JP2004349755A - Secret information communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secret information communication system capable of transmitting information whose one part is encrypted to a plurality of communication parties and changing the content to be disclosed depending on the communication parties. <P>SOLUTION: A transmitter communication apparatus has a means by which at least one item of information to be hidden in information to be transmitted is encrypted for each information to be hidden by using the same or different encryption key, and a symbol for allowing a receiver communication apparatus to extract the encrypted information is inserted. Each of the receiver communication apparatuses has a means 1 for extracting the encryption information from the received information on the basis of the symbol, a means 2 for decrypting the encryption information extracted by the means 1, and a means 3 for substituting predetermined information for the encryption information extracted by the means 1 when the encryption information extracted by the means 1 cannot be decrypted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a confidential information communication system, and more particularly to a confidential information communication system for performing data communication in which a part of information is encrypted.
[0002]
[Prior art]
FIG. 13 is a diagram illustrating a conventional data communication system.
As shown in the figure, a plurality of communication terminals (10, 20, 30) are connected via a data communication network 50.
The message to be transmitted is input as a data signal from the transmitting communication terminal 10 to the data communication network 50, and the data communication network 50 transfers the data signal to the receiving communication terminals (20, 30). The receiving communication terminals (20, 30) that have received the data signal output the data signal as a communication message.
Here, when it is desired to hide some information in the message to a part of the communication terminal on the receiving side, for example, the entire content of the message is stored in the communication terminal 20 and a part of the text is stored in the communication terminal 30. (Here, “Yamada”) wants to face down.
In this case, the sender separately creates two messages (messages A and A ′ shown in FIG. 13) and transfers the messages to the respective communication terminals (20, 30).
The communication terminal 20 that has received the data recognizes the entire message (message B shown in FIG. 13), and the communication terminal 30 recognizes the message as message C with the information of “Yamada” hidden (message C shown in FIG. 13). can do.
FIG. 14 is a block diagram showing a schematic configuration of the communication terminal shown in FIG.
The communication terminal 10 on the transmission side includes a data input / output unit 11 and a data transmission unit 12 for transmitting an input message to the data communication network 50 as data. The data input / output unit 11 has a data input unit (not shown) for the user 100 to input a message and a data output unit (not shown) for confirming the input content.
The communication terminals (20, 30) on the receiving side receive the data transferred from the data communication network 50, and the user 101 confirms the data received by the data receiving means 22 as a communication message. Data input / output means 21.
[0003]
Prior art documents related to the present invention include the following.
[Non-patent statement]
OpenPGP http: // www. openpgp. org /
[0004]
[Problems to be solved by the invention]
As described above, in the related art, when the content to be disclosed is changed according to the communication partner, a communication message (a communication message with no hidden information and a communication message with the information hidden) is prepared and transmitted for each communication partner. There is a problem that it is necessary and time-consuming.
The present invention has been made in order to solve the problems of the conventional technology, and an object of the present invention is to encrypt a part of information, transmit the encrypted information to a plurality of communication partners, and disclose the information according to the communication partners. An object of the present invention is to provide a confidential information communication system whose contents can be changed.
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0005]
[Means for Solving the Problems]
The following is a brief description of an outline of typical inventions disclosed in the present application.
The present invention is a confidential information communication system in which information to be concealed according to each receiving communication device exists in information transferred to a plurality of receiving communication devices, and the transmitting communication terminal (or , The server) encrypts the at least one piece of information to be concealed in the information to be transmitted for each of the at least one piece of information to be concealed, using the same or different encryption key, and receives the encrypted information. A symbol for enabling extraction in the communication device on the side is inserted, and the communication device on the receiving side extracts the cryptographic information from the information received based on the symbol and decrypts the cryptographic information, or decrypts the extracted cryptographic information. When the encryption cannot be performed, the extracted encryption information is replaced with predetermined information.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and repeated description thereof will be omitted.
[Embodiment 1]
FIG. 1 is a block diagram showing a schematic configuration of the secret information communication system according to the first embodiment of the present invention.
As shown in the figure, a plurality of communication terminals (10, 20, 30) are connected via a data communication network 50.
The message to be transmitted is input as a data signal from the transmitting communication terminal 10 to the data communication network 50, and the data communication network 50 transfers the data signal to the receiving communication terminals (20, 30).
The receiving communication terminals (20, 30) that have received the data signal output the data signal as a communication message.
Here, it is assumed that there is information to be hidden by a receiving communication terminal for a part of the information of the communication message. For example, it is assumed that the communication terminal 20 wants to hide the entire contents of the message and the communication terminal 30 wants to hide a part of the sentence (here, “Yamada”).
[0007]
According to the present invention, the sender specifies a place to be hidden using a special symbol when creating a message.
In the present embodiment, a character is designated by enclosing both ends of a character to be made into a character with the symbols <a character S> and a <a character E> (message A shown in FIG. 1).
The sender encrypts the hidden part of the message (for example, refer to Non-patent Document 1) (processing of 60 in FIG. 1), and transfers the message to the communication terminal 20 and the communication terminal 30 on the receiving side. .
Since the communication terminal 20 has the decryption key, the secret character is decrypted using the decryption key (the processing of 61 shown in FIG. 1), whereby all the messages (message B shown in FIG. 1) are obtained. Can be recognized.
On the other hand, since the communication terminal 30 does not have the decryption key, the encrypted portion is recognized as a hidden character (the process of 62 shown in FIG. 1).
[0008]
FIG. 2 is a block diagram showing a schematic configuration of the communication terminal (10, 20, 30) shown in FIG.
The communication terminal 10 on the transmitting side includes a data input / output unit 11, a hidden character encryption processing unit 13 for encrypting a hidden character portion from an input communication message, an encryption key table 14 for performing encryption, And a data transmission unit 12 for transferring the sent communication data as data to a data communication network. The data input / output means 11 has a data input means for inputting a message from the user 100 and a data output means for prompting confirmation of the input message.
As shown in FIG. 2B, the communication terminal 10 on the transmitting side may include a communication text editing unit 15 between the data input / output unit 11 and the hidden character encryption processing unit 13.
The receiving communication terminals (20, 30) include a data receiving unit 22 for receiving data from the data communication network 50, and a secret character decryption processing unit 23 for decrypting an encrypted area in the received data. And a decryption key table 24 for performing decryption, and a data input / output unit 21 for displaying the decrypted message.
[0009]
FIG. 3 is a flowchart for explaining a processing procedure of the encryption processing and the decryption processing according to the present embodiment.
First, a procedure for creating an encrypted message by the communication terminal 10 on the transmitting side will be described.
The hidden character encryption processing unit 13 of the communication terminal 10 on the transmitting side checks the presence or absence of the hidden character in the input communication message (the communication message A shown in FIG. 3). The information of the area specified by is extracted (step 201).
The extracted information (here, “Yamada”) is encrypted using the encryption key of the encryption key table 14 (step 202).
In this encryption, character string conversion is performed using a function F (character string, encryption key) (here, “YZQMLS” is an encrypted character string).
The encrypted character string is replaced with the character string of the original message (here, “Yamada” is replaced with “YZQMLS”) to create a message to be transmitted (step 203).
Next, a procedure for creating a decrypted message by the communication terminal 20 on the receiving side will be described.
The hidden character decoding processing unit 23 of the communication terminal 20 examines the received communication message (the communication message Ad shown in FIG. 3) for the presence or absence of the hidden character, and when the hidden character exists, the hidden character is designated by the hidden character. (Here, "YZQMLS") is extracted (step 211).
The extracted information is restored using the held decryption key (the decryption key in the decryption key table 24) (step 212). Here, an example is shown in which decryption is performed using the decryption function G (character string, decryption key).
The replaced message (message B shown in FIG. 3) is presented to the user by the data input / output unit 21.
[0010]
Next, a description will be given of a procedure for creating a communication sentence of the communication terminal 30 on the receiving side.
The hidden character decoding processing unit 23 of the communication terminal 30 examines the received communication message (the communication message Ad shown in FIG. 3) for the presence or absence of the hidden character, and when the hidden character exists, the character is designated by the hidden character. (Here, "YZQMLS") is extracted (step 221).
Since the communication terminal 30 does not hold the decryption key, it replaces the extracted information with appropriate information (step 222). Here, an example is shown in which substitution is made with the symbol “xx”.
The replaced message (message C shown in FIG. 3) is presented to the user by the data input / output unit 21.
It is also conceivable to specify an encryption level when encrypting a hidden character, and to encrypt with a different encryption key for each level.
For example, different encryption keys can be used by separately describing the abbreviated symbols such as <abbreviated S, level 1><abbreviated E, level 1> and <abbreviated S, level 2><abbreviated E, level 2>. Can be distinguished.
Also, at the time of decryption, it is possible to perform decryption using a decryption key corresponding to each level.
[0011]
[Embodiment 2]
FIG. 4 is a block diagram illustrating a schematic configuration of a secret information communication system according to Embodiment 2 of the present invention. This embodiment is an embodiment in which encryption and communication are performed via a server 40.
As shown in the figure, a plurality of communication terminals (10, 20, 30) and a server 40 are connected via a data communication network 50.
The message to be transmitted is input as a data signal from the communication terminal 10 on the transmission side to the server 40 from the data communication network 50. The server 40 transmits the data signal via the data communication network 50 to the communication terminal (20, Transfer to 30).
Here, it is assumed that some information of the communication message includes information that the communication terminal on the receiving side wants to hide. For example, it is supposed that the entire contents of the message are to be hidden by the communication terminal 20 on the receiving side, and a part of the sentence (here, “Yamada”) is to be hidden by the communication terminal 30 on the receiving side.
The sender uses a special symbol to designate a part to be made lowercase when creating a message. In the present embodiment, a communication message (a communication message A shown in FIG. 4) in which a character is designated is created by enclosing both ends of a character to be made a character with the symbols <a character S> and <a character E>. This message is transferred to the server 40.
The server 40 encrypts the hidden part of the received message and transfers the message to the communication terminals 20 and 30.
The communication terminal 20 having the decryption key decrypts the hidden character and displays a message (message B shown in FIG. 4). On the other hand, the communication terminal 30 having no decryption key displays a message (message C shown in FIG. 4) in which the encrypted part is replaced with appropriate information (here, the symbol “xx”).
[0012]
FIG. 5 is a block diagram showing a schematic configuration of the communication terminals (10, 20, 30) and the server 40 according to the present embodiment.
The communication terminal 10 on the transmission side includes a data input / output unit 11 and a data transmission unit 12 for transmitting an input message to the data communication network 50 as data. The data input / output unit 11 includes a data input unit (not shown) for inputting a communication sentence from the user 100 and a data output unit (not shown) for displaying an input result.
The server 40 includes a data receiving unit 41 for receiving data from the data transfer network 50, a hidden character encryption processing unit 43 for encrypting a hidden character portion of the received data, and a data necessary for executing an encryption process. An encryption key management table 44 for storing an encryption key, a data stock unit 45 for storing an encrypted communication message, and a data transmission unit 42 for transferring the encrypted communication message as data to a data communication network 50 are provided.
The receiving communication terminals (20, 30) include a data receiving unit 22 for receiving data from the data communication network 50, and a secret character decryption processing unit 23 for decrypting an encrypted area in the received data. And a decryption key table 24 for performing decryption, and a data input / output unit 21 for displaying the decrypted message.
[0013]
[Embodiment 3]
FIG. 6 is a block diagram illustrating a schematic configuration of a secret information communication system according to Embodiment 3 of the present invention. This embodiment is also an embodiment in which encryption and communication are performed via the server 40.
As shown in the figure, a plurality of communication terminals (10, 20, 30, 70) and a server 40 are connected via a data communication network 50.
The message to be transmitted is input as a data signal from the communication terminal 10 on the transmission side to the server 40 from the data communication network 50. The server 40 transmits the data signal via the data communication network 50 to the communication terminal (20, 30, 70).
In the present embodiment, the sender transmits a message (message A shown in FIG. 6) to server 40 without being conscious of the hidden letter.
The server 40 analyzes the sentence of the received communication message and determines a part to be turned into a hidden character. For example, a proper noun is extracted and the encryption level is determined (here, the case where the station name “Shibuya Station” is level 1 and the personal name “Yamada” is level 2 is shown).
Based on the hidden part and the encryption level, the hidden part is encrypted and an encrypted message is created.
[0014]
In the present embodiment, the characters <invisible S, level n> and <invisible E, level n> are used to enclose both ends of the character to be made invisible, so that the invisible character and the encryption level can be distinguished.
The encrypted message (message Ad shown in FIG. 6) is transmitted from the server 40 to each communication terminal (20, 30, 70) on the receiving side, and is decrypted by each communication terminal (20, 30, 70). Is done.
Each terminal on the receiving side decrypts only the portion corresponding to the held key, and the communication terminal having no key displays the encrypted portion as a hidden character.
In FIG. 6, since the communication terminal 20 has the decryption key of each level, all of the messages (message B shown in FIG. 6) are displayed.
Further, since the communication terminal 30 has the level 1 decryption key and does not have the level 2 decryption key, the communication message (in this case, “Yamada”) encrypted at the level 2 is invisible. The message C) shown in FIG. 6 is displayed.
Further, since the communication terminal 70 does not have the decryption key of level 1 and the decryption key of level 2, the encrypted message (here, “Shibuya station” and “Yamada”) is hidden. (Message D shown in FIG. 6) is displayed.
[0015]
FIG. 7 is a block diagram illustrating a schematic configuration of the communication terminals (10, 20, 30, and 70) and the server 40 according to the present embodiment.
The communication terminal 10 on the transmission side includes a data input / output unit 11 and a data transmission unit 12 for transmitting an input message to the data communication network 50 as data. The data input / output unit 11 includes a data input unit (not shown) for inputting a communication sentence from the user 100 and a data output unit (not shown) for displaying an input result.
The server 40 includes a data receiving unit 41 for receiving data from the data transfer network 50, an expert system 46 for determining a hidden part and an encryption level of the received data, and a secret encryption processing for encrypting a secret part. Unit 43, an encryption key management table 44 for storing an encryption key required to execute an encryption process, a data stock unit 45 for storing an encrypted communication message, and data communication using the encrypted communication message as data. Data transmission means 42 for transferring the data to the network 50.
The receiving communication terminal (20, 30, 70) includes a data receiving unit 22 for receiving data from the data communication network 50 and a decryption process for decrypting an encrypted area in the received data. A unit 23, a decryption key table 24 for performing decryption, and a data input / output unit 21 for displaying a decrypted message.
FIG. 8 shows the contents of the encryption key management table 44 and the decryption key table 24 according to the present embodiment.
[0016]
FIG. 9 is a flowchart for describing the processing procedure of the encryption processing and the decryption processing according to the present embodiment.
First, a procedure of the server 40 for creating an encrypted message will be described.
The expert system 46 of the server 40 extracts proper nouns and the like from the input message (message A shown in FIG. 9) and assigns encryption levels (step 231). Here, "Shibuya Station" is at level 1 and "Yamada" is at level 2.
It should be noted that the expert system 46 may randomly determine the hidden part and the encryption level.
The secret character encryption processing unit 43 encrypts the extracted information (here, “Shibuya Station” and “Yamada”) using the encryption key of the corresponding level (the encryption key in the encryption key management table 44). (Step 232).
In this encryption, character string conversion is performed using a function F (character string, encryption key). Here, “MMG” and “YZQMLS” are encrypted character strings.
The encrypted character string is replaced with the character string of the original message (here, "Shibuya Station" is replaced with "MMG", "Yamada" is replaced with "YZQMLS"), and the abbreviation symbol (here, <Face S, Level 1><Face E, Level 1> or <Face S, Level 2><Face E, Level 2>) is inserted (step 233), and the message to be transmitted (shown in FIG. 9) Create a message Ad).
[0017]
Next, a procedure for creating a communication message of each communication terminal on the receiving side will be described.
The hidden character decoding processing unit 23 of the communication terminal 20 first examines the received message for the presence or absence of a symbol, and if there is a symbol, extracts information of an area designated by the symbol (step 241).
Since the communication terminal 20 has the level-1 and level-2 decryption keys, the extracted encryption information (here, "MMG", "YZQMLS") is stored in the corresponding level decryption key (decryption key table 24). (Step 242), and replaces the input document with the restored character string (Step 243). Here, an example is shown in which decryption is performed using the decryption function G (character string, decryption key).
The replaced message (message B shown in FIG. 9) is presented to the user by the data input / output unit 21.
The hidden character decoding processing unit 23 of the communication terminal 30 first examines the received message for the presence or absence of a symbol, and if there is a symbol, extracts information of an area specified by the symbol (step 251).
Since the communication terminal 30 has the level 1 decryption key and does not have the level 2 decryption key, it decrypts the “MMG” portion in the extracted encrypted information using the corresponding level decryption key. And replace the "YZQMLS" part with appropriate information (here, symbol "xx") (step 252). Here, an example is shown in which decryption is performed using the decryption function G (character string, decryption key).
[0018]
Next, the input document is replaced with the restored character string or an appropriate symbol (step 253).
The replaced message (message C shown in FIG. 9) is presented to the user by the data input / output unit 21.
The hidden character decoding processing unit 23 of the communication terminal 70 first checks the received message for the presence or absence of a symbol, and if there is a symbol, extracts information of an area specified by the symbol (step 261).
Since the communication terminal 70 does not have the level 1 and level 2 decryption keys, it replaces the “MMG” portion of the extracted encrypted information with appropriate information (here, the symbol “△△”), and , "YZQMLS" are replaced with appropriate information (here, symbol "xx") (step 262).
The replaced message (message D shown in FIG. 9) is presented to the user by the data input / output unit 21.
In the present embodiment, the level of the decryption key held for each user is different, but this may be such that the server 40 automatically manages the distribution via the data communication network 50 with some agreement for each user. Alternatively, the server administrator may notify by another information transfer means.
[0019]
[Embodiment 4]
Each of the embodiments described above is an example of a sentence. However, for example, it is possible to deal with still image information, moving image information, and audio information.
The case of transmitting a still image will be described with reference to FIG.
In the communication terminal on the transmission side, a part 301 of the original image 300 is concealed by a mosaic technique or the like (processing 310 in FIG. 10), and an image of a video 301 to be concealed (confidential information in FIG. 10) 301 is cut out (FIG. 10). (Step 311 in FIG. 10), encrypts the data (Step 313 in FIG. 10), and further obtains position information of the extracted image with respect to the original image (Step 312 in FIG. 10).
Then, three pieces of information of the position information of the cut-out image with respect to the original image, the encrypted image 303 of the cut-out image, and the mosaiced image 302 are collectively transmitted to the communication terminal on the receiving side.
The receiving communication terminal decrypts the encrypted image (process 331 in FIG. 10), specifies the position based on the position information (process 332 in FIG. 10), and superimposes the image on the mosaiced image. Thus, the original image 305 is restored.
Next, the case of transmitting a moving image will be described with reference to FIG.
The communication terminal on the transmitting side selects the video 301 to be concealed from the original image 300, conceals the image at that time by, for example, a mosaic technique (process 310 in FIG. 11), and cuts out the video to be concealed. (Process 311 in FIG. 11), encrypts (Process 313 in FIG. 11), and further obtains time information of an image cut out from the original image (Process 312 in FIG. 11).
[0020]
Then, the time information of the image cut out from the moving image, the encrypted moving image 303, and the mosaiced moving image 302 are transmitted to the communication terminal on the receiving side.
The communication terminal on the receiving side decrypts the encrypted moving image (process 331 in FIG. 11), specifies the position based on the time information (process 332 in FIG. 11), and overlaps the mosaiced moving image. Thus, the original image 305 is restored.
Next, a case of transmitting voice will be described with reference to FIG.
In the communication terminal on the transmitting side, the voice 351 to be concealed is selected from the original voice 350, and the voice at that time is concealed by, for example, silence (process 360 in FIG. 12), and the voice to be concealed. (Process 361 in FIG. 12), encrypts it (process 363 in FIG. 12), and obtains time information of the voice cut out from the original voice (process 362 in FIG. 12).
Then, the time information of the voice cut out from the original voice, the encrypted voice 353, and the voice 352 subjected to the silence are transmitted to the communication terminal on the receiving side.
In the communication terminal on the receiving side, the encrypted voice is decrypted (process 361 in FIG. 12), the position is specified based on the time information (process 362 in FIG. 12), and the voice is superimposed on the muted voice. Thus, the original voice 355 is restored.
[0021]
According to the present embodiment, the sender does not need to create a message for each recipient, and only has to create one message specifying the encryption level of the hidden character.
In addition, the receiver can confirm the message by decrypting the encrypted hidden character portion in accordance with the held decryptable level, so that the hidden character communication can be easily performed. Become.
Each of the above-described embodiments can be applied to, for example, a campaign for pay information (TVCD, photo book).
For example, a recovery key is sent to a user who has already paid a fee in advance. A user who has not paid the fee can view a moving image in which some information is concealed.
In this way, the user who has listened and purchased the sample can be browsed by newly assigning a restoration key.
In addition, each of the above-described embodiments can be applied to, for example, browsing of company information.
By setting the decryption level according to the position of the user and distributing the decryption key in advance, it is possible to view information that can be browsed according to the position.
As described above, the invention made by the inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and can be variously modified without departing from the gist of the invention. Needless to say,
[0022]
【The invention's effect】
The following is a brief description of an effect obtained by a representative one of the inventions disclosed in the present application.
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to encrypt a part of information and transmit it to several communication partners, and to change the disclosed content according to a communication partner.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of a secret information communication system according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a schematic configuration of the communication terminal shown in FIG.
FIG. 3 is a flowchart illustrating a processing procedure of an encryption process and a decryption process according to the first embodiment of the present invention.
FIG. 4 is a block diagram illustrating a schematic configuration of a secret information communication system according to a second embodiment of the present invention.
FIG. 5 is a block diagram illustrating a schematic configuration of a communication terminal and a server according to a second embodiment of the present invention.
FIG. 6 is a block diagram illustrating a schematic configuration of a secret information communication system according to a third embodiment of the present invention.
FIG. 7 is a block diagram illustrating a schematic configuration of a communication terminal and a server according to a third embodiment of the present invention.
FIG. 8 is a diagram showing contents of an encryption key management table and a decryption key table according to the third embodiment of the present invention.
FIG. 9 is a flowchart illustrating a procedure of an encryption process and a decryption process according to the third embodiment of the present invention.
FIG. 10 is a diagram illustrating a secret information communication system according to a fourth embodiment of the present invention, and is a diagram illustrating a case where a still image is transmitted.
FIG. 11 is a diagram illustrating a secret information communication system according to a fourth embodiment of the present invention, and is a diagram illustrating a case where a moving image is transmitted.
FIG. 12 is a diagram illustrating a confidential information communication system according to a fourth embodiment of the present invention, and is a diagram illustrating a case where voice is transmitted.
FIG. 13 is a diagram illustrating a conventional data communication system.
FIG. 14 is a block diagram showing a schematic configuration of the communication terminal shown in FIG.
[Explanation of symbols]
10, 20, 30, 70: communication terminal, 11, 21: data input / output unit, 12, 42: data transmission unit, 13, 43: hidden character encryption processing unit, 14: encryption key table, 15: communication text editing unit , 22, 41 ... data receiving means, 23 ... secret character decryption processing unit, 24 ... decryption key table, 40 ... server, 44 ... encryption key management table, 45 ... data stock unit, 46 ... expert system, 50 ... data communication network , 100, 101: user, 300: original image, 301: part of the original image, 302: mosaiced image, 303: encrypted image, 305: restored original image, 350: original sound, 351 ... Part of the original sound, 352: silenced sound, 353: encrypted sound, 355: restored original sound.

Claims (3)

A transmitting communication device;
A plurality of receiving communication devices;
A data communication network to which the transmitting communication device and the plurality of receiving communication devices are connected,
A confidential information communication system in which information to be concealed in accordance with the individual receiving communication devices exists in information transferred from the transmitting communication device to the plurality of receiving communication devices,
The transmission-side communication device encrypts the at least one information to be concealed in the information to be transmitted, for each of the at least one piece of information to be concealed, using the same or different encryption key, and encrypts the encrypted information. Means for inserting a symbol for enabling extraction in the receiving communication device,
Means for extracting encryption information from received information based on the symbols,
Means 2 for decrypting the encrypted information extracted by said means 1,
Means for replacing the encrypted information extracted by the means with predetermined information when the encrypted information extracted by the means cannot be decrypted. A transmitting communication device;
A plurality of receiving communication devices;
Server and
The transmission-side communication device, the plurality of reception-side communication devices, and a data communication network to which the server is connected,
A confidential information communication system in which information to be concealed according to each of the receiving communication devices exists in information transferred from the transmitting communication device to the plurality of receiving communication devices via a server. hand,
The transmission-side communication device has means for inserting a symbol for allowing the server to extract the at least one information to be concealed in the transmitted information,
The server has, based on the symbol, extracts at least one piece of information to be concealed in information transmitted from the transmitting communication device, and has means for encrypting using the same or different encryption key.
Means for extracting encryption information from received information based on the symbol,
Means 2 for decrypting the encrypted information extracted by said means 1,
Means for replacing the encrypted information extracted by the means with predetermined information when the encrypted information extracted by the means cannot be decrypted. A transmitting communication device;
A plurality of receiving communication devices;
Server and
The transmission-side communication device, the plurality of reception-side communication devices, and a data communication network to which the server is connected,
A confidential information communication system in which information to be concealed according to each of the receiving communication devices exists in information transferred from the transmitting communication device to the plurality of receiving communication devices via a server. hand,
Means for automatically extracting the at least one piece of information to be concealed in information transmitted from the transmitting side communication device,
Means 12 for encrypting each of the at least one information extracted by the means 11 using the same or different encryption key, and inserting a symbol for enabling the encrypted information to be extracted in the receiving communication device; Have
Said receiving side communication device, based on the symbol, means 21 for extracting encrypted information from the received information,
Means 22 for decrypting the encryption information extracted by said means 21;
Means for replacing the encrypted information extracted by the means with predetermined information when the encrypted information extracted by the means cannot be decrypted.

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