JPH11289325A - Information distribution method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the intensity of a cryptograph, even by using a standard ciphering system and to ensure security by preventing the acquisition of decoding key information due to illegal conspiracy or the like between users. SOLUTION: A user side transmits user identification information IP and request information to a transmitter, the transmitter obtains key information (K) and gives it to the user side by using a unidirectional function to be used in the public key ciphering technique, on the basis of a cryptographic key Ki regarding the demand information and the user identification information IP, the user side decodes the cryptographic key Ki on the basis of the key information (K) and the user identification information IP, and information which is enciphered on the basis of the cryptographic key Ki and is distributed by the transmitter is restored to a form that can be used on the basis of the decoded cryptographic key Ki.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention improves the security against unauthorized reception of information, in which only a specific user can decrypt and use generally encrypted information transmitted via a network. And an apparatus for distributing information.

[0002]

2. Description of the Related Art An information distribution system in which encrypted information transmitted via a network is made available only to a specific user is widely used especially in the broadcasting field. FIG. 5 is a block diagram showing a pay broadcasting apparatus disclosed in, for example, JP-A-5-284499 as a conventional information distribution method and apparatus. In FIG. 5, reference numeral 101 denotes a transmission source apparatus, 102 denotes a communication satellite, and 104 denotes a communication satellite. Source information to be transmitted, 105 is an encryption unit, 106 is an encryption / decryption key management unit for each use information, 107 is a communication unit, 108 is a billing unit, 109 is a transmission unit, and 110 is source information 104 And a television broadcasting station having an encryption unit 105 and a transmission unit 109, and 111 is an encryption / decryption key management unit 1
06, a communication unit 107, and a billing unit 108.

Reference numeral 121 denotes decryption means for the encryption of the encryption means 105, 122 denotes reception means, 123 denotes communication means for transmitting / receiving reception permission and encryption information to / from the communication means 107 of the transmission source apparatus 101, and 124 denotes encrypted data. Recording means for recording the broadcast information, 125 is a display device for displaying the decrypted information, and 126 is a recording / playback control means having a decryption key. Reference numeral 127 denotes a user-side device including a decoding unit 121, a receiving unit 122, a communication unit 123, a recording unit 124, a display device 125, a recording and reproduction control unit 126, and the like.

Next, the operation will be described. On the receiving side,
If necessary information is determined in advance, the communication unit 123
A request is made to the management station 111 via the server, and a key for encryption / decryption of necessary information is known and taken into its own recording / playback control means 126. Thereafter, in the transmission source device 101 such as a television broadcasting station, a key corresponding to the program is extracted from the encryption / decryption key management unit 106, the transmission source information 104 is encrypted by the encryption unit 105, and the transmission unit 109 and the communication satellite 102 Is transmitted to the user-side device 127 via. Next, the user-side device 127 extracts the key information for decryption given from the transmitting side from the recording / reproduction control means 126, and decrypts and reproduces the information by the decryption means 121, so that the information of the transmission source can be correctly obtained. The data is decrypted and displayed on the display device 125.

[0005]

Since the conventional information distribution method and apparatus are configured as described above, when other users use the information sent from the transmission source,
If the encryption key information transmitted and received by the communication unit 123 of the user device 127 is intercepted, there is a problem that the information can be received and decrypted without obtaining permission. In addition, there is a risk that the decryption information will be circulated on the user side, and unauthorized eavesdropping by malicious eavesdroppers, etc.Therefore, there is a solution to encrypt each individual user, but broadcasting from satellites etc. However, there is a problem that it is not easy to realize the transmission for a large number of users.

[0006] The present invention has been made to solve the above problems, and once the registration of use between the user side and the transmission source has been made, only the user side can decrypt the code. In addition, the standard encryption method can be used for the information flowing over the network and the strength of the encryption can be ensured, and the security is secured by preventing the acquisition of decryption key information due to unauthorized collusion among users. It is an object of the present invention to obtain a method and apparatus for distributing information.

[0007]

According to an information distribution method according to the present invention, a user transmits user identification information for identifying the user and request information to a transmission source prior to use of the information.
Based on the user identification information transmitted from the user side and the encryption key Ki for the request information, key information (K) is calculated at the transmission source using a one-way function used in public key cryptography. Giving the calculated key information (K) to the user via a communication network, and based on the provided key information (K) and the user identification information, Decrypts the encryption key Ki, and decrypts the encryption key Ki;
The information encrypted by the source based on the information and distributed from the source via the communication network is restored to a form that can be used by the user based on the decrypted encryption key Ki. It was made.

[0008] In the information distribution method according to the present invention, the user side transmits a preset IP address of the user side to the transmission source as user identification information before using the information.

[0009] The information distribution method according to the present invention is such that the user side transmits, as user identification information, identification information determined for each user who can be externally input to the transmission source prior to use of the information. is there.

[0010] The information distribution method according to the present invention provides a communication path for transmitting user identification information and request information from a user to a transmission source, and communication of key information (K) given from the transmission source to the user. A communication network serving as a route is separated from a communication network for distributing information from the transmission source to the user side.

[0011] An information distribution apparatus according to the present invention comprises a communication network for connecting a source and a user, and a user for identifying the user who transmitted the source to the source prior to using the information. Receiving identification information and request information, and calculating key information (K) using a one-way function used in public key cryptography based on the encryption key Ki and the user identification information for the received request information; The calculated key information (K)
Registering means for giving to the user, the key information (K) given by the user registering means and the user identification information of the user, and the encryption key on the user side. An encryption key decrypting means for decrypting Ki; an encrypting means for encrypting information distributed at the source based on the encryption key Ki; and a communication network encrypted by the encryption means and transmitted from the source. Distribution information decrypting means for decrypting information distributed via the encryption key Ki decrypted by the encryption key decrypting means into a usable form.

[0012] An information distribution apparatus according to the present invention is configured such that a user transmits to a transmission source prior to use of information as identification information determined for each user who can input externally as user identification information. It is.

[0013] In the information distribution apparatus according to the present invention, the user side transmits user identification information and request information to the transmission source prior to use of the information, and key information (K) provided from the transmission source to the user side. The information is transmitted and received via the registration communication network, and the information is distributed from the transmission source to the user via the information distribution communication network.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration of the information distribution apparatus according to the first embodiment. In FIG. 1, 1 is a source device, 2 is a first user device, 3 is a second user device, 11 is transmission information before encryption in the source device 1, and 12 is the encrypted information. A first encryption unit (encryption unit) for encrypting the previous transmission information, and a transmission unit (user registration unit) 18. 19 is a receiving means (user registration means) in the user device, 21 is a first decrypting means (distribution information decrypting means), 22 is a second decrypting means (cryptographic key decrypting means), 23 Is the local station identification information (IP) of the first user-side device 2; 24 is key information (K) individually given to the user of the first user-side device 2;
Is decrypted display information. The configuration of the second user-side device 3 is the same as that of the first user-side device 2 except that the own-station identification information (IP) indicated by reference numeral 23 of the first user-side device 2 is used. The own station identification information (IP ′) indicated by the corresponding reference numeral 33 is different from the key information (irrelevant to the key information K) corresponding to the reference numeral 24 of the first user apparatus 2. In addition, 90 is a communication network.

FIG. 2 is a functional block diagram showing functions necessary for obtaining key information in the information distribution apparatus according to the first embodiment in a block form. 2, the same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 2, reference numeral 41 denotes a table (user registration means) of encryption keys (Ki) corresponding to information distributed by the first encryption means 12, that is, request information used to encrypt transmission information, The second encryption means (user registration means) 43 is a receiving means (user registration means), which is configured in the transmission source device 1. Reference numeral 51 denotes a transmission unit (user registration unit) of the first user-side device 2, and reference numeral 52 denotes request information transmitted from the first user-side device 2.

Next, the operation will be described. First, prior to using the information, the user makes an IP
The transmission unit transmits own station identification information (IP) such as an address and request information (requested information). In FIG. 2, the user of the user-side apparatus 2 has its own station identification information (IP) 23 and request information (requested information) 52 prior to using the information.
Is transmitted to the transmission source device 1 by the transmission means 51.
The source device 1 checks the encryption key (Ki) for the request information 52 requested by the user device 2 as the reception source from the encryption key table 41, and also identifies the user's own station identification information (I
Taking into account P), the key information (K) 24 for giving the encryption key by the second encryption means 42 using the one-way function used in the public key encryption technique is represented by K = f (Ki, IP). Is calculated by the following equation (1) and transmitted to the user device 2 via the transmission means 18 and the communication network 90.

The above equation (1) is, for example, K = (Ki +
IP) ** e mod n, that is, the sum of Ki and IP raised to the power e (an integer not exceeding n) in a calculation modulo n can be used as a one-way function. Here, n is a product of two large prime numbers p and q, and e is an RSA method that satisfies the relationship of equation (2) represented by e * d = (p−1) * (q−1) * t + 1. Public key. In the above equation (2), d is a key used for decryption, and t is an integer. Here, since the value of K greatly changes from Ki and IP, even if K and IP are known, it is impossible to know Ki without knowing d used for decoding.

The user obtains the key information (K) 24, and thereafter uses the key information (K) 24. Here, if the one-way function is used to calculate the key information (K), even if the user owns the key information (K) 24 and the own station identification information (IP), the two information can be used. It is difficult to restore Ki information. Therefore, even if the key information (K) 24 is illegally circulated to another user, it is practically impossible to obtain the key information (K ') that matches the self-identification information (IP') of the other user. It is.

Next, the distribution and use of ordinary information will be described with reference to FIG.
It is explained based on. Normally, the transmission source device 1 encrypts the information to be distributed, that is, the transmission information 11 to be transmitted, by the first encryption means 12 using the encryption key Ki determined for each information item, and broadcasts the information on the communication network 90 in a broadcast manner. ing. The user device obtains the key information (K) 24 for the information to be used as described above. This information is used together with the own station identification information (IP) 23 to obtain an encryption key Ki by the second encryption / decryption means 22 using an expression represented by Ki = f ^-1 (k, IP). Here, decoding in the case of using the RSA method is performed by an equation represented by (Ki + IP): K ** d mod n. Here, (Ki + IP) ** e ** d mod n = (Ki + I
P) The property on the number theory called mod n is used. Here, a person (and a computer) who does not know d requires a time of several thousand years or more even if it is calculated by the fastest computer, and is impossible in terms of calculation amount. Obtaining Ki from Ki + IP can be easily performed by subtracting i.

Next, using the decryption key Ki on the network obtained as described above, the first decryption means 21
To restore the network information to a usable form, display it as display information 25, and use it by the user of the user-side device 2. Here, the user of the user-side device 2 receives the key information (K).
Is passed to the user of another user device 3, even if the user of the user device 3 inputs the key information (K) as the key information 34, the own station identification information (IP ′) 33 Are different, the encryption key (Ki) for decryption cannot be obtained. Further, the key information (K) 24 and the own station identification information (IP) 2
From 3, it is practically impossible to estimate key information that can be used by other users.

Further, in realizing this user-side device, the second encryption / decryption means 22 and the first decryption means are realized on the same integrated circuit, so that the information extraction by the user is substantially achieved. What is impossible can be easily realized by using a current programmable integrated circuit.

As is clear from the above description, since the encryption method on the communication network completely hides the key Ki, a conventional secret key encryption technique such as the DES method can be used, so that the encryption strength is maintained. And simplification of encryption and decryption can be easily realized. Further, the source device can transmit the encrypted information without being aware of the user except when giving permission, so that there is a great advantage in constructing a broadcast system.

As described above, according to the first embodiment, the user of the user-side device sends his / her own identification information (IP) and request information (requested information) to the transmission source device 1 before using the information. Is transmitted, and the transmission source device 1 transmits the encryption key (K) to the request information requested by the user side device as the reception source.
i) and key information (K) is calculated from the user's own station identification information (IP) using a one-way function used in public key cryptography, and given to the user side device via the communication network 90. Thereafter, the user of the user-side device uses the given key information (K), and uses the key information (K) and the own-station identification information (IP) to generate an encryption key Ki.
When distributing information from the transmission source device 1 to the user device, the information to be distributed is encrypted based on the encryption key Ki, and the information is distributed to the user device. In the user side device, the obtained decryption key Ki is obtained.
And decrypts the distributed information into a form that can be used. For this reason, once the registration of the use is made between the user of the user device and the transmission source device, and the key information (K) is given to the user of the user device, the encryption is decrypted only by the user. In addition, a standard encryption method can be used for the information flowing over the communication network, and since the key information (K) is generated using a one-way function, other users can use the key information (K). It is difficult to know the key information corresponding to the user identification information from (K). Even if a standard encryption method is used for the information flowing on the network, the encryption strength can be secured. There is an effect that an information distribution method and an information distribution apparatus that can prevent the acquisition of decryption key information due to illegal collusion between the users and secure security can be obtained.

Embodiment 2 FIG. In the first embodiment, the self-station identification information of the user-side device is used as information inside the device like an IP address. However, as shown in FIG. 3, the self-station identification information can be input from outside. May be adopted. In the case of such a configuration, there is an effect that an information distributing apparatus that can use information at a place where a user has moved can be realized. In addition, when used in an educational system, grade information and the like are often managed by individual identification codes such as employee numbers, so input of own station identification information in such use is a burden on the user. There is an effect that the effectiveness when realized can be expected without increasing.

Embodiment 3 In each of the embodiments described above, user registration and information distribution are performed on the same communication network. However, as shown in FIG. 4, the registration communication network (registration communication network) 9 is used.
By dividing the communication network into a communication network 1a and a communication network for information distribution (communication network for information distribution) 91b, there is an advantage that a large amount of information transmission lines such as satellite broadcasting can be used when distributing a large amount of information such as broadcasting. In FIG. 4, reference numeral 61 denotes a transmission source device 1 for transmitting encrypted transmission information 11 to a communication network 91b for information distribution.
Is a receiving means for receiving the transmission information 11 from the communication network 91b by the user side device 2. Note that, when realized by a television or the like, a numerical key for setting a channel number of a remote controller can be used as a key information input unit.

[0026]

As described above, according to the present invention, the user side transmits user identification information for identifying the user side and request information to the transmission source prior to use of the information, and the transmission source User identification information and encryption key K for the request information
Based on i, the key information (K) is calculated using a one-way function used in the public key cryptography, and the key information (K) is provided to the user via a communication network. When the information distributed via the communication network is used on the user side, the user uses the key information (K) and the encryption key Ki based on the user identification information on the user side. Decrypts the information encrypted based on the encryption key Ki and distributed from the source via the communication network, to the decrypted encryption key Ki on the user side.
Is configured so that it can be used on the basis of, if the registration of use is made between the user and the sender, the encryption can be decrypted only by the user, and especially the key information (K) Since the one-way function is used for the calculation, it is impossible to decrypt the encryption key Ki on the user side only with the key information (K) and the user identification information on the user side. And the key information (K) for other users.
Since it is difficult to know the key information corresponding to the user identification information of the user, the encryption strength can be secured even if a standard encryption method is used for the information flowing over the network, Thus, there is an effect that security can be ensured by preventing the acquisition of decryption key information due to illegal collusion or the like.

According to the present invention, the user identification information to be transmitted to the transmission source by the user prior to use of the information is configured to the preset IP address of the user. If the registration of use is made between the devices, the decryption can be performed only by the user using the IP address of the user, and in particular, a one-way function is used to calculate the key information (K). Therefore, on the user side, the encryption key Ki
In order to decrypt the key information (K) and the IP address of the user, it is not possible to decrypt the key information (K). Because it is difficult to know the information, even if a standard encryption method is used for the information flowing on the network, the strength of the encryption can be ensured. This has the effect of preventing safety and ensuring safety.

According to the present invention, the user identification information to be transmitted to the transmission source by the user prior to the use of the information is configured as identification information determined for each user who can be input externally. Using the identification information input by the user, the user can decrypt the code only on the user side, and can also flexibly select the identification information, such as an identification number for each individual such as an employee number, for example. Since the one-way function is used to calculate the information (K), it is impossible for the user to decrypt the encryption key Ki only with the key information (K) and the identification number. Also, it is more difficult for other users to know the key information corresponding to the user's own identification information from the key information (K).
Even if a standard encryption method is used for the information flowing over the network, the strength of the encryption can be ensured, and the effect of preventing the acquisition of decryption key information due to unauthorized collusion between users and ensuring the security can be secured. is there.

According to the present invention, a communication path for transmitting user identification information and request information from a user to a transmission source and a communication path for key information (K) provided from the transmission source to the user side Since the network is configured to be separated from a communication network serving as a communication path for distributing information from the source to the user side, a network for distributing information from the source to the user side is provided. A communication network with a large amount of information can be used as the communication network. Even if a standard encryption method is used for the information flowing on the network, the strength of the encryption can be ensured. This has the effect of preventing the acquisition of decryption key information and ensuring security.

According to the present invention, a communication network for connecting a source and a user, and user identification information for identifying the user who transmitted the source to the source prior to use of the information are provided. Upon receiving the request information, based on the encryption key Ki and the user identification information for the received request information,
User registration means for calculating key information (K) using a one-way function used in public key cryptography, and providing the calculated key information (K) to the user side; Key decryption means for decrypting the encryption key Ki on the user side based on the key information (K) and the user identification information on the user side; Encryption means for encrypting based on the key Ki; and the encryption key Ki obtained by decrypting the information encrypted by the encryption means and distributed from the source via the communication network by the encryption key decryption means. And a distribution information decrypting means for decrypting the information into a usable form based on the information, so that if the use is registered between the user and the sender, the encryption can be decrypted only by the user. Yes, especially one way to calculate key information (K) Since the user uses the key information (K) and the user identification information on the user side, it is impossible to decrypt the encryption key Ki on the user side because the number is used. Key information (K)
Since it is difficult to know the key information corresponding to the user identification information of the user, the encryption strength can be secured even if a standard encryption method is used for the information flowing over the network, Thus, there is an effect that security can be ensured by preventing the acquisition of decryption key information due to illegal collusion or the like.

According to the present invention, the user identification information transmitted from the user to the transmission source prior to the use of the information is configured to be identification information determined for each user who can input externally. Using the identification information input by the user according to the situation, the user can decrypt the code only on the user side, and furthermore, the identification information can be flexibly selected such as an individual identification number such as an employee number, In addition, since a one-way function is used to calculate the key information (K), it is impossible for the user to decrypt the encryption key Ki only with the key information (K) and the identification number. Since it is more difficult for other users to know the key information corresponding to the user's own identification information from the key information (K), a standard encryption method is used for the information flowing on the network. Even cryptographic It is possible to secure a degree, safety to prevent the acquisition of decryption key information by unauthorized collusion like among users there is an effect that can be secured.

According to the present invention, the communication network connecting the transmission source and the user side is provided with a communication path of the user identification information and the request information transmitted from the user side to the transmission source prior to the use of the information. And a registration communication network serving as a communication path for key information (K) given from the source to the user, and an information distribution serving as a communication path for distributing information from the source to the user. And a communication network for distributing information from the transmission source to the user side, a communication network having a large information transmission amount can be used. Even if a standard encryption method is used for the information flowing to the user, the strength of the encryption can be ensured, preventing the acquisition of decryption key information due to unauthorized collusion between users and ensuring security. There is an effect that can be secured.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an information distribution device according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram showing functions necessary for obtaining key information in the information distribution apparatus according to the first embodiment of the present invention in a block form.

FIG. 3 is a block diagram showing a configuration of a user-side device in an information distribution device according to a second embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of an information distribution device according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a pay broadcasting apparatus disclosed in Japanese Patent Application Laid-Open No. 5-284499 as a conventional information distribution method and apparatus.

[Explanation of symbols]

12 First encryption means (encryption means), 18, 51
Transmitting means (user registration means), 19, 43 receiving means (user registration means), 21 first decryption means (distribution information decryption means), 22 second encryption / decryption means (encryption key decryption means) ), 41 Encryption key (K
Table i) (user registration means), 42 second encryption means (user registration means), 90 communication network, 91a
Communication network (communication network for registration), 91
b Communication network (information distribution communication network).

Claims (7)

[Claims] 1. A first step in which a user transmits user identification information for identifying the user side and request information to a transmission source prior to use of the information, and the use transmitted in the first step. User identification information,
A second step of calculating key information (K) at the source using a one-way function used in public key cryptography based on an encryption key Ki for the request information; and a key calculated in the second step. A third step of providing information (K) to the user via a communication network; and the key information (K) provided in the third step and user identification information of the user. A fourth step of decrypting the encryption key Ki on the user side; a fifth step of encrypting information distributed at the source based on the encryption key Ki; Restoring the information encrypted in the step and distributed from the transmission source via the communication network to a form usable by the user based on the encryption key Ki decrypted in the fourth step; Information distribution method with steps Law. 2. The method according to claim 1, wherein the user identification information transmitted to the transmission source by the user prior to the use of the information in the first step is a preset IP address of the user. 1. The information distribution method described in 1. 3. The method according to claim 1, wherein the user identification information transmitted to the transmission source by the user prior to the use of the information in the first step is identification information determined for each user who can input externally. The information distribution method according to claim 1. 4. A communication path for transmitting user identification information and request information from a user to a transmission source in a first step, and key information (K provided from the transmission source to the user in a third step) 4. The communication network according to claim 1, wherein the communication network serving as a communication path is separated from a communication network serving as a communication path for distributing information from a source to the user side. The information distribution method according to any one of the above. 5. A communication network for connecting a transmission source and a user, and receiving user identification information and request information for identifying the user who transmitted the transmission to the transmission source prior to use of the information. And
Key information (K) is calculated using a one-way function used in public key cryptography based on the encryption key Ki and the user identification information for the received request information, and the calculated key information (K) is calculated. User registration means to be given to the user side; and the encryption key Ki on the user side based on key information (K) given by the user registration means and user identification information of the user side. Encryption key decryption means for decrypting the information, encryption means for encrypting information distributed from the source based on the encryption key Ki at the source, and encryption information encrypted by the encryption means from the source. An information distributing apparatus comprising: a distribution information decrypting unit that decrypts information distributed via a communication network into a usable form based on the encryption key Ki decrypted by the encryption key decrypting unit. 6. The apparatus according to claim 5, wherein the user identification information transmitted by the user to the transmission source prior to use of the information is identification information determined for each user who can input externally. Information distribution device. 7. A communication network for connecting between a transmission source and a user, comprising: a communication path of user identification information and request information transmitted by the user to the transmission source prior to use of the information; A registration communication network serving as a communication path for key information (K) originally given to the user side, and an information distribution communication network serving as a communication path for distributing information from the source to the user side. The information distribution apparatus according to claim 5, wherein the information distribution apparatus is separated from the information distribution apparatus.