JP4875526B2 - Security program and server - Google Patents

Description

  The present invention relates to information security technology, and more particularly, to information processing technology for ensuring confidentiality and anonymity of communication.

In a computer network using the Internet, communication between a plurality of computers is usually performed by interposing one or more network devices called routers or switches. These network devices such as routers and switches have a log function for recording communication between computers, each identification number, the time of communication, and information on a simple program.
If the log information recorded by the log function is analyzed, the communication history can be traced.

  Japanese Unexamined Patent Application Publication No. 2007-34651 is known as a technique for ensuring confidentiality on a network. This technology makes it possible to prevent personal information and confidential information from being taken out and transmitted from each terminal to the outside in a state where everyone can refer to it. This is a technology to reliably prevent spills, leaks and unauthorized use.

JP 2007-34651 A

On the other hand, if a third party can access the log information of the network devices such as the router and the switch, the communication history can be traced. For this reason, it is not suitable for communications that require high confidentiality. In addition, there is a demand to prevent identification of a user (computer) that has transmitted a file, and ensuring the anonymity of the sender has also been a problem.
In addition, although the technique of patent document 1 describes the prevention technique with respect to information leakage, the technique which solves the said subject is not disclosed.

Therefore, the problem to be solved by the present invention is to provide a technique capable of ensuring the confidentiality of communication between computers and the anonymity of the sender.
The object of the invention described in claims 1 to 5 is to provide a computer program capable of ensuring confidentiality and anonymity of communication between computers.
The object of the invention described in claims 6 to 11 is to provide a server capable of ensuring confidentiality and anonymity of communication between computers.

In the present invention, by transmitting genuine data (real data) and its dummy data, the real data cannot be specified from the outside, thereby enhancing the confidentiality of information and ensuring the sender's anonymity. To do.

(Claim 1)
The invention according to claim 1 is installed in a plurality of terminal devices participating in a group created in advance according to a predetermined arrangement, and only the terminal device designated as a receiver of real data can receive the real data. Provided security programs.
The program includes a group public key transmission procedure for transmitting a group public key that can be acquired by a terminal device authenticated as a group user, a receiving terminal designated as a real data receiver, and a transmitting side for transmitting real data. A dummy packet transmission procedure which is shared as a personal public key with the terminal and which functions as a dummy by broadcast transmission to the other terminal devices in the group; and the real data and the real data are data A first encryption procedure for encrypting transmission data created from dummy data having the same structure; a second encryption procedure for further encrypting the transmission data encrypted by the first encryption procedure; The transmission data encrypted by the second encryption procedure is run from a plurality of terminal devices in the group. The computer can execute a random transmission procedure in which the dumb is selected and transmitted.
Also, a decoding determination for determining whether or not a predetermined terminal device that has received transmission data transmitted by a random transmission procedure executed by another terminal device related to the group can decode the transmission data. A dummy packet that randomly transmits encrypted data for transmission from the terminal device to another terminal device when real data can be extracted from the data for transmission received by the procedure and the decryption determination procedure This is a security program that causes a computer to execute a transmission procedure.

(Glossary)
The “terminal device” is a terminal device related to a user, such as a personal computer, a workstation, a PDA, or a mobile phone.
A “group” is created between a sender and a receiver that exchange real data, and restricts access from outside the group by sharing a group public key.
The “dummy packet” means that the receiving side terminal designated as the receiver of the real data shares it with the transmitting side terminal as a personal public key. On the other hand, other receiving side terminals (non-receiving side terminals) also receive the same dummy packet, but are not receivers of real data and can only receive them as dummy. On the surface, the same data structure is flowing over the network.

“Transmission data” is data composed of real data or dummy data. Whether real data or dummy data is determined is determined by a hash value or the like.
“Random transmission” is a process of randomly selecting all the terminal devices in the group and transmitting data for transmission. Since the transmission data is double-encrypted, it cannot be received by terminals other than those designated as real data receivers.
“Dummy packet random transmission” is a process in which random transmission is continuously repeated even after the reception side terminal normally receives real data. It should be noted that it is desirable to appropriately set how long this repetitive process is continued, and in this way, network congestion can be prevented.

(Function)
This is a process in a case where “transmission data” randomly transmitted from the transmission side terminal is received by a legitimate reception side terminal designated in advance.
First, the group public key and the personal public key are shared. The group public key is transmitted to all terminal devices participating in the group. The personal public key is shared only by the receiver (reception side terminal) that has joined the group and specified by the sender of the real data. That is, to acquire real data, two keys, a group public key and an individual public key, are required.

This personal public key is broadcasted to the intra-group network. This can be opened only by the receiving terminal, but also functions as dummy data by transmitting to other terminal devices. In this way, a certain level of security is maintained by periodically transmitting dummy packets within the group.
The first encryption procedure creates real data and dummy data as “transmission data” and encrypts them. The first encryption procedure creates a common key and encrypts it with the common key and the recipient's public key. Since the dummy data has the same data structure as that of the real data, it cannot be distinguished from the outside and contributes to the improvement of confidentiality.

Subsequently, the “transmission data” encrypted by the first encryption procedure is further encrypted by the second encryption procedure. In the second encryption procedure, encryption is performed with the group common key and the group public key.
The encrypted “transmission data” is randomly transmitted to all terminal devices in the group.
Here, when the terminal device that has received the “transmission data” is the terminal device designated as the receiver, the decoding is successful. When real data is obtained by decryption, it is encrypted again and “transmission data” is randomly transmitted to other terminal devices.

  That is, by constantly transmitting dummy packets on the intra-group network, it becomes difficult to identify the sender itself, and anonymity is ensured. Even the most important real data cannot be obtained because there is no key necessary for decryption other than the receiving terminal which is a valid terminal device designated in advance by the sender. In addition, it is difficult to identify senders and receivers from outside by ensuring random transmission to other terminal devices in the same way without ending the processing after acquiring real data, and ensuring anonymity. Contributes to

(Claim 2)
The invention according to claim 2 is installed in a plurality of terminal devices participating in a group created in advance according to a predetermined arrangement, and only the terminal device designated as a receiver of real data can receive the real data. Provided security programs.
The program includes a group public key transmission procedure for transmitting a group public key that can be acquired by a terminal device authenticated as a group user, a receiving terminal designated as a real data receiver, and a transmitting side for transmitting real data. A dummy packet transmission procedure which is shared as a personal public key with a terminal and which functions as a dummy by broadcast transmission to other terminal devices in the group; and the real data and the real data are data A first encryption procedure for encrypting transmission data created from dummy data having the same structure; a second encryption procedure for further encrypting the transmission data encrypted by the first encryption procedure; The transmission data encrypted by the second encryption procedure is run from a plurality of terminal devices in the group. The computer executes a random transmission procedure for selecting and transmitting the dumb.
Also, a decoding determination procedure for determining whether or not a predetermined terminal device that has received the transmission data transmitted by the random transmission procedure executed by another terminal device related to the group can decode the transmission data. And a dummy packet random transmission procedure for randomly transmitting transmission data from the terminal device to another terminal device when real data cannot be extracted from the transmission data received by the decoding determination procedure, A security program to be executed by a computer.

(Function)
The present invention is a process when the “transmission data” randomly transmitted from the transmission side terminal is received by a non-reception side terminal other than the legitimate reception side terminal specified in advance. That is, if it is transmitted at random, the probability that “data for transmission” will be transmitted to the receiving terminal at a time is low.
The difference from the processing of claim 1 is that when the non-receiving side terminal receives the “transmission data”, the real data cannot be extracted from the “transmission data” transmitted from the transmission side terminal. Even in this case, “transmission data” is set to be randomly transmitted to other terminal apparatuses. This makes it possible to ensure anonymity and confidentiality from a third party by always repeating the same process regardless of whether or not real data is acquired.

(Claim 3)
The invention according to claim 3 limits the security program according to claim 1 or claim 2.
That is, the dummy packet is formed with the same data structure as the real data.

(Function)
If the dummy packet has the same data structure as the real data, the dummy data having the same data structure as the real data will overflow on the intra-group network. For this reason, confidentiality can be improved.

(Claim 4)
The invention according to claim 4 limits the security program according to any one of claims 1 to 3.
That is, the first encryption procedure, a common key generation procedure for creating a common key, a common key encryption procedure for encrypting the transmission data with the common key, the common key, the recipient terminal A public key encryption procedure for encrypting with the created personal public key, and a concatenated data creation procedure for concatenating the personal public key, the encrypted common key, and the encrypted transmission data as one data. It is characterized by having.

(Function)
The first encryption procedure will be described with reference to FIG. 7 and corresponds to encryption α.
That is, the group child (1) corresponding to the transmission side terminal creates the common key (1) (common key creation procedure), and encrypts the data for transmission using the common key (1) (common key encryption procedure). .
Subsequently, the created common key (1) is obtained from the group child (2) corresponding to the receiving side terminal and encrypted with the personal public key [2] (public key encryption procedure).
Then, the personal public key [2], the encrypted common key (1 ′), and the encrypted transmission data are concatenated as one data (concatenated data creation procedure).

(Claim 5)
The invention according to claim 5 limits the security program according to claim 4 .
That is, the second encryption procedure includes a second common key creation procedure for creating a second common key and a concatenated data for encrypting the concatenated data using the second common key created in the second common key creation procedure. An encryption procedure, a group public key encryption procedure for encrypting the encrypted second common key with the group public key G, the group public key G, the encrypted second common key and the encryption A second concatenated data creation procedure for concatenating the transmission data into a single piece of data.

(Function)
The second encryption procedure will be described based on FIG. 7 and corresponds to encryption β.
First, the group child (1) corresponding to the transmitting terminal creates a common key (g) (second common key creation procedure), and encrypts the concatenated data using the created common key (g) (concatenated data encryption). Procedure). Subsequently, the common key (g) is encrypted with the group public key G (group public key encryption procedure).
Then, the group public key G, the encrypted common key (g ′), and the encrypted transmission data are concatenated as one data (second concatenated data creation procedure).
These encrypted data are concatenated to form concatenated data, and the data structure of the concatenated data is composed of a group public key G, an encrypted common key (g ′) and encrypted transmission data. That is, since the concatenated data encrypted by the encryption α is further encrypted by the encryption β, the security of “transmission data” is improved.

  The computer program according to any one of claims 1 to 5 can be provided by being stored in a recording medium. Here, the “recording medium” is a medium that can carry a program that cannot occupy space by itself. For example, a flexible disk, hard disk, CD-R, CD-RW, MO (magneto-optical disk), DVD ± R, DVD-RW, flash memory, and the like. It is also possible to transmit from a computer storing the program according to the present invention to another terminal device through a communication line.

(Claim 6)
According to a sixth aspect of the present invention, there is provided a server characterized in that the security program according to the first aspect can be used by being connected to each terminal device via the Internet or an intranet.

(Function)
The above-described security program is installed and operating in a storage medium such as a hard disk of each terminal device, and this function is provided by a client-server type. That is, each terminal device can be operated by connecting to a server via the Internet or an intranet and installing a security program.
According to the present invention, even if the security program is not installed in the terminal device used by the user, the operation becomes possible, so that the user can use it without selecting a place. For this reason, versatility increases.

(Claim 7)
According to a seventh aspect of the present invention, there is provided a server characterized in that the security program according to the second aspect can be used by connecting the terminal devices via the Internet or an intranet.

(Claim 8)
According to an eighth aspect of the present invention, there is provided a server characterized in that the security program according to the third aspect can be used by connecting the terminal devices via the Internet or an intranet.

(Claim 9)
According to a ninth aspect of the present invention, there is provided a server characterized in that the security program according to the fourth aspect can be used by connecting each terminal device via the Internet or an intranet.

(Claim 10)
According to a tenth aspect of the present invention, there is provided a server characterized in that the security program according to the fifth aspect can be used by connecting the terminal devices via the Internet or an intranet.

(Claim 11)
The invention according to claim 11 limits the server according to any one of claims 6 to 10.
In other words, the server can be used as an application service provider.

(Function)
Each terminal device uses web browser software in an environment connected to the Internet, accesses a server of an application service provider (hereinafter referred to as ASP), and is provided with a security program from the ASP.
Each terminal device can be used as long as it has an Internet usage environment and web browser software, so that system management, for example, when used internally, becomes easy.
In general, the usage is based on a contract such as a rental system.
When used as an ASP type, it can also be used as a trial before implementing security programs or as a test operation.

According to the first to fifth aspects of the invention, a computer program capable of ensuring the confidentiality and anonymity of communication between computers can be provided.
According to the invention described in claims 6 to 11, a server capable of ensuring confidentiality and anonymity of communication between computers can be provided.

  Hereinafter, the present invention will be described in more detail based on embodiments and drawings. The drawings used here are FIGS. 1 to 10. FIG. 1 is a conceptual diagram schematically showing the flow of data between grouped terminal devices, and FIGS. 2 and 3 are block diagrams showing the hardware configuration of each terminal device. FIG. 5 is a flowchart showing data transmission between terminal devices, FIG. 5 is a flowchart showing each process in group creation, FIG. 6 is a flowchart showing group key creation, and FIG. FIG. 8 is a flowchart showing the decryption process by the receiving side terminal, FIG. 8 is a flowchart showing the decryption process by the receiving side terminal, and FIG. 9 shows that each terminal device installs a security program from the server. FIG. 10 is a conceptual diagram showing a form in the case where the security program is provided in an ASP type.

(overall structure)
As shown in FIG. 1, the information security system according to the present invention is a system configured to transmit and receive a predetermined file between a plurality of terminal devices 10, 20, and 30, and the confidentiality and anonymity of the file are improved. The purpose is to secure.
In this information security system, in order to send and receive files, a “group” in which a plurality of terminal devices can participate is created, and terminal devices not registered in this “group” are included in the network of the information security system. Cannot participate. The file is transmitted and received in the created intra-group network. At this time, it is possible to ensure the anonymity of the sender user and the confidentiality of the file transmitted by the sender user.

  In addition, as a plurality of terminal devices in the present embodiment, a terminal device that transmits the above-mentioned file is a “transmitting terminal”, a terminal device that is designated as a receiver of the file is a “receiving terminal”, and a file receiver A terminal device that is not designated as “non-receiving terminal” is defined. The features and functions of this system will be described in detail below.

(Configuration of terminal device)
FIG. 2 is a block diagram showing a hardware configuration of each terminal device 10, 20, and 30. As shown in FIG.
The transmission side terminal 10 is a CPU 11 that controls the whole transmission side terminal 10 and performs various arithmetic processes, a RAM 12 that temporarily expands and stores various data when writing various data, an operating system, application software, various data, and the like Storing unit 13, an input unit 14 such as a mouse or keyboard, a display unit 15 such as a display, a communication unit 16 connectable to an electric communication line such as the Internet or an intranet, and an output capable of outputting various data to a printer or the like And an input / output port 18 which is an input / output unit for various data.

The basic configuration of the receiving terminal 20 and the non-receiving terminal 30 is the same as that of the transmitting terminal 10 described above. That is, as shown in FIGS. 3A and 3B, the CPU 21, the RAM 22, the storage unit 23, the input unit 24, the display unit 25, the communication unit 26, the output unit 27, and the input / output port 28 are configured. .
Computer programs are installed in the storage units of the transmission side terminal 10, the reception side terminal 20, and the non-reception side terminal 30.

(Program overview)
FIG. 4 is a flowchart showing a form of data transmission / reception in the transmission side terminal 10, the reception side terminal 20, the non-reception side terminal 30, and the non-reception side terminal 40.
The non-receiving side terminal 40 is a terminal device having the same configuration as the non-receiving side terminal 30.
First, a group public key created at the time of group creation is shared with a group creator in advance (S101). At this time, data transmission by unicast is performed from the group creator. All of the terminal devices specified in the group need to perform group public key sharing, thereby establishing the group.

  In addition, the transmission side terminal 10 performs the transmission process of the personal public key sharing (S102). This is the transmission side terminal 10 periodically transmitting to all the terminal devices of the reception side terminal 20, the non-reception side terminal 30, and the non-reception side terminal 40. That is, the personal public key data is transmitted to the intra-group network by broadcasting. This personal public key data is formed with the same data structure as the real data that the transmitting terminal 10 wishes to transmit to the receiving terminal 20. That is, it also functions as dummy data. The transmission interval of the personal public key data can be freely set in advance. Although shortening the transmission interval is preferable in terms of security, it is desirable to set it to a level that does not cause congestion on the intra-group network.

The transmission side terminal 10 creates data for transmission to be transmitted to the reception side terminal 20 (S103).
The transmission data created here is double-encrypted (S104) (S105). Details of the encryption α and encryption β will be described later.
The transmission data encrypted by the encryption α and the encryption β is transmitted by randomly determining any one of the reception side terminal 20, the non-reception side terminal 30 and the non-reception side terminal 40 in the group (S106). .

In the present embodiment, that is, in the example of FIG. 4, it is assumed that the non-reception side terminal 30, the reception side terminal 20, and the non-reception side terminal 40 are transmitted in this order.
First, the non-reception side terminal 30 receives the transmission data transmitted from the transmission side terminal 10 (S107), and decrypts the received transmission data (S108) (S109). Details of the decoding β and the decoding α will be described later.
The non-reception side terminal 30 determines whether or not the real data in the transmission data can be acquired as a result of decoding the received transmission data (S110). Here, as long as data can be acquired, the non-reception-side terminal 30 is not a reception partner designated by the transmission-side terminal 10 and therefore cannot be decrypted. For this reason, data cannot be acquired. When it is determined that the data acquisition is impossible due to the failure in decryption, the non-reception-side terminal 30 transmits the data for transmission received from the transmission-side terminal 10 to other data such as the reception-side terminal 20 and the non-reception-side terminal 40 A terminal is randomly determined and transmitted (S111).

Next, it is assumed that the terminal determined at random is the receiving terminal 20.
The reception side terminal 20 receives the transmission data transmitted from the non-reception side terminal 30 via the transmission side terminal 10 (S112), and decrypts the received transmission data (S113) (S114). As a result of decoding the transmission data received here, it is determined whether or not the real data in the transmission data can be acquired (S115).
Since the receiving side terminal 20 is a real receiving party designated by the transmitting side terminal 10, the receiving side terminal 20 acquires real data in order to succeed in decoding (S116). In the unlikely event that acquisition fails, the transmission data is discarded.

When the real data is acquired, the reception side terminal 20 transmits the reception data indicating that the real data acquisition is successful to the transmission side terminal 10 (S117).
The transmission side terminal 10 receives the reception data transmitted from the reception side terminal 20 (S118), and confirms that acquisition of real data has succeeded (S119). Then, transmission / reception is completed (S120).

  Note that the receiving terminal 20 continues processing thereafter. That is, after transmitting the reception data to the transmission side terminal 10, the transmission data is double-encrypted (S121) (S122), and the transmission destination is randomly determined and transmitted from other terminals in the group ( S123). Here, assuming that the data is transmitted to the non-reception side terminal 40, the transmission data transmitted from the reception side terminal 20 is received (S124), and the received transmission data is decrypted (S125) (S126). . As a result of decoding the transmission data received here, it is determined whether or not the real data in the transmission data can be acquired (S127). Of course, since it is the non-reception side terminal 40, real data cannot be obtained, so the transmission destination of the received transmission data is determined at random from other terminals and transmitted (S128).

  That is, the sender is concealed in a state where the personal public key data is broadcast on the intra-group network. Then, even after the transmission data randomly transmitted from the transmission side terminal 10 reaches the original receiver and the real data is acquired, each terminal device continues to perform the random transmission process. For this reason, it is very difficult to determine from the outside when the data is transmitted from which terminal. Therefore, it contributes to the construction of an extremely advanced security system.

(Loop avoidance)
In the above-described processing, the transmission data transmission processing becomes an infinite loop, which may cause congestion on the network. For this, the number of times of random transmission may be set.
For example, after the receiving terminal 20 acquires real data, random transmission is continued up to 10 times. Random transmission may be continued up to 100 times, or a predetermined range may be set such as 10 to 50 times.

(Grouping process)
Next, details of each process will be described.
As shown in FIG. 5, the grouping process is formed by a group parent and group children (plural). The group parent creates a group (S201). This group creates a group to which only the parent himself belongs (S202).
Here, a user list is created (S203), and only oneself is registered in the user list at this time.

The group child (2) creates the public key [2] and the secret key <2> (S204), and periodically transmits the personal public key [2] by broadcast (S205).
The group parent obtains the personal public key [2] transmitted from the group child (2) (S206). Further, it is selected whether to add a group child (S207).
Here, when the addition of the group child is selected, the user is added to the list (S208). On the other hand, if add is not selected, the data is discarded.
Note that group key sharing (S209) is performed using the acquired personal public key [2] of the group child. As a result, a shared group key is shared.

  The group parent periodically repeats the above-described processing (S205 to 208) to check whether a group child exists with the group child added to the list. If there is no response from the group child for a predetermined time, it is deleted from the user list (S210).

(Group key sharing process)
The group key sharing process is a process for creating a shared key to be used for a group. As shown in FIG. 6, after obtaining the personal public key [2] transmitted from the group child (2), the group parent creates a group public key G and a private key <G> for the group (S301). Then, the secret key <G> is added to the transmission data G (S302). Then, after creating the shared key (g) (S303), the transmission data is encrypted with the shared key (g) (S304). Subsequently, the shared key (g) is encrypted (encrypted γ) with the personal public key [2] (S305), and these data are concatenated (S306). Then, the encrypted concatenated data is transmitted to the group child (1) and the group child (2) (S307).

When the group child (1) receives the concatenated data (S308), decoding is attempted. However, since the personal public key [2] necessary for decryption of the encryption α is not owned, it cannot be decrypted (S309), and the data is discarded (S310).
On the other hand, when the group child (2) receives the concatenated data (S311), it tries decoding (decoding γ). Since the group child (2) possesses the personal public key [2], it can be decrypted. That is, after the concatenated data is divided (S312), the presence / absence of the personal public key [2] is determined (S313). If there is the personal public key [2], this is decrypted with the secret key <2> and the common key (2). g) is extracted (S314). Subsequently, decryption is performed with the common key (g), and data for transmission is extracted (S315). Further, the group public key G and the secret key <G> are disassembled (S316), and the group public key G and the secret key <G> are stored (S317).

(Encryption processing)
The encryption process is a two-stage process of encryption α and encryption β. First, as described above, the group parent creates a group public key G and a secret key <G> for the group (S401), and transmits the created group public key G to the group child (1) that is the sender. (S402).
The group child (1) obtains the group public key G (S403). Also, the group child (2) who is the data receiver for transmission creates the public key [2] and the secret key <2> (S404), and transmits the created public key [2] to the group child (1). (S405). The group child (1) obtains the public key [2] (S406).

Next, transmission data is prepared (S407). Here, a hash function is used for data verification for real data. Further, random numbers are used for the dummy data.
When the transmission data is ready, as a process of encryption α, the group child (1) as the sender creates a common key (1) (S408) and uses the common key (1) to transmit the transmission data. Is encrypted (S409). Subsequently, the created common key (1) is encrypted with the personal public key [2] obtained from the group child (2) designated as the recipient (S410). These encrypted data are concatenated to form concatenated data (S411). The data structure of the concatenated data includes a personal public key [2], an encrypted common key (1 ′), and encrypted transmission data.

  Further, the encryption β processing is as follows. First, a common key (g) is created (S412), and the concatenated data is encrypted using the created common key (g) (S413). Subsequently, the common key (g) is encrypted with the group public key G (S414). These encrypted data are concatenated to form concatenated data (S415). The data structure of the concatenated data includes a group public key G, an encrypted common key (g ′) and encrypted transmission data.

  Next, the group child (1) as the sender randomly transmits the encrypted concatenated data to the users in the group (S416). Here, when a group parent not designated as a recipient has received, after receiving the concatenated data (S417), since the group public key G is owned, decryption β is possible (S418), Since the personal public key [2] is not owned, decryption α is impossible (S419), and the concatenated data is discarded (S420).

(Decryption process)
On the other hand, as shown in FIG. 8, since the group child (2) is a valid recipient, it can be decrypted. In this decoding process, when the concatenated data transmitted from the group child (1) is received (S501), the concatenated data is divided (S502). First, in order to perform the decryption β, it is determined whether or not the group public key G exists (S503). Since the group public key G is owned, the common key (g) is extracted using the secret key [G] (S504). Further, decryption is performed with the common key (g), and data is extracted (S505). At this time, it is not possible to distinguish between real data and dummy data.

  Subsequently, the process of decoding α is performed. This divides the data extracted by the decryption β (S506), and determines whether or not the personal public key [2] exists (S507). Since the group child (2) owns the personal public key [2], the group child (2) decrypts it with the secret key <2> and extracts the common key (1) (S508). Further, decryption is performed using this common key (1), and data is extracted (S509). The extracted data is divided (S510), and the hash value is compared with real data or dummy data (S511). If the hash values are different and dummy data, the dummy data is discarded (S512). On the other hand, the data with the matched hash value is extracted as real data (S513).

  That is, the encryption processing of the present embodiment is a format in which the hybrid encryption method is multiplexed, and the confidentiality is enhanced.

(Client / server type)
FIG. 9 shows a form in which the above-described security program is downloaded from the server and used by each terminal device.
Normally, in order to operate the above-described security program, it is installed in the storage unit of each terminal device. In the form of FIG. 9, this security program is installed from the server 40 to each terminal device. It is a type. Each terminal device is installed in the terminal device by connecting to the server via the Internet or an intranet.
In this way, even if the security program is not installed in the terminal device used by the user, the operation becomes possible, so that it can be used without selecting a place. For this reason, versatility increases.

(ASP type)
As shown in FIG. 10, the server may be provided by an ASP (Application Service Provider) operator.
In other words, if each terminal device has an Internet usage environment and web browser software, the security program provided by the server 50 can be used.

With such a configuration, even if the security program is not installed in the terminal device used by the user, it can operate. For this reason, it can be used without selecting a place, and versatility is enhanced. In addition, for example, considering system use in the company, system management becomes easy. In addition, as a usage form, a method of providing a security program by a rental system or the like can be considered.
Furthermore, when used as an ASP type, it can also be used as a trial before implementing security programs or as a test operation.

It is the conceptual diagram which showed typically the flow of the data between the terminal devices grouped. It is the block diagram which showed the hardware constitutions of the transmission side terminal. It is the block diagram which showed the hardware constitutions of the consultation side terminal and the non-receiving side terminal. It is the flowchart which showed the data transmission between each terminal device. It is the flowchart which showed each process in group creation. It is the flowchart which showed creation of the group key. It is the flowchart which showed the encryption process by the transmission side terminal. It is the flowchart which showed the decoding process by the receiving side terminal. It is the conceptual diagram which showed the form which each terminal device installs and uses a security program from a server. It is the conceptual diagram which showed the form in the case of providing a security program by ASP type.

Explanation of symbols

10 Sending terminal (terminal equipment)
11, 21, 31 CPU
12, 22, 32 RAM
13, 23, 33 Storage unit 14, 15, 34 Input unit 15, 25, 35 Display unit 16, 26, 36 Communication unit 17, 27, 37 Output unit 18, 28, 38 Input / output port 20 Receiving side terminal (terminal device) )
30 Non-receiving terminal (terminal device)
40 server 50 ASP server

Claims (11)

A security program that is installed in a plurality of terminal devices that participate in a group created in advance according to a predetermined arrangement, and that only the terminal device designated as a receiver of real data can receive the real data,
The program is
A group public key transmission procedure for transmitting a group public key that can be acquired by a terminal device authenticated as a group user;
It is shared as a personal public key between the receiving side terminal designated as the receiver of the real data and the transmitting side terminal transmitting the real data, and is also dummy by broadcast transmission to other terminal devices in the group. A dummy packet transmission procedure functioning as
A first encryption procedure for encrypting the transmission data created from the dummy data having the same data structure as the real data and the real data;
A second encryption procedure for further encrypting the transmission data encrypted by the first encryption procedure;
The transmission data encrypted by the second encryption procedure can be randomly selected from a plurality of terminal devices in the group and transmitted, and a random transmission procedure can be executed.
A decoding determination procedure for determining whether or not a predetermined terminal device that has received the transmission data transmitted by the random transmission procedure executed by another terminal device related to the group can decode the transmission data;
When the real data can be extracted from the transmission data received by the decryption determination procedure, a dummy packet random transmission procedure for randomly transmitting the transmission data encrypted from the terminal device to another terminal device; ,
A security program that causes a computer to execute. A security program that is installed in a plurality of terminal devices that participate in a group created in advance according to a predetermined arrangement, and that only the terminal device designated as a receiver of real data can receive the real data,
The program is
A group public key transmission procedure for transmitting a group public key that can be acquired by a terminal device authenticated as a group user;
It is shared as a personal public key between the receiving side terminal designated as the receiver of the real data and the transmitting side terminal transmitting the real data, and is also dummy by broadcast transmission to other terminal devices in the group. A dummy packet transmission procedure functioning as
A first encryption procedure for encrypting the transmission data created from the dummy data having the same data structure as the real data and the real data;
A second encryption procedure for further encrypting the transmission data encrypted by the first encryption procedure;
The transmission data encrypted by the second encryption procedure can be randomly selected from a plurality of terminal devices in the group and transmitted, and a random transmission procedure can be executed.
A decoding determination procedure for determining whether or not a predetermined terminal device that has received the transmission data transmitted by the random transmission procedure executed by another terminal device related to the group can decode the transmission data;
When the real data cannot be extracted from the transmission data received by the decoding determination procedure, a dummy packet random transmission procedure for randomly transmitting the transmission data from the terminal device to another terminal device;
A security program that causes a computer to execute.   The security program according to claim 1, wherein the dummy packet is formed with the same data structure as that of real data. Wherein the first encryption procedure, a common key generation procedure for creating a common key, a common key encryption procedure for encrypting the transmission data with the common key,
A public key encryption procedure for encrypting the common key with a personal public key created by the receiving terminal;
Concatenated data creation procedure for concatenating the personal public key, the encrypted common key and the encrypted transmission data as one data,
The security program according to any one of claims 1 to 3, further comprising: The second encryption procedure includes a second common key creation procedure in which the second encryption procedure creates a second common key;
A concatenated data encryption procedure for encrypting concatenated data using the second common key created in the second common key creation procedure;
A group public key encryption procedure for encrypting the encrypted second common key with the group public key G;
A second concatenated data creation procedure for concatenating the group public key G, the encrypted second common key, and the encrypted transmission data as one data;
The security program according to claim 4, further comprising:   A server characterized in that the security program according to claim 1 can be used by being connected to each of the terminal devices via the Internet or an intranet.   A server characterized in that the security program according to claim 2 can be used by being connected to each terminal device via the Internet or an intranet.   A server characterized in that the security program according to claim 3 can be used by being connected to each terminal device via the Internet or an intranet.   A server characterized in that the security program according to claim 4 can be used by being connected to each terminal device via the Internet or an intranet.   A server characterized in that the security program according to claim 5 can be used by being connected to each terminal device via the Internet or an intranet.   The server according to claim 6, wherein the server is an application service provider.

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