usage time) and authentication token received from the mobile terminal 6 by data calculation of the secret key generation function.

The mobile terminal 6 stores the private key for decrypting the encrypted Kwt and outputs it to the receiving device 7.
Here, the mobile terminal 6 transmits the usage attribute (usage location, usage time) and the authentication token to the private key generation server 5. The authentication token is a token unique to a user who has a contract to view pre-authenticated content with an authentication device (not shown).
Then, the mobile terminal 6 acquires the private key from the private key generation server 5, stores it, and outputs it to the receiving device 7 when viewing the content.

The receiving device 7 on the go decrypts the encrypted content broadcast from the broadcasting station 1 by the triple key method. Here, when a user who has a contract other than the receiving device 7 uses the receiving device 7, the user transmits the private key and the authentication token to the receiving device 7 by the mobile terminal 6. The receiving device 7 receives the private key and the authentication token from the mobile terminal 6, and transmits the usage attribute (installation location, current time) and the authentication token to the encrypted Kwt generation server 4. The installation location indicates the location (latitude, longitude, etc.) where the receiving device 7 is installed, and the current time indicates the current date.

Then, the receiving device 7 acquires the encrypted Kwt from the encrypted Kwt generation server 4.
At this time, if the usage attribute set in the mobile terminal 6 and the usage attribute set in the receiving device 7 are the same, the acquired encrypted Kwt is decrypted with the private key (skt) acquired from the mobile terminal 6. can do.
Then, the receiving device 7 can decrypt the encrypted scramble key into the scramble key with Kwt, and can decrypt the content with the scramble key.
That is, outside the home broadcast service receiving system S is realized by calculating a function f ₁ of the common key encryption system showing generation of encryption Kwt, the following equation (1).

Here, AES_Enc indicates an encryption function that calculates AES. H indicates a function that matches the output (hash value) of SHA-3 with the key length of AES, and “||” indicates the concatenation of each element. Here, matching the output of SHA-3 with the key length of AES means converting the 512-bit output of SHA-3 into 128 bits, which is the same as the key length of AES. For example, the first 128 bits of the SHA-3 output are used, or the SHA-3 output is divided into 4 bits and the XOR value is used for each, so that the SHA-3 output is AES. Can be matched to the key length of.
Further, px and py indicate the installation location (latitude, longitude, etc.) of the receiving device 7 among the usage attributes, tp indicates the current time (year / month / day) of the usage attributes, and α indicates an authentication token. β indicates the secret information of the encrypted Kwt generation server 4 and the private key generation server 5.
The order of px, py, tp, α and β in the function H of the equation (1) may be any order, but the px, py, tp, α and β of the function H of the equation (2) described later may be used. The order is the same as the order of.
The out-of-home broadcasting service enjoyment system S can generate an encrypted Kwt by calculating the encryption function of the equation (1), which is composed of only a light operation such as a common key encryption method and a hash function.
Also, out-of-home broadcast service receiving system S is realized by calculating a function f ₂ showing the generation of a secret key, the following equation (2).

Here, H indicates a function (secret key generation function) that generates a secret key by matching the output (hash value) of SHA-3 with the key length of AES, and “||” indicates the concatenation of each element. Further, px and py indicate the place of use (latitude, longitude, etc.) of the receiving device 7 that uses the service of the usage attributes, and tp indicates the usage time (year / month / day) of using the service of the usage attributes. , Α indicates an authentication token. β indicates the secret information of the encrypted Kwt generation server 4 and the private key generation server 5.
The out-of-home broadcasting service enjoyment system S can restore the private key for decrypting the encrypted Kwt by calculating the private key generation function of the equation (2).
Note that β of equations (1) and (2) is necessary to enhance the security of key generation by using each server (encryption Kwt generation server 4, secret key generation server 5) in this service. However, in the present invention, it is not always necessary to set it.
Hereinafter, the configuration and operation of the home broadcasting service enjoyment system S will be described.

[Configuration of out-of-home broadcasting service enjoyment system]
The configuration of the home-use broadcasting service enjoyment system S will be described with reference to FIG.
As shown in FIG. 2, the home-use broadcasting service enjoyment system S includes a content distribution device 2, an authentication device 3, an encrypted Kwt generation server 4, a private key generation server 5, a mobile terminal 6, and a receiving device 7. And.

The content distribution device 2 and the authentication device 3 are devices provided in the broadcasting station 1 (broadcasting company). Further, the authentication device 3, the encryption Kwt generation server 4, the private key generation server 5, the mobile terminal 6, and the receiving device 7 are connected by a network (here, the Internet N).
Hereinafter, the configuration of each device will be described with reference to the drawings.

(Content distribution device)
The configuration of the content distribution device 2 will be described with reference to FIG. 3 (see FIG. 2 as appropriate).
The content distribution device 2 encrypts content (broadcast content such as video and audio) and distributes the encrypted content by broadcast wave W via a transmission device (not shown).
As shown in FIG. 3, the content distribution device 2 includes a content encryption means 20, a first Ks encryption means 21, a second Ks encryption means 22, a Kw encryption means 23, a multiplexing means 24, and a stream. A transmission means 25 and a Kwt transmission means 26 are provided.

The content encryption means 20 encrypts contents such as video and audio with Ks (scramble key). Ks is an encryption key that is updated in a few seconds.
The content encryption means 20 outputs the encrypted content (encrypted content) to the multiplexing means 24.

The first Ks encryption means (first scramble key encryption means) 21 encrypts Ks that encrypts the content with Kw (work key). Kw is an encryption key that is updated by a broadcaster in about one to several months.
The first Ks encryption means 21 outputs Ks (first encryption Ks: Cks) encrypted with Kw to the multiplexing means 24.

The second Ks encryption means (second scramble key encryption means) 22 encrypts Ks that encrypts the content with Kwt (temporal work key). Kwt is an encryption key that is updated in about one day depending on the broadcaster. The Kwt is not limited to each broadcaster, and may be a different encryption key for each channel, each program, and the like.
The second Ks encryption means 22 outputs Ks (second encryption Ks: Ckst) encrypted with Kwt to the multiplexing means 24.

The Kw encryption means (work key encryption means) 23 encrypts Kw used when encrypting Ks by the first Ks encryption means 21 with Km (master key). Km is an individual encryption key in the receiving device 7.
The Kw encryption means 23 outputs the encrypted Kw (encryption Kw) to the multiplexing means 24.

The multiplexing means 24 multiplexes the encrypted content, the first encrypted Ks, the second encrypted Ks, and the encrypted Kw. The multiplexing means 24 outputs the stream data generated by multiplexing to the stream transmitting means 25.

The stream transmission means 25 transmits the stream data generated by the multiplexing means 24 to a transmission device (not shown). This stream data will be distributed to the receiving device 7 by the transmitting device via the broadcast wave W.

The Kwt transmitting means 26 transmits Kwt used when encrypting Ks by the second Ks encryption means 22 to the encrypted Kwt generation server 4.
The Kwt transmission means 26 transmits Kwt to the encrypted Kwt generation server 4 via a network such as the Internet N.

By configuring the content distribution device 2 as described above, the content distribution device 2 can individually encrypt Ks with Kw and Kwt and duplicate them. Further, the content distribution device 2 can distribute Kwt by a route different from that of the broadcast wave W.
The content distribution device 2 can be operated by a program for operating the computer as each of the above-mentioned means.

(Authentication device)
The configuration of the authentication device 3 will be described with reference to FIG. 4 (see FIG. 2 as appropriate).
The authentication device 3 authenticates whether or not the user has a contract with the broadcasting station 1 to view the content.
As shown in FIG. 4, the authentication device 3 includes an authentication token request receiving means 30, an authentication means 31, a user information storage means 32, and an authentication token transmitting means 33.

The authentication token request receiving means 30 receives an authentication token request including a user identifier that identifies a user from the mobile terminal 6 via the Internet N.
The authentication token request receiving means 30 outputs the received authentication token request to the authentication means 31.

The authentication means 31 uses the user identifier included in the authentication token request to determine whether or not the user has a contract with broadcasting station 1 (broadcasting company), and more specifically, the user views the content outside the home. Authenticate whether or not the service is contracted at the user's home.
The authentication means 31 authenticates whether or not the user corresponding to the user identifier has a contract for a service for viewing the content outside the home, based on the user information stored in the user information storage means 32. To do.
Then, when the user corresponding to the user identifier is the contractor of the service as the authentication result, the authentication means 31 generates an authentication token and outputs the authentication token to the authentication token transmission means 33. As this authentication token generation method, a general software token generation method can be used. In addition, the authentication means 31 performs password authentication as to whether or not the authentication token request is a request from a legitimate user.

The user information storage means 32 stores the presence or absence of a contract for each user. The user information storage means 32 can be configured by a general storage device such as a hard disk.
In the user information storage means 32, at the stage when the user makes a contract in advance, a user identifier, a password, etc. that individually identify the user are registered as user information via an input means (not shown). Keep it.

The authentication token transmitting means 33 transmits the authentication token generated by the authentication means 31 to the mobile terminal 6 requesting the authentication token via the Internet N.
By configuring the authentication device 3 as described above, the authentication device 3 can authenticate that the user has a contract for a service for viewing contents outside the home.
The authentication device 3 can be operated by a program for operating the computer as each of the above-mentioned means.

(Encrypted Kwt generation server)
The configuration of the encrypted Kwt generation server 4 will be described with reference to FIG. 5 (see FIG. 2 as appropriate).
The encrypted Kwt generation server 4 uses the Kwt transmitted from the content distribution device 2 and the usage attribute information (usage attribute, authentication token) transmitted from the receiving device 7 described later to encrypt the Kwt. It is what you generate.
As shown in FIG. 5, the encrypted Kwt generation server 4 includes a Kwt receiving means 40, a Kwt storage means 41, a usage attribute information receiving means 42, an encrypted Kwt calculation means 43, and an encrypted Kwt transmitting means 44. , Equipped with.

The Kwt receiving means 40 receives Kwt from the content distribution device 2 via the Internet N.
The Kwt receiving means 40 stores the received Kwt in the Kwt storage means 41.
The Kwt storage means 41 stores Kwt received by the Kwt receiving means 40. The Kwt storage means 41 can be configured by a general storage device such as a hard disk.

The usage attribute information receiving means 42 receives the usage attribute and the authentication token as the usage attribute information from the receiving device 7 via the Internet N.
The usage attribute information receiving means 42 outputs the received usage attribute and the authentication token to the encrypted Kwt calculation means 43.

The encrypted Kwt calculation means 43 generates the encrypted Kwt by performing data calculation from the Kwt stored in the Kwt storage means 41 and the usage attribute and the authentication token received by the usage attribute information receiving means 42. It is a thing.
The function (Kwt encryption function) that performs the calculation by the encrypted Kwt calculation means 43 is the above-mentioned equation (1). Equation (1) is a combination of a hash function and common key encryption, and is about 1/1000 lighter than ABE encryption.
The encrypted Kwt calculation means 43 outputs the encrypted Kwt, which is the calculation result, to the encrypted Kwt transmitting means 44.

The encrypted Kwt transmitting means 44 transmits the encrypted Kwt generated by the encrypted Kwt calculation means 43 to the receiving device 7 via the Internet N.
By configuring the encrypted Kwt generation server 4 as described above, the encrypted Kwt generation server 4 can generate the encrypted Kwt with a light process.
The encrypted Kwt generation server 4 can be operated by a program for operating the computer as each of the above-mentioned means.

(Private key generation server)
The configuration of the private key generation server 5 will be described with reference to FIG. 6 (see FIG. 2 as appropriate).
The private key generation server 5 generates a private key from the usage attribute information (usage attribute, authentication token) generated by the mobile terminal 6.
As shown in FIG. 6, the secret key generation server 5 includes a usage attribute information receiving means 50, a secret key calculation means 51, and a secret key transmitting means 52.

The usage attribute information receiving means 50 receives the usage attribute and the authentication token as usage attribute information from the mobile terminal 6 via the Internet N.
The usage attribute information receiving means 50 outputs the received usage attribute and the authentication token to the private key calculation means 51.

The private key calculation means 51 generates a secret key by performing data calculation from the usage attribute and the authentication token received by the usage attribute information receiving means 50.
The function (secret key generation function) that is calculated by the secret key calculation means 51 is the above-mentioned equation (2). Equation (2) is a combination of a hash function and a simple operation for matching its output to the key length of the common key cryptosystem, and is about 1/1000 lighter than ABE's secret key generation.
The private key calculation means 51 outputs the secret key, which is the calculation result, to the secret key transmission means 52.

The private key transmitting means 52 transmits the private key generated by the private key calculating means 51 to the mobile terminal 6 via the Internet N.
By configuring the private key generation server 5 as described above, the private key generation server 5 can generate the private key with a light process.
The private key generation server 5 can be operated by a program for operating the computer as each of the above-mentioned means.

(Mobile terminal)
The configuration of the mobile terminal 6 will be described with reference to FIG. 7 (see FIG. 2 as appropriate).
The mobile terminal 6 holds and carries a private key for decrypting encrypted contents so that the contents contracted by the user can be viewed on the receiving device 7 on the go.
As shown in FIG. 7, the mobile terminal 6 includes an authentication token request transmitting means 60, an authentication token receiving means 61, a storage means 62, a usage attribute input means 63, a usage attribute information transmitting means 64, and a private key reception. The means 65 and the private key information transmitting means 66 are provided.

The authentication token request transmission means 60 transmits an authentication token request including a user identifier that identifies a user to the authentication device 3 via the Internet N.
The authentication token request transmitting means 60 transmits the user identifier obtained by making a contract with the broadcasting company in advance to the authentication device 3. The contract shall include a service for the user to view the content outside the home.
The authentication token request transmitting means 60 authenticates the user with the authentication device 3 by using a password or the like entered by the user via an input means (not shown).

The authentication token receiving means 61 receives the authentication token from the authentication device 3 via the Internet N as a response to the authentication token request requested by the authentication token request transmitting means 60. The authentication token receiving means 61 stores the received authentication token in the storage means 62.

The storage means 62 stores the data acquired by the mobile terminal 6. The storage means 62 can be configured by a general storage device such as a hard disk.
The storage means 62 stores the authentication token received by the authentication token receiving means 61 and the private key received by the secret key receiving means 65 described later.

The usage attribute input means 63 inputs usage attributes for viewing the content on the receiving device 7 on the go.
Specifically, the usage attribute is the usage location and usage time of the receiving device 7 that uses the service for viewing the content.
The place of use may be any information as long as the place can be specified as a numerical value, and is, for example, latitude, longitude, or XY coordinates projected on a plane of the earth. Here, the place of use is expressed as px, py. In addition, the usage attribute input means 63 does not directly input the usage location as a numerical value, but incorporates general software for inputting an address and converting it into numerical values such as latitude and longitude for conversion.
The usage time is the date when the content is viewed. Here, the usage time is expressed as tp.
The usage attribute input means 63 outputs the input usage location px, py and usage time tp to the usage attribute information transmitting means 64.

The usage attribute information transmitting means 64 uses the usage attribute input by the usage attribute input means 63 and the authentication token received by the authentication token receiving means 61 and stored in the storage means 62 as the usage attribute information, and is used as the secret key generation server 5. It is to be sent to. The usage attribute information transmitting means 64 transmits the usage attribute information (usage attribute and authentication token) to the private key generation server 5 via the Internet N.

The private key receiving means 65 receives the private key from the private key generation server 5 via the Internet N.
The private key receiving means 65 stores the received private key skt in the storage means 62.

The private key information transmitting means 66 transmits the authentication token and the private key stored in the storage means 62 to the receiving device 7 at the destination as the private key information.
The private key information transmitting means 66 transmits the authentication token and the private key to the receiving device 7 when the user is instructed to transmit the information in the receiving device 7 on the go. The data transmission between the mobile terminal 6 and the receiving device 7 is not particularly limited, but infrared communication may be used, or a hybrid cast connect or the like specified in Non-Patent Documents 2 and 3 may be used. ..

By configuring the mobile terminal 6 as described above, the mobile terminal 6 can carry a private key for decrypting the encrypted content so that the content can be viewed on the receiving device 7 on the go.
The mobile terminal 6 can be operated by a program for operating the computer as each of the above-mentioned means.

(Receiver)
The configuration of the receiving device 7 will be described with reference to FIG. 8 (see FIG. 2 as appropriate).
The receiving device 7 receives and decrypts the encrypted content distributed from the broadcasting station 1.
As shown in FIG. 8, the receiving device 7 includes a location information storage means 70, a timing means 71, a private key information receiving means 72, a usage attribute information transmitting means 73, an encrypted Kwt receiving means 74, and a Kwt decryption. The means 75, the second Ks decoding means 76, the stream receiving means 77, the separation means 78, the Kw decoding means 79, the first Ks decoding means 80, the switching means 81, and the content decoding means 82 are provided.

The location information storage means 70 stores in advance the location where the receiving device 7 is installed. As the location information storage means 70, a general storage medium such as a semiconductor memory can be used.
The location where the receiving device 7 is installed may be any information as long as it can be specified as a numerical value, but information in the same format as the usage location to be input to the usage attribute input means 63 described with reference to FIG. 7 (here, px, Notated as py).
The timekeeping means 71 is a timer that measures the time. The timekeeping means 71 also clocks the date (here, referred to as tp) as the current time.
The private key information receiving means 72 receives the private key and the authentication token as the private key information from the mobile terminal 6.
The private key information receiving means 72 outputs the received authentication token to the usage attribute information transmitting means 73. Further, the private key information receiving means 72 outputs the received private key to the Kwt decoding means 75.

The usage attribute information transmitting means 73 receives the usage attribute consisting of the location information (installation location) stored in the location information storage means 70, the current time measured by the timing means 71, and the private key information receiving means 72. The authenticated authentication token is transmitted to the encrypted Kwt generation server 4 as usage attribute information.
The usage attribute information transmitting means 73 acquires the location information (installation location) from the location information storage means 70 and the current time from the timing means 71 at the timing when the authentication token is input from the private key information receiving means 72. The usage attribute (installation location, current time) and the authentication token are transmitted to the encrypted Kwt generation server 4 via the Internet N.

The encrypted Kwt receiving means (second encrypted work key receiving means) 74 receives the encrypted Kwt from the encrypted Kwt generation server 4 via the Internet N.
The encrypted Kwt receiving means 74 outputs the received encrypted Kwt to the Kwt decrypting means 75.

The Kwt decryption means (second work key decryption means) 75 decrypts the encrypted Kwt (CkWt) received by the encrypted Kwt receiving means 74 by using the secret key skt received by the secret key information receiving means 72. is there.
The Kwt decoding means 75 outputs the temporal work key (Kwt) obtained by decrypting the encrypted Kwt (Ckwt) to the second Ks decoding means 76.

The second Ks decryption means (second scramble key decryption means) 76 uses the Kwt decrypted by the Kwt decryption means 75 to scramble the second encrypted Ks (Ckst) separated by the separation means 78 described later. It is decrypted to Ks).
The second Ks decoding means 76 outputs the decoded Ks to the switching means 81.

The stream receiving means 77 receives the stream data distributed from the content distribution device 2 via the broadcast wave W.
The stream receiving means 77 outputs the received stream data to the separating means 78.

The separating means 78 separates the stream data received by the stream receiving means 77 into individual data.
The separation means 78 separates the encrypted content from the stream data and outputs it to the content decryption means 82. Further, the separation means 78 separates the encrypted Kw (Ckw) from the stream data and outputs it to the Kw decryption means 79. Further, the separation means 78 separates the first encrypted Ks (Cks) from the stream data and outputs the first encrypted Ks (Cks) to the first Ks decoding means 80. Further, the separation means 78 separates the second encrypted Ks (Ckst) from the stream data and outputs the second encrypted Ks (Ckst) to the second Ks decoding means 76.

The Kw decryption means (first work key decryption means) 79 decrypts the encrypted Kw (Ckw) separated by the separation means 78 by using the master key (Km) unique to the receiving device 7.
The Kw decoding means 79 outputs the decrypted work key (Kw) to the first Ks decoding means 80.

The first Ks decryption means (first scramble key decryption means) 80 decrypts the first encrypted Ks (Cks) separated by the separation means 78 by using the work key (Kw) decrypted by the Kw decryption means 79. It is a thing.
The first Ks decoding means 80 outputs the decrypted scramble key (Ks) to the switching means 81.
The Kw decoding means 79 and the first Ks decoding means 80 are built in the B-CAS card or the IC chip.

The switching means 81 switches between the Ks decoded by the first Ks decoding means 80 and the Ks decoded by the second Ks decoding means 76 and outputs the Ks to the content decoding means 82.
The switching means 81 switches to input the output from the first Ks decoding means 80 when viewing the content contracted by the receiving device 7. Further, the switching means 81 is switched so that the output from the second Ks decoding means 76 is input when the user views the content as the receiving device 7 on the go by the mobile terminal 6.
The input of the switching means 81 can be switched by, for example, an external switch or the like.

The content decryption means 82 decrypts the encrypted content separated by the separation means 78 by using the scramble key (Ks) switched by the switching means 81.
The content decoding means 82 presents the decoded content to the user via a display means (not shown).

By configuring the receiving device 7 as described above, the receiving device 7 can decrypt the temporal work key (Kwt) using the private key received from the mobile terminal 6. As a result, the user can view the content on the receiving device 7 on the go without making a contract.
The receiving device 7 can be operated by a program for operating the computer as each of the above-mentioned means.

[Operation of out-of-home broadcasting service enjoyment system]
The operation of the home-use broadcasting service enjoyment system S will be described with reference to FIGS. 9 to 12.
(Preparatory operation to generate encrypted Kwt)
The operation of passing the Kwt of the home broadcasting service enjoyment system S to the encrypted Kwt generation server 4 will be described with reference to FIG. 9 (see FIGS. 3 and 5 as appropriate for the configuration).

First, the content distribution device 2 performs the following operations in steps S1 to S7.
In step S1, the first Ks encryption means 21 encrypts Ks (scramble key) with Kw (work key).
In step S2, the second Ks encryption means 22 encrypts Ks with Kwt (temporal work key).
In step S3, the Kw encryption means 23 encrypts Kw with the master key (Km).
In step S4, the content encryption means 20 encrypts the content with Ks.

In step S5, the multiplexing means 24 is encrypted in step S1 with Ks (first encryption Ks), Ks encrypted in step S2 (second encryption Ks), and step S3. The Kw (encrypted Kw) and the encrypted content generated in step S4 are multiplexed.
In step S6, the stream transmission means 25 transmits the stream data multiplexed in step S5 to a transmission device (not shown) and transmits to the reception device 7.
Further, in step S7, the Kwt transmitting means 26 transmits Kwt to the encrypted Kwt generation server 4 separately from the path for encrypting and multiplexing Kwt and transmitting the stream.

Then, the encrypted Kwt generation server 4 performs the operations of the following steps S8 and S9.
In step S8, the Kwt receiving means 40 receives Kwt from the content distribution device 2.
In step S9, the Kwt receiving means 40 stores the Kwt received in step S8 in the Kwt storage means 41.
By the above operation, Kwt is stored in the encrypted Kwt generation server 4.

(Mobile terminal acquires private key)
The operation of the mobile terminal 6 acquiring the private key for decrypting the encrypted Kwt of the home broadcasting service enjoyment system S will be described with reference to FIG. 10 (see FIGS. 4, 6 and 7 for the configuration as appropriate). ..

In step S10, the authentication token request transmitting means 60 of the mobile terminal 6 transmits an authentication token request including a user identifier that identifies the user to the authentication device 3. At this time, the user password is added to the authentication token request. In addition, it is preferable to add a hash value after inputting the password into an internal function such as a hash function to the authentication token request instead of the password from the viewpoint of ensuring the security of the password.

Then, the authentication device 3 performs the following operations of steps S11 to S13.
In step S11, the authentication token request receiving means 30 receives the authentication token request from the mobile terminal 6.
In step S12, the authentication means 31 subscribes to a service in which a user stored in the user information storage means 32 in advance uses the user identifier and password included in the authentication token request to view the content outside the home. Authenticate whether or not.
Here, the authentication means 31 generates an authentication token only when the user has a contract for a service for viewing the content outside the home.
In step S13, the authentication token transmitting means 33 transmits the authentication token generated in step S12 to the mobile terminal 6 that requested the authentication token.

Then, the mobile terminal 6 performs the following operations of steps S14 to S17.
In step S14, the authentication token receiving means 61 receives the authentication token from the authentication device 3.
In step S15, the authentication token receiving means 61 stores the authentication token received in step S14 in the storage means 62.
In step S16, the usage attribute input means 63 inputs the usage location px, py, and usage time tp of the receiving device 7 that uses the service for viewing the content.
In step S17, the usage attribute information transmitting means 64 generates a secret key for the usage attribute consisting of the usage location px, py and the usage time tp input in step S16 and the authentication token α stored in the storage means 62. Send to server 5.

After that, the private key generation server 5 performs the operations of the following steps S18 to S20.
In step S18, the usage attribute information receiving means 50 receives the usage attribute and the authentication token from the mobile terminal 6.
In step S19, the secret key calculation means 51 generates a secret key from the usage attribute and the authentication token received in step S18 by data calculation by the secret key generation function of the above equation (2).
In step S20, the private key transmitting means 52 transmits the private key generated in step S19 to the mobile terminal 6.

Then, the mobile terminal 6 performs the following operations of steps S21 and S22.
In step S21, the private key receiving means 65 receives the private key from the private key generation server 5.
In step S22, the private key receiving means 65 stores the private key received in step S21 in the storage means 62.
By the above operation, the mobile terminal 6 can acquire the private key.

(The operation of the receiving device to decode Kwt)
The operation of the receiving device 7 decoding Kwt in the home broadcasting service enjoyment system S will be described with reference to FIG. 11 (see FIGS. 5, 7, and 8 for the configuration as appropriate).
In step S30, the private key information transmitting means 66 of the mobile terminal 6 transmits the private key skt and the authentication token α to the receiving device 7 at the destination.

Then, the receiving device 7 performs the following operations in steps S31 to S33.
In step S31, the private key information receiving means 72 receives the private key skt and the authentication token α from the mobile terminal 6.
In step S32, the usage attribute information transmitting means 73 acquires the installation location px and py stored in the location information storage means 70, and also acquires the current time tp from the timing means 71.
In step S33, the usage attribute information transmitting means 73 transmits the usage attribute consisting of the installation location and the current time acquired in step S32 and the authentication token received in step S31 to the encrypted Kwt generation server 4.

After that, the encrypted Kwt generation server 4 performs the operations of the following steps S34 to S36.
In step S34, the usage attribute information receiving means 42 receives the usage attribute and the authentication token from the receiving device 7.
In step S35, the encryption Kwt calculation means 43 calculates data from the usage attribute and the authentication token received in step S34 and the Kwt stored in the Kwt storage means 41 by the encryption function of the above equation (1). , Generate encrypted Kwt.
In step S36, the encrypted Kwt transmitting means 44 transmits the encrypted Kwt generated in step S35 to the receiving device 7.

Then, the receiving device 7 performs the following operations in steps S37 and S38.
In step S37, the encrypted Kwt receiving means 74 receives the encrypted Kwt from the encrypted Kwt generation server 4.
In step S38, the Kwt decryption means 75 decrypts the encrypted Kwt received in step S37 into Kwt using the private key received in step S31.
By the above operation, the receiving device 7 can generate Kwt with the encrypted Kwt generated by the encrypted Kwt generation server 4 and the private key acquired from the mobile terminal 6.

(The operation of the receiving device to decrypt the content)
The operation of the receiving device 7 decoding the content in the home-use broadcasting service enjoyment system S will be described with reference to FIG. 12 (see FIGS. 3 and 8 as appropriate for the configuration). Since the decoding of the content in the receiving device 7 in the user's home is the same as in the conventional case, only the operation of decoding the content in the receiving device 7 on the go outside the user's home will be described here. That is, it is assumed that the switching means 81 is switched so as to input the output from the second Ks decoding means 76.

In step S40, the stream transmission means 25 of the content distribution device 2 transmits the stream data. Note that this step S40 is the same as step S6 described with reference to FIG.

Then, the receiving device 7 performs the following operations of steps S41 to S44.
In step S41, the stream receiving means 77 receives the stream data from the content distribution device 2.
In step S42, the separation means 78 uses the stream data received in step S41 as individual data (encrypted Kw [Ckw], first encrypted Ks [Cks], second encrypted Ks [Ckst], and encrypted content. ).
In step S43, the second Ks decryption means 76 decrypts the second encrypted Ks (Ckst) separated in step S42 into the scramble key (Ks) by using the Kwt decrypted in step S38 of FIG.
In step S44, the content decryption means 82 decrypts the encrypted content separated in step S42 by using the scramble key decrypted in step S43.

By the above operation, the receiving device 7 can decrypt the scramble key with the temporal work key (Kwt). As a result, even a user who does not have a contract with the receiving device 7 can view the content with the receiving device 7 on the go if he / she has a contract to view the content outside the home.

Although the configuration and operation of the home broadcasting service enjoyment system S have been described above, the present invention is not limited to this embodiment.
Here, the home-use broadcasting service enjoyment system S uses AES for encryption of the temporal work key (Kwt). However, as the Kwt encryption method, if it is a common key cryptosystem, an encryption function other than AES, for example, Camellia, KCipher-2, or the like may be used.
Further, although SHA-3 is used here for generating the secret key for AES, a hash function other than SHA-3, for example, SHA-2 or the like may be used.

Further, here, as shown in FIG. 1, the receiving device 7 decrypts Cks (first encrypted Ks) with Kw (first work key), Ks (scramble key), and Ckst (second encryption). It was decided to switch the Ks) with the Ks decrypted with the Kwt (second work key) to decrypt the encrypted content.
However, as shown in FIG. 13, the receiving device 7 may be a receiving device 7B that decodes Ks after switching between Cks and Ckst and switching between Kw and Kwt in conjunction with each other.

The configuration of the receiving device 7B will be described with reference to FIG. 14 (see FIG. 2 as appropriate).
The receiving device 7B receives and decrypts the encrypted content distributed from the broadcasting station 1.
As shown in FIG. 14, the receiving device 7B includes a location information storage means 70, a timing means 71, a private key information receiving means 72, a usage attribute information transmitting means 73, an encrypted Kwt receiving means 74, and a Kwt decryption. The means 75, the stream receiving means 77, the separating means 78, the Kw decoding means 79, the content decoding means 82, the switching means 83, and the Ks decoding means 84 are provided.
That is, the receiving device 7B is configured to include the switching means 83 and the Ks decoding means 84 in place of the second Ks decoding means 76, the first Ks decoding means 80, and the switching means 81 of the receiving device 7 (FIG. 8).
Since the configurations other than the switching means 83 and the Ks decoding means 84 are the same as the configurations of the receiving device 7 described with reference to FIG. 8, the description thereof will be omitted.

The switching means 83 switches between Kwt decrypted by the Kwt decoding means 75 and Kw decrypted by the Kw decoding means 79, and the second encryption Ks (Ckst) and the first encryption Ks separated by the separation means 78. Switching to (Cks) is performed in conjunction with the output to the Ks decoding means 84.
When viewing the content contracted by the receiving device 7B, the switching means 83 decrypts the Kw decrypted by the Kw decoding means 79 and the first encrypted Ks (Cks) separated by the separating means 78. Switch to output to means 84. Further, in the switching means 83, when the user views the content as the receiving device 7B on the go by the mobile terminal 6, the Kwt decrypted by the Kwt decoding means 75 and the second encrypted Ks separated by the separating means 78 ( Ckst) is switched to output to the Ks decoding means 84.
The input of the switching means 83 can be switched by, for example, an external switch or the like.

The Ks decryption means (scramble key decryption means) 84 uses the first encryption Ks (Cks) or the second encryption Ks (Ckst) switched by the switching means 83, and Kw or Kwt also switched by the switching means 83. It is used to decrypt the scramble key (Ks).
By switching the switching means 83, the Ks decryption means 84 decrypts the first encrypted Ks (Cks) into Ks using Kw and the second encrypted Ks (Ckst) into Ks using Kwt. ..
The Ks decoding means 84 outputs the decoded Ks to the content decoding means 82.

By configuring the receiving device 7B as described above, the receiving device 7B can decrypt the temporal work key (Kwt) by using the private key received from the mobile terminal 6. As a result, the user can view the content on the receiving device 7B on the go without making a contract.
Further, the receiving device 7B can reduce the load of decoding Ks as compared with the receiving device 7.
The receiving device 7B can be operated by a program for operating the computer as each of the above-mentioned means.

Next, the operation of the receiving device 7B will be described.
Since the operation of the receiving device 7B decoding Kwt is the same as the operation of the receiving device 7 described with reference to FIG. 11, the description thereof will be omitted.
Among the operations in which the receiving device 7B decodes the content, the decoding of the content in the receiving device 7B in the user's home is the same as in the conventional case.
Further, the operation of the receiving device 7B decoding the content in the receiving device 7B on the go outside the user's home is different only in the operation subject of step S43 during the operation of the receiving device 7 described with reference to FIG. However, in the switching means 83, the Kwt decrypted by the Kwt decoding means 75 and the second encrypted Ks (Ckst) separated by the separating means 78 are switched so as to be input to the Ks decoding means 84. And.
In step S43, the Ks decryption means 84 decrypts the second encrypted Ks (Ckst) separated in step S42 into the scramble key (Ks) by using the Kwt decrypted in step S38 of FIG.
Other operations are the same as the operations described with reference to FIG.

By the above operation, the receiving device 7B can decrypt the scramble key with the temporal work key (Kwt) as in the receiving device 7. As a result, even a user who does not have a contract with the receiving device 7B can view the content with the receiving device 7B on the go as long as he / she has a contract to view the content outside the home.

S Home broadcasting service enjoyment system 1 Broadcasting station 2 Content distribution device 20 Content encryption means 21 1st Ks encryption means (1st scramble key encryption means)
22 2nd Ks encryption means (2nd scramble key encryption means)
23 Kw encryption means (work key encryption means)
24 Multiplexing means 25 Stream transmitting means 26 Kwt transmitting means 3 Authentication device 30 Authentication token requesting means 31 Authentication means 32 User information storage means 33 Authentication token transmitting means 4 Encryption Kwt generating server 40 Kwt receiving means 41 Kwt storage means 42 Use Attribute information receiving means 43 Encrypted Kwt calculation means 44 Encrypted Kwt transmitting means 5 Private key generation server 50 Usage attribute information receiving means 51 Secret key calculation means 52 Secret key transmitting means 6 Mobile terminal 60 Authentication token request transmitting means 61 Authentication token receiving Means 62 Storage means 63 Usage attribute input means 64 Usage attribute information transmission means 65 Private key information transmission means 66 Secret key information transmission means 7, 7B Receiving device 70 Location information storage means 71 Timing means 72 Secret key information reception means 73 Usage attribute information transmission Means 74 Encrypted Kwt receiving means (second encrypted work key receiving means)
75 Kwt decryption means (second work key decryption means)
76 2nd Ks Decryption Means (2nd Scramble Key Decryption Means)
77 Stream receiving means 78 Separation means 79 Kw decoding means (first work key decoding means)
80 1st Ks Decryption Means (1st Scramble Key Decryption Means)
81 Switching means 82 Content decoding means 83 Switching means 84 Ks decoding means (scramble key decoding means)

Claims (7)

A content distribution device that encrypts content and distributes it to the receiving device.
A content encryption means that encrypts the content with a scramble key to generate encrypted content,
A first scramble key encryption means that encrypts the scramble key with the first work key to generate a first encryption scramble key, and
A second scramble key encryption means that encrypts the scramble key with the second work key to generate a second encryption scramble key, and
A work key encryption means that generates a first encrypted work key by encrypting the first work key with a master key of each receiving device.
A multiplexing means for multiplexing the encrypted content, the first encrypted scramble key, the second encrypted scramble key, and the first encrypted work key.
A stream transmission means for transmitting stream data multiplexed by the multiplexing means to the receiving device, and
An operation of an encryption function that encrypts the second work key into the second encrypted work key is performed using the hash value of the usage attribute information including the user's authentication token and the place and time for viewing the content. A second work key transmitting means for transmitting the second work key to the server,
A content distribution device characterized by being equipped with. A program for causing a computer to function as the content distribution device according to claim 1. A mobile terminal that generates a private key for decrypting a second encrypted work key that encrypts a second work key used for encrypting a content scramble key.
The usage attribute information is transmitted to a server that calculates a secret key generation function that calculates a secret key using a hash value of usage attribute information including a user's authentication token and a place and time for viewing the content. Usage attribute information transmission means and
A private key receiving means for receiving the private key from the server,
A secret key information transmitting means for transmitting the authentication token and the private key as private key information to a receiving device for viewing the content.
A mobile terminal characterized by being equipped with. A program for causing a computer to function as the mobile terminal according to claim 3. The encrypted content in which the content is encrypted with the scramble key, the first encrypted scramble key in which the scramble key is encrypted with the first work key, and the second encryption scramble in which the scramble key is encrypted with the second work key. A receiving device that decrypts the content from stream data obtained by multiplexing a key and a first encrypted work key in which the first work key is encrypted with a master key of each receiving device.
A first work key decryption means for decrypting the first encrypted work key multiplexed on the stream data into the first work key with the master key.
A first scramble key decryption means for decrypting a first encrypted scramble key multiplexed on the stream data using the first work key into the scramble key.
An encryption function that encrypts the second work key into the second encrypted work key is calculated using the hash value of the usage attribute information including the user's authentication token and the place and time for viewing the content. A usage attribute information transmission means for transmitting the usage attribute information to the server,
A second encrypted work key receiving means for receiving the second encrypted work key from the server, and
A private key information receiving means for receiving the authentication token and the private key as private key information from the mobile terminal according to claim 3.
A second work key decryption means for decrypting the second encrypted work key into the second work key using the private key,
A second scramble key decryption means for decrypting the second encrypted scramble key multiplexed on the stream data using the second work key into the scramble key.
A switching means for switching and outputting a scrambled key decrypted by the first scrambled key decoding means and a scrambled key decrypted by the second scrambled key decoding means, and
A content decryption means that decrypts the encrypted content multiplexed on the stream data using the scramble key output from the switching means, and
A receiving device characterized by comprising. The encrypted content in which the content is encrypted with the scramble key, the first encrypted scramble key in which the scramble key is encrypted with the first work key, and the second encryption scramble in which the scramble key is encrypted with the second work key. A receiving device that decrypts the content from stream data obtained by multiplexing a key and a first encrypted work key in which the first work key is encrypted with a master key of each receiving device.
A first work key decryption means for decrypting the first encrypted work key multiplexed on the stream data into the first work key with the master key.
An encryption function that encrypts the second work key into the second encrypted work key is calculated using the hash value of the usage attribute information including the user's authentication token and the place and time for viewing the content. A usage attribute information transmission means for transmitting the usage attribute information to the server,
A second encrypted work key receiving means for receiving the second encrypted work key from the server, and
A private key information receiving means for receiving the authentication token and the private key as private key information from the mobile terminal according to claim 3.
A second work key decryption means for decrypting the second encrypted work key into the second work key using the private key,
The first work key decrypted by the first work key decryption means, the first encryption scramble key multiplexed on the stream data, the second work key decrypted by the second work key decryption means, and the stream. A switching means for switching and outputting the second encrypted scramble key multiplexed on the data, and
Based on the output of the switching means, the first work key is used to decrypt the first encrypted scramble key into the scramble key, or the second work key is used to obtain the second encrypted scramble key. The scramble key decryption means for decrypting to the scramble key,
A content decryption means for decrypting encrypted content multiplexed on the stream data using the scramble key, and
A receiving device characterized by comprising. A program for causing a computer to function as the receiving device according to claim 5 or 6.

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