JP2004213679A - Remote education system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a remote education system in which there is little possibility that an encryption key is obtained by a third person and the encryption key which does not have to be managed by a user is exchanged and which is excellent in secrecy in a remote education system utilizing a communication satellite. <P>SOLUTION: In this remote education system in which interactive information transmission is performed by the communication satellite and a ground network between a transmission center having an information transmission function to the communication satellite and an information reception function from the ground network and a plurality of participant classrooms having an information transmission function to the ground network and an information reception function from the communication satellite, a cryptographic key is transmitted from the transmission center to the participant classrooms, first information processors that the participant classrooms have use the cryptographic key to encipher digital data to be enciphered digital data, the enciphered digital data are transmitted from the participant classrooms to the transmission center and a second information processor that the transmission center has decodes the enciphered digital data with a decoding key corresponding to the cryptographic key. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a distance education system using a communication satellite and a terrestrial network.

  With the rapid development of the Internet in recent years, interactive video conference systems and distance learning systems using the Internet have been proposed. However, even if the band used for data communication is widened, it is not possible to exclude the possibility that a transmission time difference occurs for each user due to the nature of the information transmission method of the Internet.

  Therefore, a system has been proposed in which a communication satellite is used as a means for simultaneously transmitting video and audio to all users, and information transmission via the Internet is used in order to obtain bidirectionality. A conventional distance learning system will be described with reference to the drawings. FIG. 8 is a diagram showing an outline of a distance learning system using a communication satellite and the Internet network. The distance learning system includes a transmission center 1, a communication satellite 2, a classroom 3 and the Internet 4. The transmission center 1 has a transmission antenna 5, an information processing device 6, and a lecturer-side camera 7, and the student classroom 3 has a reception antenna 8, an information processing device 9, and a student-side camera 10. There are a plurality of student classrooms having the same configuration as the student classroom 3.

  The lecturer who is the facilitator of the lecture gives a lecture toward the lecturer-side camera 7 in the transmission center 1, and the information processing device 6 connected to the lecturer-side camera 7 provides lecture video information (including audio) taken by the lecturer-side camera 7. Is transmitted from the transmitting antenna 5 to the communication satellite 2. At this time, the lecture video information is digitized by encoding and encrypting the lecture video information as needed, and modulated using quadrature phase shift keying (QPSK) together with digital data used by a computer. By doing so, digital information is transmitted by radio waves.

  The communication satellite 2 propagates the radio wave received from the transmission antenna 5 to the ground, the reception antenna 8 provided in each student classroom 3 receives the radio wave, and the information processing device 9 demodulates the phase modulation to give lecture video information. And digital data. The extracted video information is displayed on a television screen, and the digital data is stored in the information processing device 9. When transmitting information at the transmission center 1, the information processing device 6 scrambles the video information and the digital data, and the information processing device 9 in the student classroom 3 cancels the scramble, so that only the contractor can perform the scrambling. Lecture video information and digital data can be received.

  In the participant classroom 3, the participant speaks in front of the participant camera 10 and captures the participant image information (including audio) while viewing the instructor image information displayed on the television screen. The student camera 10 and the information processing device 9 connected to the Internet 4 digitize the student image information and add digital data, and transmit the student image information and digital data via the Internet 4 to the information of the transmission center 1. It is transmitted to the processing device 6.

  The information processing device 6 of the transmission center 1 combines the video and audio captured by the instructor-side camera 7 and the student video information transmitted via the Internet 4 into lecture video information that can be displayed on one screen. , From the transmitting antenna 5 to the student classroom 3 via the communication satellite 2. As a result, each student can view the lecture image information including the student image information, and a conversation between the students can be established.

  As described above, in the video conference system and the distance learning system that have been conventionally proposed, the student image information from each student classroom 3 is transmitted to the transmission center 1 via the Internet 4, and each student classroom 3 receives the lecture image. By receiving the information as radio waves from the communication satellite 2, a two-way remote education system with simultaneousness for students at a plurality of locations has been established.

However, in the above-described conventional video conference system and remote education system, the video information and digital data from the transmission center 1 are scrambled and transmitted. However, the video information and the digital data from the student classroom 3 are not encrypted, and there is a possibility that the video information and the digital data may be illegally intercepted by others due to the characteristics of information communication via the Internet.
It is necessary to increase the confidentiality of video information and digital data from the student classroom to the transmission center by using some encryption technology. However, in the case of using a common key encryption technique, it is necessary to prevent a third party from obtaining the key. Further, in the case of using the encryption technology of the public key system, there is a problem that since the possibility that the secret key can be calculated from the public key cannot be said to be zero, the psychological anxiety of the user remains.

Therefore, it is necessary to take measures to make it impossible for a third party to obtain an encryption key used for encryption. However, the transfer of the encryption key via the Internet may be intercepted by a third party. Further, in a case where the encryption key is recorded on a magnetic recording medium or the like and the recording medium is mailed, the user himself / herself must strictly manage the encryption key. Furthermore, if the encryption key is obtained by a third party, it is necessary to update the encryption key, and labor and time are spent on updating and managing the encryption key.

The present invention has been made in view of the above conventional problems. In a remote education system using a communication satellite, the possibility that an encryption key is obtained by a third party is low, and the user manages the key. It is an object of the present invention to provide a highly confidential distance education system capable of exchanging unnecessary encryption keys.

  A remote education system according to the present invention for solving the above-mentioned problems includes a transmission center having a function of transmitting information to a communication satellite and a function of receiving information from a terrestrial network, a function of transmitting information to a terrestrial network, and receiving information from a communication satellite. In a distance learning system for performing bidirectional information transmission between a plurality of student classrooms having functions by a communication satellite and a ground network, an encryption key is transmitted from the transmission center to the student classroom, A first information processing device having the encryption key encrypts the digital data using the encryption key to generate encrypted digital data, and transmits the encrypted digital data from the student classroom to the transmission center; A second information processing device of the center decrypts the encrypted digital data using a decryption key corresponding to the encryption key.

  When transmitting the encryption key from the transmission center to the student classroom via the communication satellite, the information communication to the student classroom via the communication satellite is scrambled and transmitted. The information communication from the student classroom to the transmission center is encrypted digital data, thereby increasing the confidentiality of the communication.

  Further, a distance education system according to the present invention for solving the above-mentioned problems has a transmission center having an information transmission function to a communication satellite and an information reception function from a terrestrial network, In a remote education system for performing bidirectional information transmission between a plurality of student classrooms having an information receiving function by a communication satellite and a terrestrial network, an encryption key and an encryption program are transmitted from the transmission center to the student classroom. The first information processing device of the student classroom encrypts digital data using the encryption key according to the encryption program to generate encrypted digital data, and sends the encrypted digital data from the student classroom to the transmission center. The encrypted digital data is transmitted, and a second information processing device of the transmission center is adapted to execute a decryption program corresponding to the encrypted program. Wherein the decoding by the decoding key to the encrypted digital data corresponding to the encryption key in accordance grams.

  When transmitting the encryption key and the encryption program from the transmission center to the student class via the communication satellite, the information communication to the student class via the communication satellite is scrambled and transmitted. In addition, the encrypted program can be securely and securely transmitted to the student classroom, and the information communication from the student classroom to the transmission center is encrypted digital data, thereby increasing the confidentiality of the communication.

  Further, in the distance education system according to the present invention for solving the above-mentioned problems, the encryption key and the decryption key are key pairs created by key generation means of the second information processing device.

  Since the key generation means of the information processing device provided in the transmission center creates a key pair of an encryption key and a decryption key, it is possible to manage the encryption key and the decryption key on the transmission center side, and in the student classroom side There is no need to manage the encryption key, and it is possible to reduce the labor and the possibility of information leakage associated with the management of the encryption key.

  Further, a distance education system according to the present invention for solving the above-mentioned problem is characterized in that the encryption key and / or the encryption program are updated regularly or irregularly.

  By updating the encryption key and the encryption program, it is possible to reduce the possibility that the encryption key and the encryption algorithm currently used are known to a third party, so that the confidentiality of the communication is improved.

  Further, a distance education system according to the present invention for solving the above-mentioned problem is characterized in that the encryption key and / or the encryption program are transmitted in an encrypted targeted distribution.

  In addition to transmitting encryption keys and encryption programs via communication satellites, by using targeted distribution, third parties cannot receive encryption keys and encryption programs, so communication confidentiality is reduced. Increase.

  Further, in the distance education system of the present invention for solving the above-mentioned problems, the terrestrial network may be any one of a telephone line network, an ISDN network, a cable television network, an optical fiber network, a communication by a mobile phone, a wireless communication, and a satellite communication. Or a combination thereof.

  Since highly confidential information communication can be performed irrespective of the form of the terrestrial network, a wider range of choices can be made when constructing a system, and it is possible to reduce costs related to system construction and improve communication quality.

  Further, a distance education system according to the present invention for solving the above-mentioned problem is characterized in that the encryption program is selected according to the type of the ground network.

  By selecting an encryption program according to the communication environment used by the student classroom, it is possible to increase confidentiality even if it takes a long time to encrypt and decrypt data in a communication environment where information is easily leaked. Alternatively, in a communication environment in which information is difficult to leak, it is possible to select to complete processing in a short time even if confidentiality is relatively low, and it is possible to construct a flexible system.

  According to another aspect of the present invention, there is provided a computer, comprising: a procedure for generating an encryption key and a decryption key; and transmitting the encryption key to a student classroom via a communication satellite by means of encrypted targeted distribution. And a program for executing the procedure.

  When the information processing device of the transmission center executes the program, the encryption key can be transmitted to the student classroom without being intercepted by a third party.

  According to another aspect of the present invention, there is provided a computer, comprising: receiving an encrypted target limited distribution from a communication satellite and receiving an encryption key; and encrypting digital data using the encryption key. And transmitting the encrypted digital data to a transmission center via a terrestrial network.

  By executing this program by the information processing device in the student classroom, the encryption key transmitted from the transmission center is received without being intercepted by a third party, and digital data is encrypted with the received encryption key. It is possible to transmit the encrypted digital data to the transmission center, and it is possible to perform highly confidential information communication even in information communication via the Internet.

  In addition, the present invention for solving the above-mentioned problems provides a computer with a step of receiving encrypted digital data from a terrestrial network, and a step of using the decryption key to decrypt the encrypted digital data into digital data. Is a program for executing.

When the information processing device of the transmission center executes this program, the student classroom can decrypt the encrypted digital data and convert the encrypted digital data into digital data. Also, highly confidential information communication can be performed.

  To transmit the encryption key and the encryption program to the student classroom from the transmission center via the communication satellite, to securely and reliably transmit the encryption key and the encryption program for encrypting the digital data to the student classroom. The communication of information from the student classroom to the transmission center is converted into encrypted digital data, thereby increasing the confidentiality of the communication. Also, since the key generation means of the information processing device provided at the transmission center creates a key pair of an encryption key and a decryption key, it is possible to manage the encryption key and the decryption key on the transmission center side. There is no need to manage the encryption key on the side, and it is possible to reduce the labor involved in the management of the encryption key and the possibility of information leakage.

Updating the encryption key and encryption program can reduce the risk that a third party will be able to know the encryption key and encryption algorithm currently in use. By using targeted distribution in addition to transmitting the key and the encryption program, it becomes impossible for a third party to receive the encryption key and the encryption program, so that the confidentiality of the communication is improved. Furthermore, since highly confidential information communication can be performed regardless of the form of the terrestrial network, a wider range of choices can be made when constructing a system, and it is possible to reduce the cost of system construction and improve communication quality. Become.

(Embodiment 1)
Hereinafter, Embodiment 1 which is an example of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a remote education system according to the first embodiment, which comprises a transmission center 1, a communication satellite 2, a classroom 3, and the Internet 4 as a ground network. The terrestrial network means an information communication network capable of performing information communication between the transmission center 1 and the attending classroom 3, and is a telephone line network, an ISDN network, a cable television network, or an optical fiber network, and is physically connected. Communication using a mobile phone, wireless communication, or satellite communication that is not performed may be used. Although the Internet 4 is a network using TCP / IP (Transmission Control Protocol / Internet Protocol), it is merely an embodiment of the present invention and may be a network using another protocol. . The transmission center 1 has a transmission antenna 5, an information processing device 6, and a lecturer-side camera 7, and the student classroom 3 has a reception antenna 8, an information processing device 9, and a student-side camera 10. There are a plurality of student classrooms having the same configuration as the student classroom 3.

Further, as shown in FIG. 2, the information processing device 6 of the transmission center 1 has a CPU unit 21, a student information database 22, a key generation unit 23, an information storage unit 24, and an input unit 25.
The CPU unit 21 performs all arithmetic processing and control of video information and digital data in the information processing device 6, and includes a memory, a video processing unit, a communication unit, and the like (not shown).
The student information database 22 records and manages student attribute information such as the name and address of each student classroom, the number of viewers, the number of remarks, test results, and belonging groups.
The key generation means 23 creates a key pair of the encryption key 41 and the decryption key 42. The relationship between the encryption key 41 and the decryption key 42 is that if data encrypted by the predetermined algorithm using the encryption key 41 can be decrypted only by the predetermined algorithm using the decryption key 42, Although good, it is desirable that it is difficult to derive the decryption key 42 from the encryption key 41 even when the encryption key 41 is obtained by another person.
The information storage means 24 is a device for recording data such as student video information, lecture video information, and digital data, and is a recording medium such as a magnetic disk, a magneto-optical disk, or a CD-ROM. Is stored in a viewable format such as MPEG1 or MPEG2.
The input unit 25 is a device such as a keyboard, a mouse, a touch panel, and a voice recognition device, and the instructor inputs a command to the information processing device 6.

As shown in FIG. 3, the information processing means 9 of the student classroom 3 has a CPU section 31, a video information connection means 32, and an information storage means 33.
The CPU section 31 performs arithmetic processing and control of video information and digital data in the information processing device 9, and has a memory, a video processing unit, a communication unit, and the like (not shown).
The video information connection means 32 is a means for transmitting the student video information to the transmission center 1 via the Internet 4, and transmits the student video information only when receiving a call instruction from the transmission center 1. .
The information storage means 33 is a device for recording data such as student image information, lecture image information, and digital data, and is a recording medium such as a magnetic disk, a magneto-optical disk, or a CD-ROM. Is stored in a viewable format such as MPEG1 or MPEG2.

  Next, the operation of the distance learning system according to the first embodiment will be described with reference to the drawings. FIG. 4 is a flowchart showing an operation of encrypting information communication from the student classroom 3 to the transmission center 1 via the Internet 4 in the distance education system according to the first embodiment. The information transmission operation of the communication satellite 2 and the Internet 4 is omitted because there is no difference from the operation in the conventional example. Therefore, only the operation of the transmission center 1 and the student classroom 3 is described. However, transmission of lecture video information and digital data from the transmission center 1 to the student classroom 3 is performed via the communication satellite 2 and Transmission of student video information and the like to the transmission center 1 is realized by the respective protocols via the Internet 4.

<Step 1> At the transmission center 1, the information processing means 6 extracts the target student classroom 3a from the student information database 22 and activates the key generation means 23.
<Step 2> The key generation means 23 creates a pair of the encryption key 41 and the decryption key 42, and stores the decryption key 42 as one of the attribute information of the student classroom 3a in the student information database 22.
<Step 3> An access key including a password and a connection destination port number for establishing a connection between the transmission center 1 and the student lecture 3 so that the student image information can be transmitted to the transmission center 1 is transmitted to the CPU unit. 21 is created.
<Step 4> The encryption key 41 and the access key are distributed to the student classroom selected in step 2 together with the lecture video information in a targeted manner (the targeted limited delivery will be described later).
<Step 5> The student classroom 3a receives the encryption key 41 and the access key by targeted distribution.
<Step 6> The video information connection unit 32 makes a connection request with the transmission center 1 using the simultaneously received access key.
<Step 7> The CPU unit 21 of the transmission center 1 receives the connection request from the student classroom 3a. If the access key of the connection request is the same as the access key created in step 3, the CPU 21 The port is opened to establish a connection with the student classroom 3a.
<Step 8> In the student classroom 3a, the image of the student is captured by the camera 10 on the student side, and the information processing device 9 encodes the image of the student to obtain the student image information, and further uses the encryption key 41. And transmits it to the transmission center 1 as encrypted student image information.
<Step 9> The information processing means 6 decrypts the encrypted student video information by using the decryption key 42 belonging to the student classroom 3a recorded in the student information database 22, and And
<Step 10> The transmission center 1 creates lecture video information by synthesizing the student video information from each student classroom 3a selected in step 2 and the video of the lecture taken by the instructor camera 7. , From the transmitting antenna 5 via the communication satellite 2 to all the classrooms.
<Step 11> After the lecture is completed, when the instructor inputs a disconnection instruction from the input unit 25 of the information processing device 6, the information processing unit 6 updates the number of utterances of the student attribute information in the student information database 22. Then, an instruction to disconnect the connection is transmitted to the CPU unit 21.
<Step 12> The CPU 21 transmits the connection end instruction data to all the student classrooms, and thereafter closes the port that has received the student image information.
<Step 13> When the connection termination instruction data is received in the student classroom 3, the CPU 31 issues a connection termination instruction to the video information connection means 32 to stop the transmission of the student video information.

  As described above, a method in which the key generation means 23 creates a key pair of the encryption key 41 and the decryption key 42 for each communication may be used. Steps 1 to 10 are repeated regularly or irregularly in one communication. Thus, a method of updating the key pair may be used.

  Next, the limited distribution performed in step 4 of FIG. 4 will be described. The distribution of lecture video information and digital data by radio waves via the communication satellite 2 has a feature that information can be distributed to a large number of distribution destinations without delay. This means that the same information is distributed to the antenna 8 at the same time. In order to distribute specific information only to a specific student classroom, it is necessary to scramble the information. In the case of the distance learning system of the present invention, it is necessary for all the student classrooms to receive and view the lecture video information, and it is necessary to limit the receiving target of the call instruction data and the like separately.

  For the information received in all student classrooms, use a transmission method that only members can view by using the conventional descrambling by the decoder device, but separate encryption is required for information transmission that is limited to the target. The transmitted information is transmitted so that only the target student classroom can acquire the information.

  Next, the encryption procedure for targeted distribution will be described with an example. The method of encryption for targeted distribution is not limited, and it is used in a situation where real-time encryption and decryption of video information is required. Need not be illustrated here if possible.

A key code unique to each student classroom 3 is determined in advance as a base key, and is stored in the student information database 22 as one piece of student attribute information. The transmitted data is divided into packets and transmitted sequentially, but the first packet is encrypted using the base key and is transmitted to all student classrooms via communication satellites. Is decrypted using the base key, so that only the student classroom to be received can acquire packets.
The transmission center extracts one byte from the packet transmitted immediately before, performs encryption processing with the key code, and updates the key code. Similarly, the student classroom side extracts one byte from the packet obtained immediately before, performs the same encryption processing as the transmission center side with the key code, and updates the key code.
Thereafter, the packets are encrypted and decrypted using the sequentially updated key codes, and the key codes are also updated sequentially, so that all packets are encrypted and transmitted, and all packets are transmitted only in the classroom to be transmitted. Will be received.

  The base key for encrypting and decrypting the first packet is the same on the transmission center side and on the student classroom side, and in the subsequent key code update, the same one-byte extraction algorithm is extracted from the immediately preceding packet, and the key code is updated. Since the transmission center and the student classroom use the same encryption method to update the key, the updated key code will be the same for the transmission center and the student classroom each time. Even if the encrypted information is received in the classroom, only the target set in the transmission center can be decrypted, and as a result, the limited distribution can be performed.

By using the method of the first embodiment of the present invention described above, radio waves from communication satellites are received and descrambled by a decoder device, and information is transmitted by information communication using targeted distribution. The confidentiality is enhanced in three stages: only the student classroom can obtain the encryption key, and the information is encrypted using the encryption key. Therefore, if a third party attempts to eavesdrop on the contents by intercepting the information communication from the student classroom to the transmission center via the Internet, the third party must obtain the secret key from the public key of the public key encryption technology. Even if it can be decrypted, it is difficult to obtain the encryption key, so the confidentiality is greatly improved.
Further, since the encryption key can be transmitted from the transmission center side to the student classroom side, the key generation means generates the encryption key and the decryption key periodically or irregularly, and generates the encryption key. By transmitting the key pair to the student classroom and updating the key pair, confidentiality can be further enhanced.

(Embodiment 2)
Next, Embodiment 2 which is an example of the present invention will be described with reference to the drawings. The configuration of the remote education system according to the second embodiment is shown in FIG. 5 similarly to the first embodiment, and includes a transmission center 1, a communication satellite 2, a classroom 3, and the Internet 4 as a ground network. The terrestrial network means an information communication network capable of performing information communication between the transmission center 1 and the attending classroom 3, and is a telephone line network, an ISDN network, a cable television network, or an optical fiber network, and is physically connected. Communication using a mobile phone, wireless communication, or satellite communication that is not performed may be used. Although the Internet 4 is a network using TCP / IP (Transmission Control Protocol / Internet Protocol), it is merely an embodiment of the present invention and may be a network using another protocol. . The transmission center 1 has a transmission antenna 5, an information processing device 6, and a lecturer-side camera 7, and the student classroom 3 has a reception antenna 8, an information processing device 9, and a student-side camera 10. There are a plurality of student classrooms having the same configuration as the student classroom 3.

Further, the information processing device 6 of the transmission center 1 is shown in FIG. 6, and has a CPU unit 21, a student information database 22, a key generation unit 23, an information storage unit 24, an input unit 25, and an algorithm database 26.
The CPU unit 21 performs all arithmetic processing and control of video information and digital data in the information processing device 6, and includes a memory, a video processing unit, a communication unit, and the like (not shown).
The student information database 22 records and manages student attribute information such as the name and address of each student classroom, the number of viewers, the number of remarks, test results, and belonging groups.
The key generation means 23 creates a key pair of the encryption key 41 and the decryption key 42. The relationship between the encryption key 41 and the decryption key 42 is that if data encrypted by the predetermined algorithm using the encryption key 41 can be decrypted only by the predetermined algorithm using the decryption key 42, Although good, it is desirable that it is difficult to derive the decryption key 42 from the encryption key 41 even when the encryption key 41 is obtained by another person.
The information storage means 24 is a device for recording data such as student video information, lecture video information, and digital data, and is a recording medium such as a magnetic disk, a magneto-optical disk, or a CD-ROM. Is stored in a viewable format such as MPEG1 or MPEG2.
The input unit 25 is a device such as a keyboard, a mouse, a touch panel, and a voice recognition device, and the instructor inputs a command to the information processing device 6.
The algorithm database 26 is a database in which a plurality of encryption and decryption algorithms are recorded, and is used to execute encryption and decryption using the encryption key 41 and the decryption key 42 created by the key generation unit 23. A plurality of encryption programs 43 and decryption programs 44 are recorded.

As shown in FIG. 3, the information processing means 9 of the student classroom 3 has a CPU section 31, a video information connection means 32, and an information storage means 33.
The CPU section 31 performs arithmetic processing and control of video information and digital data in the information processing device 9, and has a memory, a video processing unit, a communication unit, and the like (not shown).
The video information connection means 32 is a means for transmitting the student video information to the transmission center 1 via the Internet 4, and transmits the student video information only when receiving a call instruction from the transmission center 1. .
The information storage means 33 is a device for recording data such as student image information, lecture image information, and digital data, and is a recording medium such as a magnetic disk, a magneto-optical disk, or a CD-ROM. Is stored in a viewable format such as MPEG1 or MPEG2.

  Next, the operation of the distance learning system according to the second embodiment will be described with reference to the drawings. FIG. 7 is a flowchart showing an operation of encrypting information communication from the student classroom 3 to the transmission center 1 via the Internet 4 in the distance learning system according to the first embodiment. The information transmission operation of the communication satellite 2 and the Internet 4 is omitted because there is no difference from the operation in the conventional example. Therefore, only the operation of the transmission center 1 and the student classroom 3 is described. However, transmission of lecture video information and digital data from the transmission center 1 to the student classroom 3 is performed via the communication satellite 2 and Transmission of student video information and the like to the transmission center 1 is realized by the respective protocols via the Internet 4.

<Step 1> At the transmission center 1, the information processing means 6 extracts the target student classroom 3a from the student information database 22, activates the key generation means 23, and selects the encryption program 43 from the algorithm database 26. The information of the encryption program 43 selected as one of the attribute information of the student classroom 3a is recorded in the student information database 22.
<Step 2> The key generation means 23 creates a pair of the encryption key 41 and the decryption key 42, and stores the decryption key 42 as one of the attribute information of the student classroom 3a in the student information database 22.
<Step 3> An access key including a password and a connection destination port number for establishing a connection between the transmission center 1 and the student lecture 3 so that the student image information can be transmitted to the transmission center 1 is transmitted to the CPU unit. 21 is created.
<Step 4> The encryption key 41, the encryption program 43, and the access key are distributed to the student classroom selected in Step 2 in a limited manner together with the lecture video information.
<Step 5> The student classroom 3a receives the encryption key 41, the encryption program 43, and the access key by targeted distribution.
<Step 6> The video information connection unit 32 makes a connection request with the transmission center 1 using the simultaneously received access key.
<Step 7> The CPU unit 21 of the transmission center 1 receives the connection request from the student classroom 3a. If the access key of the connection request is the same as the access key created in step 3, the CPU 21 The port is opened to establish a connection with the student classroom 3a.
<Step 8> In the student classroom 3a, the image of the student is captured by the camera 10 on the student side, and the information processing device 9 encodes the image of the student to obtain the student image information, and further uses the encryption key 41. Then, the encryption program 43 is executed and transmitted to the transmission center 1 as encrypted student image information.
<Step 9> The information processing means 6 selects a decryption program 44 corresponding to the encryption program 43 belonging to the student classroom 3a recorded in the student information database 22 from the algorithm database 26, and sets the decryption key 42 The decryption program 44 is used to execute the decryption of the encrypted student video information to obtain student video information.
<Step 10> The transmission center 1 creates lecture video information by synthesizing the student video information from each student classroom 3a selected in step 2 and the video of the lecture taken by the instructor camera 7. , From the transmitting antenna 5 via the communication satellite 2 to all the classrooms.
<Step 11> After the lecture is completed, when the instructor inputs a disconnection instruction from the input unit 25 of the information processing device 6, the information processing unit 6 updates the number of times of the student attribute information in the student information database 22 and the like. Then, an instruction to disconnect the connection is transmitted to the CPU unit 21.
<Step 12> The CPU 21 transmits the connection end instruction data to all the student classrooms, and thereafter closes the port that has received the student image information.
<Step 13> When the connection termination instruction data is received in the student classroom 3, the CPU 31 issues a connection termination instruction to the video information connection means 32 to stop the transmission of the student video information.

  As described above, a method in which the encryption program 43 is selected and transmitted for each communication, and the key generation unit 23 creates a key pair of the encryption key 41 and the decryption key 42 may be used. Alternatively, a method of updating the encryption program 43 and the key pair by repeating Step 1 to Step 10 of selecting and transmitting the encryption program 43 irregularly may be used. It is not necessary to update the encryption program 43 and the key pair at the same time, and only one of them may be updated.

According to the second embodiment of the present invention described above, the encryption program 43 selected on the transmission center 1 side can be targeted and distributed to the student classroom 3a, so that the encryption program 43 is provided for each communication or during the communication period. It is possible to update the key pair by receiving the radio wave from the communication satellite and canceling the scramble by the decoder device in the same manner as in the first embodiment. The confidentiality is enhanced in three stages: only the classroom of the person can obtain the encryption key, and the encryption of the information using the encryption key, and an element of updating the encryption program is added. Therefore, if a third party attempts to eavesdrop on the contents by intercepting the information communication from the student classroom to the transmission center via the Internet, the third party must obtain the secret key from the public key of the public key encryption technology. Even if it can be decrypted, it is difficult to obtain even the encryption key, and furthermore, knowing the algorithm of the encryption program is a consultation, so the confidentiality is greatly improved.
Further, since the encryption key can be transmitted from the transmission center side to the student classroom side, the key generation means generates the encryption key and the decryption key periodically or irregularly, and generates the encryption key. By transmitting the key pair to the student classroom and updating the key pair, confidentiality can be further enhanced.

(Embodiment 3)
In the second embodiment, as the terrestrial network, a telephone line network, an ISDN network, a cable television network, an optical fiber network, communication using a mobile phone, wireless communication, and satellite communication are exemplified, but the exemplified communication method is used alone. Alternatively, a combination of a plurality of them may be used.

  When the above-described distance learning system is constructed by combining a plurality of communication methods, the connection method and the communication method of each of the student classrooms 3 are stored in the student information database 22 included in the information processing means 6 of the transmission center 1. Is recorded, and an encryption program 43 for realizing confidentiality according to the security level of the connection method and the communication method is selected from the algorithm database 26, and is operated in the same manner as step 1 and subsequent steps of the second embodiment.

  By selecting the encryption program 43 in accordance with the communication environment used by the student classroom 3, in a communication environment where information is easily leaked, confidentiality can be maintained even when encryption and decryption take a long time. In the case of a communication environment in which information leakage is difficult, it is possible to select to complete processing in a short time even if confidentiality is relatively low, and a flexible system construction can be performed.

  As an application example of the present invention, application to a remote education system using a communication satellite and a terrestrial network can be considered.

FIG. 1 is a diagram showing a configuration of a distance education system according to the first embodiment. 2 shows a configuration of an information processing apparatus on the transmission center side according to the first embodiment. 3 shows a configuration of an information processing apparatus on the student classroom side according to the first and second embodiments. FIG. 4 is a flowchart showing the operation of the first embodiment. The figure which showed the structure of the distance education system of Embodiment 2. 9 shows a configuration of an information processing apparatus on the transmission center side according to the second embodiment. FIG. 9 is a flowchart showing the operation of the second embodiment. The figure which showed the structure of the conventional distance learning system.

Explanation of reference numerals

1 Transmission center 2 Communication satellite 3 Student classroom 4 Internet 5 Transmission antennas 6 and 9 Information processing device 7 Instructor camera 8 Receiving antenna 10 Student side Cameras 21, 31 CPU part 22 Student information database 23 Key generation means 24, 33 Information storage means 25 Input means 26 Algorithm database 32 Video information connection means 41 Encryption Decryption key 42 decryption key 43 encryption program 44 decryption program

Claims (7)

A communication center between a transmission center having a function of transmitting information to a communication satellite and a function of receiving information from a terrestrial network, and a plurality of student classrooms having a function of transmitting information to the terrestrial network and a function of receiving information from a communication satellite. In a distance education system that performs two-way information transmission with the ground network,
Transmitting an encryption key from the transmission center to the student classroom,
A first information processing device included in the student classroom encrypts digital data using the encryption key to obtain encrypted digital data;
Transmitting the encrypted digital data from the student classroom to the transmission center,
A remote education system, wherein a second information processing device of the transmission center decrypts the encrypted digital data with a decryption key corresponding to the encryption key. A communication center between a transmission center having a function of transmitting information to a communication satellite and a function of receiving information from a terrestrial network, and a plurality of student classrooms having a function of transmitting information to the terrestrial network and a function of receiving information from a communication satellite. In a distance education system that performs two-way information transmission with the ground network,
Transmitting an encryption key and an encryption program from the transmission center to the student classroom,
A first information processing device included in the student classroom encrypts digital data using the encryption key according to the encryption program to obtain encrypted digital data;
Transmitting the encrypted digital data from the student classroom to the transmission center,
2. A remote education system, wherein a second information processing device of the transmission center decrypts the encrypted digital data with a decryption key corresponding to the encryption key according to a decryption program corresponding to the encryption program.   The distance education system according to claim 1, wherein the encryption key and the decryption key are a key pair created by a key generation unit of the second information processing device.   The distance education system according to claim 1, wherein the encryption key and / or the encryption program are updated regularly or irregularly.   The distance education system according to any one of claims 1 to 4, wherein the encryption key and / or the encryption program are transmitted by encrypted targeted distribution.   The said ground network is any one of a telephone line network, an ISDN network, a cable television network, an optical fiber network, communication by a mobile telephone, wireless communication, satellite communication, or a combination thereof. 5. The distance education system according to any one of 5.   7. The remote education system according to claim 1, wherein the encryption program is selected according to a type of the ground network.

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