JP7671588B2 - Benefit acquisition data issuing device, benefit acquisition device, benefit issuing device, and programs thereof - Google Patents

Description

The present invention relates to a bonus acquisition data issuing device, a bonus acquisition device, a bonus issuing device, and programs therefor.

In recent years, advances in digital broadcasting technology have made it possible to provide services that give users rewards such as electronic coupons in return for viewing a program (see, for example, Patent Document 1).
The technology described in Patent Document 1 is a method in which an information processing device acquires rights information (data for acquiring a privilege) for obtaining a privilege from data broadcasting on a broadcast channel, and acquires the privilege based on the rights information at a store or the like of a service provider that provides the privilege.
The rights information is encrypted by a broadcasting station and distributed as a data broadcast. The encrypted rights information is then decrypted by an information processing device using key information for decrypting the rights information. The information processing device then presents the decrypted rights information to a store to obtain a special offer such as an electronic coupon.

International Publication No. 2015/012000

Conventional methods require users to take the trouble of actively acquiring rights information (data for acquiring privileges) through data broadcasting when watching a program. Specifically, users need to operate the data broadcasting screen by pressing the d button (data button) on a remote control to acquire the data broadcasting data.
In addition, since data broadcasting is a broadcast-only function, there is a problem that users who watch programs on the Web (World Wide Web), such as those specified by the World Wide Web Consortium (W3C), cannot use data broadcasting.

The present invention has been made in consideration of the problems with the conventional technology, and aims to provide a bonus acquisition data issuing device, bonus acquisition device, bonus issuing device, and programs for the same that are capable of distributing bonus acquisition data using event metadata contained in a program, regardless of the viewing format of the program, such as broadcast waves or communication.

In order to solve the above-mentioned problems, the bonus acquisition data issuing device of the present invention is a bonus acquisition data issuing device in a bonus distribution system that includes a bonus issuing device that issues bonus information associated with the viewing of a program, a bonus acquisition data issuing device that issues bonus acquisition data for acquiring the bonus information, and a bonus acquisition device that adds an electronic signature to the bonus acquisition data and transmits it to the bonus issuing device to acquire the bonus information , and is configured to include a data encryption means, a signature generation means, and an event metadata transmission means.

In such a configuration, the bonus acquisition data issuing device generates encrypted data by encrypting the bonus acquisition data using a data encryption means with an encryption key corresponding to a decryption key of the fraudulent user tracing encryption method used by the bonus acquisition device. At this time, the data encryption means encrypts individual bonus acquisition data in association with a user's unique identifier. In the fraudulent user tracing encryption method, the decryption key corresponding to the encryption key is different for each user who decrypts the encrypted data. Therefore, even if the decryption key is illegally distributed, it is possible to identify which user distributed it, and illegal distribution of bonus acquisition data can be suppressed.

The privilege acquisition data issuing device then generates, by a signature generating means, a digital signature for the privilege acquisition data using a signature key corresponding to a verification key of a public key cryptosystem used by the privilege acquisition device and the privilege issuing device to verify the digital signature. This digital signature makes it possible to prevent counterfeiting of the privilege acquisition data.

The bonus acquisition data issuing device then transmits, by the event metadata transmitting means, signed encrypted data in which the digital signature generated by the signature generating means has been added to the encrypted data, as event metadata at the time of distribution of the program. At this time, the event metadata transmitting means transmits the individual signed encrypted data as event metadata to the bonus acquisition device corresponding to the user's unique identifier. This event metadata is an event message in the case of broadcasting, or timed metadata in the case of communication, and is data distributed when the program is viewed, so that it can be obtained by the device viewing the program without obtaining data from the data broadcast.
The bonus acquisition data issuing device can be operated by a bonus acquisition data issuing program that causes a computer to function as each of the above-mentioned means.

In order to solve the above problem, the bonus acquisition device according to the present invention is a bonus acquisition device that acquires bonus information associated with viewing a program, and includes an event metadata receiving means, a data decrypting means, a signature verifying means, a bonus acquisition data transmitting means, an encrypted bonus information receiving means, and a bonus information decrypting means.

In such a configuration, the bonus acquisition device receives, from the bonus acquisition data issuing device through the event metadata receiving means, signed encrypted data as event metadata for the program, in which bonus acquisition data for acquiring bonus information is encrypted with an encryption key of the fraudster tracking encryption method, and an electronic signature generated from the bonus acquisition data with a signature key of the public key encryption method is added to the encrypted data.
Since this signed encrypted data is transmitted as event metadata, the privilege acquisition device can acquire the signed encrypted data by viewing the program.
The privilege acquisition device then uses the data decryption means to decrypt the encrypted data into privilege acquisition data using a decryption key corresponding to the encryption key of the fraudster tracing encryption method .
In addition, the bonus acquisition device uses a signature verification means to verify whether or not the electronic signature is a correct electronic signature of the bonus acquisition data decrypted by the data decryption means, using a verification key corresponding to the signature key used by the bonus acquisition data issuing device when generating the electronic signature.

Then, the privilege acquisition device transmits, by the privilege acquisition data transmission means, to the privilege issuing device, signed privilege acquisition data, which is the privilege acquisition data decrypted by the data decryption means and to which the electronic signature verified as correct by the signature verification means has been added.
The privilege acquisition device receives, by the encrypted privilege information receiving means, from the privilege issuing device, the encrypted privilege information obtained by encrypting the privilege information with the encryption key of the fraudulent user tracing encryption method.
The privilege acquisition device then uses the privilege information decryption means to decrypt the encrypted privilege information using the decryption key of the fraudulent user tracing encryption method to generate the privilege information.
This allows the privilege acquisition device to acquire the privilege acquisition data transmitted as event metadata when the program is distributed, and thereby acquire the privilege information.
The bonus acquisition device can be operated by a bonus acquisition program that causes a computer to function as each of the means described above.

In order to solve the above problem, the bonus issuing device according to the present invention is a bonus issuing device that issues bonus information associated with viewing a program, and includes a bonus acquisition data receiving means, a signature verification means, a bonus information encryption means, and an encrypted bonus information transmission means.

In such a configuration, the bonus issuing device receives, via the bonus acquisition data receiving means, signed bonus acquisition data from the bonus acquisition device, in which the bonus acquisition data for acquiring bonus information has been appended with an electronic signature generated by the bonus acquisition data issuing device that issues the bonus acquisition data using a signature key of a public key cryptography system.
Then, the bonus issuing device uses a signature verification means to verify whether the electronic signature is a correct electronic signature for the bonus acquisition data, using a public key cryptography verification key corresponding to the signature key used by the bonus acquisition data issuing device when generating the electronic signature.

Then, when the electronic signature is verified as correct by the signature verification means, the privilege issuing device encrypts the privilege information into encrypted privilege information by the privilege information encryption means with an encryption key corresponding to a decryption key of the fraudulent user tracing encryption method used by the privilege acquisition device .
Then, the privilege issuing device transmits the encrypted privilege information to the privilege acquiring device by means of the encrypted privilege information transmitting means.
This allows the privilege issuing device to provide the encrypted privilege information to the privilege acquisition device that has transmitted the legitimate privilege acquisition data.
The bonus issuing device can be operated by a bonus issuing program that causes a computer to function as each of the above-mentioned means.

The present invention provides the following excellent effects.
According to the present invention, it is possible to distribute special benefit acquisition data by utilizing event metadata contained in a program, regardless of the viewing form of the program, such as broadcast waves or communication.
Furthermore, according to the present invention, the reward acquisition data can be encrypted by a fraud tracing encryption method and a digital signature can be added to the data.
As a result, the present invention can obtain the privilege acquisition data without the trouble of a user having to actively obtain the privilege acquisition data through data broadcasting while watching a program as in the past, and can also suppress the illegal distribution of the privilege acquisition data.

1 is a block diagram showing an overall configuration of a privilege distribution system according to an embodiment of the present invention. 1 is a block diagram showing an internal configuration of a key generating device according to an embodiment of the present invention. 2 is a block diagram showing an internal configuration of a privilege acquisition data issuing device according to an embodiment of the present invention. 1 is a block diagram showing an internal configuration of a privilege acquisition device according to an embodiment of the present invention. 2 is a block diagram showing an internal configuration of a privilege issuing device according to an embodiment of the present invention. FIG. 4 is a sequence diagram showing a key distribution operation of the privilege distribution system according to the embodiment of the present invention. 10 is a sequence diagram showing a distribution operation of the privilege acquisition data of the privilege distribution system according to the embodiment of the present invention. FIG. FIG. 11 is a sequence diagram showing a distribution operation of the privilege acquisition data according to a modified example of the present invention.

<Configuration of the special offer distribution system>
First, with reference to FIG. 1, a configuration of a privilege delivery system 100 according to an embodiment of the present invention will be described.

The privilege distribution system 100 distributes information (hereinafter, referred to as privilege acquisition data) that enables a user who watches a specific program to obtain a privilege.
The privilege acquisition data m is information for acquiring privilege information. The privilege acquisition data m may be any information that identifies privilege information, such as the name of the service provider, the product name, the number of points, the expiration date, etc. The privilege information is a privilege that the user uses, such as points in a point service, an electronic coupon, etc.
The privilege distribution system 100 encrypts and distributes privilege acquisition data m in event metadata (hereinafter referred to as EMD) included in a program broadcast by airwaves or communication (Internet).

As shown in FIG. 1, the privilege distribution system 100 includes a key generating device 1, a privilege acquisition data issuing device 2, a privilege acquisition device 3, and a privilege issuing device 4.
The key generating device 1 generates a key pair (encryption key TTpk, decryption key TTsk) for encrypting or decrypting the privilege acquisition data m, and a key pair (signature key SIGsk, verification key SIGvk) for generating or verifying a signature (digital signature) for the privilege acquisition data m. The key generating device 1 is, for example, a device managed by a key management business operator.

The privilege acquisition data issuing device 2 issues privilege acquisition data m for acquiring privilege information associated with viewing of a program.
The bonus acquisition data issuing device 2 encrypts the bonus acquisition data m into encrypted data c using the encryption key TTpk generated by the key generating device 1, and transmits the encrypted data c as EMD data to the bonus acquisition device 3. The bonus acquisition data issuing device 2 also generates a signature σ for the bonus acquisition data m using the signature key SIGsk generated by the key generating device 1, and transmits the signature σ together with the encrypted data c as EMD data to the bonus acquisition device 3. The bonus acquisition data issuing device 2 is a device managed by a broadcasting company or a communications carrier.
The privilege acquisition data m is added to a specific program according to a contract between a service provider and a broadcasting station.

The privilege acquisition device 3 acquires privilege information associated with viewing of a program.
The privilege acquisition device 3 acquires the EMD attached to a program and distributed, and decrypts the encrypted data c included in the EMD into privilege acquisition data m using the decryption key TTsk generated by the key generation device 1. The privilege acquisition device 3 also verifies the privilege acquisition data m using the verification key SIGvk generated by the key generation device 1 and the signature σ included in the EMD.
The privilege acquisition device 3 transmits the privilege acquisition data m and the signature σ to the privilege issuing device 4, and acquires the encrypted privilege information c' from the privilege issuing device 4. The privilege acquisition device 3 then decrypts the encrypted privilege information c' with the decryption key TTsk generated by the key generating device 1, and acquires the privilege information (e.g., electronic coupon V).
The privilege acquisition device 3 is a device with which a user watches a program via broadcast waves or communication, and is a television receiver, a multi-function terminal, a smartphone, or the like.

The privilege issuing device 4 issues privilege information associated with viewing of a program.
The privilege issuing device 4 acquires the privilege acquisition data m from the privilege acquisition device 3, and issues encrypted privilege information c'.
Here, the privilege issuing device 4 verifies the privilege acquisition data m using the verification key SIGvk generated by the key generating device 1 and the signature σ acquired from the privilege acquisition device 3 together with the privilege acquisition data m.
The privilege issuing device 4 encrypts the privilege information (here, an electronic coupon) using the encryption key TTpk generated by the key generating device 1 to generate encrypted privilege information c′, and transmits the encrypted privilege information c′ to the privilege acquiring device 3 .
In this way, the privilege distribution system 100 enables a user to obtain privilege acquisition data and obtain privilege information simply by viewing a program for which a privilege is available, using the EMD contained in the program broadcast by airwaves or communication.
The configuration of each device will be described below.

<Configuration of the Key Generation Device>
2 (and also FIG. 1 as necessary), a description will be given of the configuration of the key generation device 1. As shown in FIG. 2, the key generation device 1 includes a signature key pair generation means 10, an encryption key pair generation means 11, and a key transmission means 12.

The signature key pair generating means 10 generates a key pair for generating and verifying a signature (digital signature) to be added to data (privilege acquisition data m).
The signature key pair generation means 10 generates, using public key cryptography, a signature key SIGsk, which is secret information to be distributed to a signer (here, a broadcaster), and a verification key SIGvk, which is public information to be distributed to a signature verifier (a user, a service provider), based on predetermined security parameters such as key length.
The public key cryptosystem is not particularly limited, and common systems such as RSA, DSA, and ECDDSA may be used.
The signature key pair generation means 10 outputs the generated key pair (SIGsk, SIGvk) to the key transmission means 12 .

The encryption key pair generating means 11 generates a key pair for encrypting and decrypting data (privilege acquisition data m).
The encryption key pair generation means 11 generates an encryption key TTpk, which is public information to be distributed to a data sender (broadcaster, service provider), and a decryption key TTsk, which is private information to be distributed to a data receiver (user), based on security parameters such as predetermined key length.

The encryption key pair generating means 11 generates the encryption key TTpk and the decryption key TTsk by the Traitor Tracing Encryption (TT encryption) method. The TT encryption method is an encryption method that can generate multiple different decryption keys for one encryption key.
The encryption key pair generating means 11 outputs the generated key pair (TTpk, TTsk) to the key transmitting means 12. Note that the key pair (TTpk, TTsk) is a plurality of key pairs each having the same encryption key TTpk and different decryption keys TTsk.

The key transmitting means 12 transmits the key pair generated by the signature key pair generating means 10 and the key pair generated by the encryption key pair generating means 11 to the bonus acquisition data issuing device 2, the bonus acquisition device 3, and the bonus issuing device 4, respectively.
The key transmitting means 12 transmits the encryption key TTpk and the signature key SIGsk to the privilege acquisition data issuing device 2 via a communication line (not shown).
Furthermore, the key transmitting means 12 transmits the decryption key TTsk and the verification key SIGvk to the privilege acquisition device 3 via a communication line (not shown).

The key sending means 12 sends different decryption keys TTsk to multiple privilege acquisition devices 3 that have requested key sending. At this time, the key sending means 12 stores information (e.g., IP address) that identifies the privilege acquisition device 3 that has made the request in association with the sent decryption key TTsk. This makes it possible to identify the fraudulent user even if the decryption key TTsk is distributed fraudulently.

Furthermore, the key transmitting means 12 transmits the encryption key TTpk and the verification key SIGvk to the privilege issuing device 4 via a communication line (not shown).
Here, the key transmitting means 12 transmits the key information via a communication line, but the key information may be written onto a recording medium such as a CD and distributed by mail or the like.
The key generating device 1 can be operated by a program (key generating program) for causing a computer to function as each of the above-mentioned means.

<Configuration of the privilege acquisition data issuing device>
Next, with reference to Fig. 3 (and with reference to Fig. 1 as necessary), a description will be given of the configuration of the bonus acquisition data issuing device 2. As shown in Fig. 3, the bonus acquisition data issuing device 2 includes a key receiving means 20, a key storage means 21, a data encryption means 22, a signature generating means 23, and an EMD transmitting means 24.

The key receiving means 20 receives the encryption key TTpk and the signature key SIGsk generated by the key generating device 1 .
The key receiving means 20 receives the encryption key TTpk and the signature key SIGsk via a communication line (not shown), and stores them in the key storage means 21 .
The key storage means 21 stores the encryption key TTpk and the signature key SIGsk, and can be configured with a storage medium such as a semiconductor memory.

The data encryption means 22 encrypts the special offer acquisition data with an encryption key of the TT encryption method to generate encrypted data.
The data encryption means 22 inputs the privilege acquisition data m, and encrypts it with the encryption key TTpk stored in the key storage means 21 according to the TT encryption method to generate encrypted data c.
The privilege acquisition data m is added with information (program identification information p) for identifying the program that distributes the privilege acquisition data m. The program identification information p is, for example, a channel, a distribution time, a program name, etc.
The data encryption means 22 outputs the generated encrypted data c and the program specific information p to the EMD transmission means 24 .

The signature generating means 23 generates a signature σ (electronic signature) for the privilege acquisition data m using a signature key of the public key cryptosystem.
The signature generating means 23 calculates a hash value of the privilege acquisition data m using a predetermined hash function, and encrypts the hash value with the signature key SIGsk stored in the key storing means 21 to generate a signature σ.
The signature generating means 23 outputs the generated signature σ to the EMD transmitting means 24 .

The EMD transmission means 24 (event metadata transmission means) transmits signed encrypted data (c, σ) obtained by adding the signature σ generated by the signature generation means 23 to the encrypted data c generated by the data encryption means 22 as event metadata (EMD) when the program is distributed.
The EMD transmission means 24 transmits the program specific information p and the signed encrypted data (c, σ) to a program distribution device (broadcast transmission device or content server) not shown in the figure so that the signed encrypted data (c, σ) is transmitted as EMD at the time of broadcasting (distribution) of the program specified by the program specific information p.

EMD is information included in broadcast waves or communications when a program is distributed. In broadcast waves, EMD corresponds to the event message defined in ARIB TR-B15 by the Association of Radio Industries and Businesses. In communications, EMD corresponds to the timed metadata recommended by the World Wide Web Consortium (W3C).
A program distribution device (broadcast transmitting device or content server) not shown in the figure places the signed encrypted data (c, σ) in the private data area of the EMD and broadcasts (distributes) it when broadcasting (distributing) the program specified by the program specific information p.

This enables the privilege acquisition data issuing device 2 to transmit the signed encrypted data (c, σ) to the privilege acquisition device 3 by using the EMD.
The privilege acquisition data issuing device 2 can be operated by a program (privilege acquisition data issuing program) for causing a computer to function as each of the above-mentioned means.

<Configuration of the Benefit Acquisition Device>
Next, with reference to Fig. 4 (and also with reference to Fig. 1 as necessary), a description will be given of the configuration of the privilege acquisition device 3. As shown in Fig. 4, the privilege acquisition device 3 includes key receiving means 30, key storage means 31, EMD receiving means 32, data decrypting means 33, signature verifying means 34, privilege acquisition data transmitting means 35, encrypted privilege information receiving means 36, and privilege information decrypting means 37.

Note that here, the means for viewing the program in the bonus acquisition device 3, such as means for demodulating or decoding the program, and display means for displaying the program, are general and not directly related to the configuration of the present invention, so illustrations and explanations are omitted.

The key receiving means 30 receives the decryption key TTsk and the verification key SIGvk generated by the key generating device 1 .
The key receiving means 30 receives the decryption key TTsk and the verification key SIGvk via a communication line (not shown), and stores them in the key storage means 31 .
The key storage means 31 stores the decryption key TTsk and the verification key SIGvk, and can be configured with a storage medium such as a semiconductor memory.

The EMD receiving means 32 (event metadata receiving means) receives signed encrypted data (c, σ) distributed in the event metadata (EMD) from the special offer acquisition data issuing device 2.
The EMD receiving means 32 receives an EMD contained in a program distributed via broadcast waves or communication from a broadcast transmitting device or content server not shown in the figure, and extracts the signed encrypted data (c, σ) placed in the private data area of the EMD.
The EMD receiving means 32 outputs the encrypted data c of the received signed encrypted data (c, σ) to the data decrypting means 33. The EMD receiving means 32 also outputs the signature σ of the received signed encrypted data (c, σ) to the signature verifying means 34.

The data decryption means 33 decrypts the encrypted data c of the signed encrypted data (c, σ) received by the EMD receiving means 32 .
The data decryption means 33 decrypts the encrypted data c using the decryption key TTsk stored in the key storage means 31 according to the TT encryption method, thereby generating special benefit acquisition data m.
The data decryption means 33 outputs the generated privilege acquisition data m to the signature verification means 34 .

The signature verification means 34 verifies the signature σ (electronic signature) of the signed encrypted data (c, σ) received by the EMD receiving means 32 .
The signature verification means 34 calculates a hash value of the privilege acquisition data m using the same hash function as the signature generation means 23 (Figure 3), decrypts the signature σ using the verification key SIGvk stored in the key storage means 31, and determines whether the signature σ is a correct signature for the privilege acquisition data m based on whether the decrypted value matches the hash value.

Here, if the signature verification means 34 determines that the signature σ is the signature of the bonus acquisition data m, it outputs signed bonus acquisition data (m, σ) in which the signature σ is added to the bonus acquisition data m to the bonus acquisition data transmission means 35.
If the signature verification means 34 determines that the signature σ is not the signature of the privilege acquisition data m, it ends the process without outputting the signature to the privilege acquisition data transmission means 35 .

The bonus acquisition data transmission means 35 transmits the signed bonus acquisition data (m, σ) that has been verified as a valid signature by the signature verification means 34 to the bonus issuing device 4 via a communication line (not shown).

The bonus acquisition data transmission means 35 does not necessarily need to transmit the signed bonus acquisition data (m, σ) over a communication line. For example, if the bonus acquisition device 3 is configured as a multi-function terminal, a smartphone, or the like, the bonus acquisition data transmission means 35 may display the signed bonus acquisition data (m, σ) as a specific code (e.g., a barcode, a QR code (registered trademark), etc.) on a display screen, and the bonus issuing device 4 may read the code.

The encrypted special offer information receiving means 36 receives the encrypted special offer information c' from the special offer issuing device 4 via a communication line (not shown).
The encrypted special offer information c' is data obtained by encrypting special offer information such as an electronic coupon to be given to a user who has viewed a particular program in the special offer issuing device 4.
The encrypted bonus information receiving means 36 outputs the received encrypted bonus information c′ to the bonus information decrypting means 37 .

In addition, if the user of the bonus acquisition device 3 registers the email address of the bonus acquisition device 3 in advance by user registration or the like, the encrypted bonus information receiving means 36 may receive the encrypted bonus information c' by email.

The special privilege information decryption means 37 decrypts the encrypted special privilege information c′ received by the encrypted special privilege information receiving means 36 .
The bonus information decryption means 37 generates an electronic coupon V by decrypting the encrypted bonus information c′ by the TT encryption method using the decryption key TTsk stored in the key storage means 31 .

As a result, the privilege acquisition device 3 can receive the signed encrypted data (c, σ) via the EMD when a specific program is viewed, and can acquire the encrypted privilege information (electronic coupon V).
The privilege acquisition device 3 can be operated by a program (privilege acquisition program) for causing a computer to function as each of the means described above.

<Configuration of the Benefit Issuing Device>
Next, with reference to Fig. 5 (and also with reference to Fig. 1 as necessary), a description will be given of the configuration of the privilege issuing device 4. As shown in Fig. 5, the privilege issuing device 4 includes a key receiving means 40, a key storage means 41, a privilege acquisition data receiving means 42, a signature verifying means 43, a privilege information encrypting means 44, and an encrypted privilege information transmitting means 45.

The key receiving means 40 receives the encryption key TTpk and the verification key SIGvk generated by the key generating device 1 .
The key receiving means 40 receives the encryption key TTpk and the verification key SIGvk via a communication line (not shown), and stores them in the key storage means 41 .
The key storage means 41 stores the encryption key TTpk and the verification key SIGvk, and can be configured with a storage medium such as a semiconductor memory.

The privilege acquisition data receiving means 42 receives the signed privilege acquisition data (m, σ) from the privilege acquisition device 3 via a communication line (not shown).
Note that the bonus acquisition data receiving means 42 does not necessarily need to receive the signed bonus acquisition data (m, σ) via a communication line. For example, the bonus acquisition data receiving means 42 may be in a form in which the bonus issuing device 4 displays the signed bonus acquisition data (m, σ) as a specific code (e.g., a barcode, a QR code (registered trademark), or the like) on a screen, via a reading device (not shown).

The signature verification means 43 verifies the signature σ (electronic signature) of the signed privilege acquisition data (m, σ) received by the privilege acquisition data receiving means 42 .
The signature verification means 43 calculates a hash value of the privilege acquisition data m using the same hash function as the signature generation means 23 (Figure 3), decrypts the signature σ using the verification key SIGvk stored in the key storage means 41, and determines whether the signature σ is the signature of the privilege acquisition data m based on whether the decrypted value matches the hash value.
The signature verification means 43 outputs the verification result to the bonus information encryption means 44, for example, "1" if the verification is successful and "0" if the verification is unsuccessful.

The special offer information encryption means 44 encrypts the special offer information (electronic coupon V) when the signature verification means 43 verifies that the signature σ is correct.
If the signature σ is verified to be correct, the bonus information encryption means 44 encrypts the electronic coupon V by the TT encryption method with the encryption key TTpk stored in the key storage means 41, thereby generating encrypted bonus information c'.
The bonus information encryption means 44 outputs the generated encrypted bonus information c′ to the encrypted bonus information transmission means 45 .

The encrypted privilege information transmitting means 45 transmits the encrypted privilege information c' generated by the privilege information encrypting means 44 to the privilege acquisition device 3 via a communication line (not shown).
The encrypted privilege information transmitting means 45 transmits the encrypted privilege information c′ to the address of the privilege acquisition device 3 from which the privilege acquisition data receiving means 42 has received the signed privilege acquisition data (m, σ).
Incidentally, by registering the email address of the bonus issuing device 4 in advance in the bonus issuing device 4, the encrypted bonus information sending means 45 may send the encrypted bonus information c' by email.

This enables the privilege issuing device 4 to encrypt privilege information (electronic coupon V) corresponding to the program viewed by the user and transmit it to the privilege obtaining device 3 .
The privilege issuing device 4 can be operated by a program (privilege issuing program) for causing a computer to function as each of the above-mentioned means.

<<Bonus distribution system operation>>
Next, the operation of the privilege distribution system 100 according to the embodiment of the present invention will be described with reference to Fig. 6 and Fig. 7. Here, the operation will be described separately for distributing a key and distributing privilege information.

<Key distribution operation>
First, the key distribution operation of the privilege distribution system 100 will be described with reference to FIG. 6 (for the configuration, see FIGS. 2 to 5).

In step S1, the signature key pair generating means 10 of the key generating device 1 generates a key pair for generating and verifying a signature (digital signature) to be added to data (privilege acquisition data m).
Here, the signature key pair generation means 10 generates, by public key cryptography, a signature key SIGsk to be distributed to a signer (broadcaster) and a verification key SIGvk to be distributed to a signature verifier (user, service provider).

In step S2, the encryption key pair generating means 11 of the key generating device 1 generates a key pair for encrypting and decrypting data (privilege acquisition data m).
Here, the encryption key pair generating means 11 generates an encryption key TTpk to be distributed to a data sender (broadcaster, service provider) and a decryption key TTsk to be distributed to a data recipient (user) using the TT encryption method.
The operation of step S2 may be performed before step S1 or in parallel with step S1.

In step S3, the key transmission means 12 of the key generation device 1 transmits the encryption key TTpk generated in step S2 and the signature key SIGsk generated in step S1 to the bonus acquisition data issuing device 2.

In step S4, the key receiving means 20 of the privilege acquisition data issuing device 2 receives the encryption key TTpk and the signature key SIGsk transmitted in step S3.
In step S5, the key receiving means 20 stores in the key storage means 21 the encryption key TTpk and the signature key SIGsk received in step S4.

In step S6, the key transmission means 12 of the key generation device 1 transmits the decryption key TTsk generated in step S2 and the verification key SIGvk generated in step S1 to the privilege acquisition device 3.

In step S7, the key receiving means 30 of the privilege acquisition device 3 receives the decryption key TTsk and the verification key SIGvk transmitted in step S6.
In step S8, the key receiving means 30 stores in the key storage means 31 the decryption key TTsk and the verification key SIGvk received in step S7.

In step S9, the key transmission means 12 of the key generation device 1 transmits the encryption key TTpk generated in step S2 and the verification key SIGvk generated in step S1 to the bonus issuing device 4.

In step S10, the key receiving means 40 of the privilege issuing device 4 receives the encryption key TTpk and the verification key SIGvk transmitted in step S9.
In step S11, the key receiving means 40 stores in the key storage means 41 the encryption key TTpk and the verification key SIGvk received in step S10.

The operations of steps S3, S6, and S9 may be performed in any order, or may be performed in parallel.
Through the above operations, the key generating device 1 can distribute key information for performing the operation of distributing the bonus information to the bonus acquisition data issuing device 2, the bonus acquisition device 3, and the bonus issuing device 4.

<Bonus Information Distribution Operation>
Next, the operation of delivering bonus information by the bonus delivery system 100 will be described with reference to FIG. 7 (for the configuration, see FIGS. 3 to 5).

First, the privilege acquisition data issuing device 2 performs the following steps S20 to S22.
In step S20, the data encryption means 22 encrypts the privilege acquisition data m input from outside corresponding to the program using the encryption key TTpk stored in the key storage means 21 according to the TT encryption method to generate encrypted data c.
In step S21, the signature generation means 23 calculates a hash value of the bonus acquisition data m using a predetermined hash function, and generates a signature σ (electronic signature) by encrypting the hash value with the signature key SIGsk stored in the key storage means 21.

In step S22, the EMD transmission means 24 transmits the signed encrypted data (c, σ) obtained by adding the signature σ generated in step S21 to the encrypted data c generated in step S20 to the bonus acquisition device 3 as event metadata (EMD) to be distributed during the program broadcast (distribution).

Then, the privilege acquisition device 3 performs the following steps S23 to S27.
In step S23, the EMD receiving means 32 receives the signed encrypted data (c, σ) transmitted by the EMD from the privilege acquisition data issuing device 2 in step S22.
In step S24, the data decryption means 33 decrypts the encrypted data c of the signed encrypted data (c, σ) received in step S23 with the decryption key TTsk stored in the key storage means 31 by the TT encryption method.

In step S25, the signature verification means 34 verifies, using the verification key SIGvk stored in the key storage means 31, whether or not the signature σ (electronic signature) of the signed encrypted data (c, σ) received in step S23 is a correct signature for the bonus acquisition data m decrypted in step S24.

If the signature σ is not a valid signature (No in step S26), the privilege acquisition device 3 ends the operation.
On the other hand, if the signature σ is a valid signature (Yes in step S26), the privilege acquisition data sending means 35 sends the signed privilege acquisition data (m, σ) to the privilege issuing device 4 in step S27.

Then, the privilege issuing device 4 performs the following operations from steps S28 to S32.
In step S28, the privilege acquisition data receiving means 42 receives the signed privilege acquisition data (m, σ) transmitted from the privilege acquisition device 3 in step S27.
In step S29, the signature verification means 43 verifies, using the verification key SIGvk stored in the key storage means 41, whether or not the signature σ of the signed privilege acquisition data (m, σ) received in step S28 is a correct signature for the privilege acquisition data m.

If the signature σ is not a valid signature (No in step S30), the privilege issuing device 4 ends the operation.
On the other hand, if the signature σ is a correct signature (Yes in step S30), in step S31, the bonus information encryption means 44 encrypts the electronic coupon (bonus information) using the encryption key TTpk stored in the key storage means 41 using the TT encryption method to generate encrypted bonus information c'.
In step S32, the encrypted bonus information transmitting means 45 transmits the encrypted bonus information c' generated in step S31 to the bonus acquisition device 3.

Then, the privilege acquisition device 3 performs the following operations of steps S33 and S34.
In step S33, the encrypted bonus information receiving means 36 receives the encrypted bonus information c' transmitted from the bonus issuing device 4 in step S32.
In step S34, the special offer information decryption means 37 decrypts the encrypted special offer information c' received in step S33 using the decryption key TTsk stored in the key storage means 31 according to the TT encryption method to generate an electronic coupon (special offer information).
Through the above operations, the privilege distribution system 100 can encrypt the privilege acquisition data, and distribute the signed encrypted data (c, σ) to which the signature has been added, in EMD in accordance with the distribution of the program.

This allows the user's privilege acquisition device 3 to automatically acquire the privilege acquisition data m by using the EMD included in the program, regardless of the viewing form of the program, such as broadcast waves or communication.
Furthermore, the privilege distribution system 100 can prevent the privilege acquisition data m from being forged by the signature σ of the signed encrypted data (c, σ) distributed by EMD.
Furthermore, the privilege distribution system 100 uses a TT cipher as an encryption method, so that a different decryption key is used for each user's privilege acquisition device 3. This makes it possible to detect which user's decryption key is being used if an unauthorized privilege acquisition device 3 is generated.

Although the configuration and operation of the privilege distribution system 100 according to the embodiment of the present invention have been described above, the present invention is not limited to this embodiment.
Here, the privilege acquisition data m (signed encrypted data (c, σ)) is distributed by EMD, so that the same privilege is given to users who have viewed the program.

However, when a program is distributed through communication, since it is possible to identify the user who is viewing the program, different privilege acquisition data m may be distributed in the EMD depending on the number of times the user has viewed the program.
In this case, the privilege distribution system 100 may perform the operation shown in FIG.

In step S15, the privilege acquisition device 3 transmits a user-specific identifier (user ID; for example, an IP address) to the privilege acquisition data issuing device 2 in advance. This user ID may be transmitted, for example, at the same time that the privilege acquisition device 3 requests a program from a content server (not shown).

In step S16, the bonus acquisition data issuing device 2 receives the user ID. For example, the bonus acquisition data issuing device 2 may receive the user ID included in a program request to the content server from the content server.

In step S20A, the data encryption means 22 of the bonus acquisition data issuing device 2 encrypts the bonus acquisition data m input from outside corresponding to the program using the TT encryption method with the encryption key TTpk stored in the key storage means 21 to generate encrypted data c.
At this time, the data encryption means 22 encrypts the privilege acquisition data m associated with each user ID to generate encrypted data c. For example, the user ID and the privilege acquisition data m are associated with each other by a totaling means (not shown) that totalizes the number of times a program has been viewed by the user ID and associates different privilege acquisition data m with each number of times the program has been viewed.

In step S21A, the signature generation means 23 calculates a hash value of the privilege acquisition data m for each user ID using a predetermined hash function, and encrypts the hash value with the signature key SIGsk stored in the key storage means 21 to generate a signature σ (electronic signature) for each user ID.
In step S22A, the EMD sending means 24 sends the signed encrypted data (c, σ) obtained by adding the signature σ generated for each user ID in step S21A to the encrypted data c generated for each user ID in step S20A to the bonus acquisition device 3 as event metadata (EMD) to be distributed when the program is broadcast (distributed).
The subsequent operations are the same as those in FIG. 7, and therefore will not be described.
Through the above operations, the privilege distribution system 100 can issue different electronic coupons depending on the programs viewed by the user.

REFERENCE SIGNS LIST 100 Benefit distribution system 1 Key generation device 10 Signature key pair generation means 11 Encryption key pair generation means 12 Key transmission means 2 Benefit acquisition data issue device 20 Key reception means 21 Key storage means 22 Data encryption means 23 Signature generation means 24 EMD transmission means (event metadata transmission means)
3 Benefit acquisition device 30 Key receiving means 31 Key storage means 32 EMD receiving means (event metadata receiving means)
33 Data decryption means 34 Signature verification means 35 Benefit acquisition data transmission means 36 Encrypted benefit information reception means 37 Benefit information decryption means 4 Benefit issue device 40 Key reception means 41 Key storage means 42 Benefit acquisition data reception means 43 Signature verification means 44 Benefit information encryption means 45 Encrypted benefit information transmission means

Claims (6)

A privilege issuing device that issues privilege information associated with viewing of a program, a privilege acquisition data issuing device that issues privilege acquisition data for acquiring the privilege information, and a privilege acquisition device that adds a digital signature to the privilege acquisition data, transmits the digital signature to the privilege issuing device, and acquires the privilege information, in a privilege distribution system including the privilege acquisition data issuing device,
a data encryption means for encrypting the privilege acquisition data with an encryption key corresponding to a decryption key of a fraud tracing encryption method used by the privilege acquisition device to generate encrypted data;
a signature generating means for generating an electronic signature for the privilege acquisition data using a signature key corresponding to a verification key of a public key cryptosystem used by the privilege acquisition device and the privilege issuing device to verify the electronic signature;
an event metadata transmission means for transmitting signed encrypted data obtained by adding the digital signature generated by the signature generation means to the encrypted data as event metadata at the time of distribution of the program ,
The data encryption means encrypts individual privilege acquisition data in association with an identifier unique to the user,
The bonus acquisition data issuing device, wherein the event metadata transmitting means transmits individual signed encrypted data to the bonus acquisition device corresponding to the identifier . A privilege acquisition device that acquires privilege information associated with viewing of a program,
an event metadata receiving means for receiving, as event metadata for the program , signed encrypted data obtained by encrypting the privilege acquisition data for acquiring the privilege information with an encryption key of a fraudster tracing encryption system and adding an electronic signature generated from the privilege acquisition data with a signature key of a public key encryption system to the encrypted data;
a data decryption means for decrypting the encrypted data into reward acquisition data by using a decryption key corresponding to the encryption key of the fraudster tracing encryption method;
a signature verification means for verifying whether or not the electronic signature is a correct electronic signature of the privilege acquisition data decrypted by the data decryption means, using a verification key corresponding to a signature key used by the privilege acquisition data issuing device when generating the electronic signature;
a privilege acquisition data transmission means for transmitting signed privilege acquisition data, which is the privilege acquisition data decrypted by the data decryption means and to which the digital signature verified as correct by the signature verification means has been added, to a privilege issuing device;
an encrypted bonus information receiving means for receiving, from the bonus issuing device, encrypted bonus information obtained by encrypting the bonus information with the encryption key;
a bonus information decryption means for decrypting the encrypted bonus information into the bonus information by using the decryption key;
A privilege acquisition device comprising: A privilege issuing device that issues privilege information associated with viewing of a program,
a privilege acquisition data receiving means for receiving signed privilege acquisition data from a privilege acquisition device, the signed privilege acquisition data being the privilege acquisition data for acquiring the privilege information and an electronic signature generated by a privilege acquisition data issuing device that issues the privilege acquisition data using a signature key of a public key cryptosystem;
a signature verification means for verifying whether or not the electronic signature is a correct electronic signature of the bonus acquisition data by using a verification key corresponding to a signature key used by the bonus acquisition data issuing device when generating the electronic signature;
a privilege information encryption means for encrypting the privilege information into encrypted privilege information using an encryption key corresponding to a decryption key of a fraud tracing encryption method used by the privilege acquisition device when the electronic signature is verified to be correct by the signature verification means;
an encrypted bonus information transmitting means for transmitting the encrypted bonus information to the bonus acquisition device;
A bonus issuing device comprising: A bonus acquisition data issuing program for causing a computer to function as the bonus acquisition data issuing device according to claim 1 . A bonus acquisition program for causing a computer to function as the bonus acquisition device according to claim 2 . A bonus issuing program for causing a computer to function as the bonus issuing device according to claim 3 .

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