JP6786455B2 - Communication system, public key cryptosystem and its method - Google Patents

Description

Embodiments of the present invention relate to communication systems, public key cryptosystems and methods thereof.

A common key encryption method is known in which data is encrypted using a common key and the encrypted data is decrypted. Further, a public key cryptosystem is known in which data is encrypted using a public key and the data encrypted using a private key is decrypted. Further, in an encrypted communication system, a registration / authentication method using a server for managing and distributing an encryption key is known.

Japanese Unexamined Patent Publication No. H11-96658 Japanese Patent No. 3628250

In a group of n communication devices, a method is known in which communication devices communicate encrypted data using a common key to conceal information sent from a source to a receiver. In this group, 2 ^(n-1) -1 types of common keys are required to send encrypted data from one communication device to the other 1 to (n-1) communication devices. Will be done. Therefore, in such a group, the management of the common key becomes very complicated. Further, the encrypted communication method by the registration / authentication method using a server shown as the background technology cannot be applied to a communication system including only a communication device and not a server or a base station.

Embodiments of the present invention are made to solve the above-mentioned problems, and data to a communication partner is encrypted and transmitted with a small number of types of encryption keys without a server or a base station, and data to a communication partner other than the communication partner. It is an object of the present invention to provide a communication system, a public key cryptosystem, and a method thereof that can reliably conceal the data.

Embodiments of the present invention are made to solve the above-mentioned problems, and data to a communication partner is encrypted and transmitted with a small number of types of encryption keys without a server or a base station, and data to a communication partner other than the communication partner. It is an object of the present invention to provide a communication system, a public key cryptosystem, and a method thereof that can reliably conceal the data.

In order to solve the above-described problems, the communication system according to the embodiment of the present invention is a communication system including a plurality of communication devices that perform data communication with each other, and each of the plurality of communication devices has its own communication device. Is set with a unique public key used for encrypting data and a unique private key used for decrypting data encrypted using the unique public key, and each of the plurality of communication devices is set. A storage means for storing all the public keys set in the communication device and all the private keys set in the other communication device, and one of the stored public keys as a data communication partner. An encryption means for encrypting transmission data to be transmitted to obtain encrypted data by using all of the public keys set in the communication device other than the above communication device, and the obtained encrypted data. Of the stored private key, the transmitting means for transmitting the data to all of the other communication devices, the receiving means for receiving the encrypted data transmitted from any of the plurality of communication devices, and the data. It has a decryption means for decrypting the transmission data from the received encrypted data by using all of the private keys set in the communication device other than one or more communication devices of the communication partner. ..

It is a figure which shows the structure of the communication system which concerns on embodiment of this invention. It is a figure which shows the contents of the public key / private key table which one of the n communication devices included in the communication system shown in FIG. 1 stores. It is a figure which shows the packet used for the transmission of the encrypted data. It is a figure which shows the structure of the communication apparatus shown in FIG. It is a flowchart which shows the encryption process (S10) by the communication device of the communication system shown in FIGS. 1 and 4. It is a flowchart which shows the decoding process (S20) by the communication device of the communication system shown in FIGS. 1 and 4.

[Method of encryption and decryption in communication system 1]
Hereinafter, embodiments will be described in detail with reference to the drawings. First, an encryption and decryption method that is a prerequisite for processing in the communication system 1 according to the embodiment of the present invention will be described. FIG. 1 is a diagram showing a configuration of a communication system 1 according to an embodiment of the present invention. Note that FIG. 1 shows the case where n = 8. FIG. 2 is one of n communication devices 2-1 to 2-n (communication devices) included in the communication system 1 shown in FIG. 1 (communication device 2-i; i is any one of 1 to n). It is a figure which shows the contents of the public key / private key table which is stored in. FIG. 3 is a diagram showing packets used for transmitting encrypted data. Hereinafter, when any of a plurality of components such as "communication device 2-1 to 2-n" that may be present in the communication system 1 such as the communication device 2-1 to 2-n is shown without being specified, it is simply shown. It may be abbreviated as "communication device 2" or the like. Further, hereinafter, "encrypted data" is also described as "encrypted data".

As shown in FIG. 1, the communication system 1 includes n communication devices 2-1 to 2-n capable of communicating with each other via a wired communication circuit and / or a wireless communication circuit, and an encryption key. Does not include a device that manages and distributes to each of the communication devices 2. Each of the communication devices 2 transmits the encrypted data Me in which the data Mo to be encrypted is encrypted by the public key encryption method with the other communication device 2 of the communication partner, and the transmitted encryption is performed. The encrypted data Me is received, decrypted into the encrypted data Mo, and communicated.

Identification numbers ID # 1 to ID # n are uniquely set for each of the communication devices 2-1 to 2-n. Further, the public keys Pu1 to Pun and the private keys Pr1 to Prn are uniquely set in each of the communication devices 2-1 to 2-n. In each figure, the notation of communication devices 2-1, 2-2, 2-3, ..., I-1, i, i + 1, ..., N-1, n in each figure is mathematical. It does not mean that i is 5 or more and n-2 or less according to the custom in.

The communication device 2-i stores the public key / private key table shown in FIG. In the public key / private key table, IDs # 1 to ID # n of each of the communication devices 2-1 to 2-n and the public keys set to each of the communication devices 2-1 to 2-n included in the communication system 1 Of all the keys Pu1 to Pun and the private keys Pr1 to Prn set in the communication devices 2-1 to 2-n respectively, the private keys Pr1 to Pr other than the private key Pri set in the communication device 2-i itself. (I-1), Pr (i + 1) to Prn are stored in association with IDs # 1 to ID # n of the communication device 2.

As shown by the downward arrow in FIG. 2, the public keys Pu1 to Pun are the communication devices 2-with the largest ID values from the public keys Pu1 set in the communication device 2-1 with the smallest ID values. It is used for encryption in the order of the public key Pun set to n. Further, the private keys Pr1 to Pr (i-1) and Pr (i + 1) to Prn are open to the public in which the ID value is set to the maximum communication device 2-n as shown by the upward arrow in FIG. It is used for decryption in the order from the key Prn to the public key Pr1 set in the communication device 2 having the smallest ID value.

As shown in FIG. 3, at least the identifier IDe of the communication device 2 other than the communication partner is stored in the header of the packet used for transmitting the encrypted data. Note that IDe indicates a set of IDs of communication devices 2 other than the communication partner. In addition, the payload part of this packet stores the encrypted data body, and if necessary, a footer containing an error correction code and other data is added to the last part of the packet.

In the public / private key table of the communication device 2-i, as shown in FIG. 2, all the public keys Pu1 to Pun set in the communication device 2 and other than the communication device 2-i are set. All private keys Pr1 to Pr (i-1) and Pr (i + 1) to Prn are stored. That is, in the communication device 2-i, the private key Pui set in the communication device 2-i itself is not stored.

[Specific methods of encryption and decryption]
Hereinafter, in order to facilitate understanding, in the communication system 1, the communication device 2-1 of the transmission source communicates with the communication devices 2-2, 2-5, 2-n as communication partners, and these communication devices In addition to 2, a case where the communication content is to be kept secret will be described as a specific example. In this case, the communication device 2-1 is a communication device 2-3, 2-4, 2-6 to 2- (n-1) other than the communication device 2-2, 2-5, 2-n of the communication partner. ) And the public key Pu1 set in the communication device 2-1 itself, the data Mo to be encrypted is encrypted as shown in the following equation 2 to obtain the encrypted data Me.

Me = Mo ・ Pu1, Pu3 ・ Pu4 ・ Pu6 ... Pu (n-1) (Equation 2)

As described above, the communication device 2-i does not store the private key Pri set in itself. That is, each of the communication devices 2-3, 2-4, 2-6 to 2- (n-1) in which the communication device 2-1 tries to conceal the contents of the data Mo to be encrypted is the private key Pr3, Pr4. Each of Pr6 to Pr (n-1) is not memorized. Therefore, each of the communication devices 2-3, 2-4, 2-6 to 2- (n-1) cannot decrypt the encryption target data Mo shown in the above equation 2.

On the other hand, the communication device 2-2, 2-5, 2-n stores the private keys Pr1, Pr3, Pr4, Pr6 to Pr (n-1). Therefore, the communication device 2-2, 2-5, 2-n transfers the encrypted data Me shown in the above formula 2 to the private keys Pr3, Pr4, Pr6 to Pr (n-) as shown in the following formula 3. It can be decrypted into the data Mo to be encrypted by using 1). Needless to say, it is not necessary for the transmitting communication device 2-1 to decrypt the encrypted data Me shown in the above equation 2.

Me ・ Pr (n-1) ・ ・ ・ ・ ・ Pr6 ・ Pr4 ・ Pr3
= Mo, Pu1, Pu3, Pu4, Pu6 ... (Pu (n-1), Pr (n-1)) ... Pr6, Pr4, Pr3, Pr1
= Mo, Pu1, Pu3, Pu4, Pu6 ... (Pu (n-2), Pr (n-2)) ... Pr6, Pr4, Pr3, Pr1
・
・
・
= Mo, Pu1, Pu3, Pu4, (Pu6, Pr6), Pr4, Pr3, Pr1
= Mo, Pu1, Pu3, (Pu4, Pr4), Pr3, Pr1
= Mo ・ Pu1 ・ (Pu3 ・ Pr3) ・ Pr1
= Mo ・ (Pu1 ・ Pr1)
= Mo (Equation 3)

As described above, the communication device 2-1 includes the public key Pu1 set in the communication device 2-1 itself and the communication device 2-3, 2-4, 2-6 to which the contents of the encrypted data are kept secret. The encryption target data Mo is encrypted using all of the public keys Pu3, Pu4, Pu6 ... Pu (n-1) set in 2- (n-1) to obtain the encrypted data Me. When the communication device 2-1 broadcasts a packet (FIG. 3) containing such encrypted data Me to all of the other communication devices 2-2-2-n, the other communication device 2- All of 2-2-n receive the encrypted data Me from the communication device 2-1.

However, as described with reference to the above equation 3, only the communication device 2-2, 2-5, 2-n of the communication partner can decrypt the encrypted data Mo from the received encrypted data Me. As described above, the encrypted data Me that can be decrypted is transmitted from the communication device 2-1 only in the communication device 2-2, 2-5, 2-n of the communication partner. On the other hand, in the communication devices 2-3, 2-4, 2-6 to 2- (n-1) other than the communication partner, the encrypted data Me transmitted by the communication device 2-1 is not decrypted and is encrypted. The contents of the target data Mo are kept secret.

However, in the communication device 2-2, 2-5, 2-n of the communication partner of the communication device 2-1 which of the public keys set in the communication device 2 in the encryption in the communication device 2-1 is used. It is necessary to be notified in what order they were used. The information indicating these is stored in the header of the packet as shown in FIG. As shown in FIG. 2, when the order of using the public key and the private key used for encrypting the encrypted data Mo and decrypting the encrypted data Me is predetermined, the encrypted data Me is used. Only the ID of the communication device 2 whose contents are kept secret needs to be stored in the header.

As mentioned above, the communication method by the public key cryptosystem between the specific communication device 2-1 and the communication device 2-2, 2-5, 2-n has been taken as a specific example. Any communication device 2 of the communication system 1 can also be generalized and applied when one or more other arbitrary communication devices 2 are used as communication partners.

[Configuration of communication device 2]
FIG. 4 is a diagram showing the configuration of the communication device 2-i shown in FIG. As shown in FIG. 4, the transmission / reception device 20, the communication processing device 22, and the public key encryption device 24-i connected via the bus 230 are provided.

The transmission / reception device 20 includes a transmission circuit 200 (transmission means) for transmitting data to the antenna or network, and a reception circuit 202 (reception means) for receiving data from the antenna or network. The transmission circuit 200 transmits a packet (FIG. 3) containing the encrypted data Me to another communication device 2 via an antenna or a network. The receiving circuit 202 receives the packet storing the encrypted data Me from another communication device 2 via the antenna or the network, and also receives the encrypted data Mo to be encrypted via the network. To do.

The communication processing device 22 includes an arithmetic circuit 220, a memory 222, a recording device 224, and an input / output device interface (IF) 226 connected via a bus 230, and an input / output device 228 is connected to the output device IF 226. The arithmetic circuit 220 includes peripheral circuits such as a CPU and an interrupt controller, and executes a program loaded into the memory 222 from the reception circuit 202 of the recording device 224 or the transmission / reception device 20. The memory 222 includes a RAM and a ROM, stores a program loaded as described above and executed by the arithmetic circuit 220, and operates as a working memory used when the program is executed.

The recording device 224 writes the encrypted data Mo to be encrypted, the decrypted encrypted data Mo, and other data to and from a non-volatile storage medium such as an HDD, a CD, a DVD, or a flash memory. And read. The input / output device IF226 outputs the data input from the input / output device 228 to other components of the communication device 2 via the bus 230, and is input from the other components of the communication device 2 via the bus 230. The data is output to the input / output device 228.

The input / output device 228 accepts the user's operation, outputs data indicating the accepted user's operation to the input / output device IF226, and displays the data input from the input / output device IF226 to the user. The communication processing device 22 controls the encryption processing, the decryption processing, and the communication processing in the communication processing device 22 by these components.

The public key cryptography device 24-i (public key cryptography device) of the communication device 2-i includes an encryption key memory 240-i (storage means) for storing a public key, a private key (FIG. 2), and other data. , Includes an encryption circuit 242 (encryption means) that encrypts the encryption target data Mo by a public key cryptosystem, and a decryption circuit 244 (decryption means) that decrypts the encryption target data Mo from the encrypted data Me. .. The public key cryptosystem 24-i uses the public key and the private key (FIG. 2) stored in the encryption key memory 240-i by these components, and the encryption target data input from the transmission / reception device 20. Mo is encrypted to be encrypted data Me. Further, the public key encryption device 24-i decrypts the encrypted data Me input from the transmission / reception device 20 into the encryption target data Mo by these components. That is, the public key cryptosystem 24-i realizes the public key cryptosystem by the method described above with reference to FIGS. 1 to 3.

The encryption key memory 240-i, the encryption circuit 242, and the decryption circuit 244 of the public key encryption device 24-i are incorporated in the same semiconductor chip. In addition, the encryption key memory 240-i outputs the stored public key and private key, except that the ID # i of the communication device 2-i shown in FIG. 2 is output to the outside of the public key encryption device 24-i. Inside the public key cryptosystem 24-i, the output is output only to the encryption circuit 242 and the decryption circuit 244.

In addition, public keys Pu1 to Pu (i-1), Pu (i + 1) to Pun, private keys Pr1 to Pr (i-1), Pr (i + 1) to Pr, and a communication device stored in the encryption key memory 240-i. The content of ID # i of 2-i is unique to the communication device 2-i. Further, for confidentiality, other than the ID # i of the communication device 2-i, it must not be read from the encryption key memory 240-i to the outside of the public key encryption device 24-i. That is, the public keys Pu1 to Pun, the private keys Pr1 to Pr (i-1), and Pr (i + 1) to Prn must not be read out of the encryption key memory 240-i. Therefore, these keys are written in hardware in the semiconductor chip at the time of manufacturing the semiconductor chip so that they are not read from the encryption key memory 240-i without destroying the semiconductor chip.

[Operation of communication device 2]
Hereinafter, the overall operation of the communication device 2 will be described. FIG. 5 is a flowchart showing an encryption process (S10) by the communication device 2-i of the communication system 1 shown in FIGS. 1 and 4. FIG. 6 is a flowchart showing a decoding process (S20) by the communication device 2-i of the communication system 1 shown in FIGS. 1 and 4.

[Encryption and transmission]
First, the operation of the communication device 2-i for encrypting the data Mo to be encrypted and transmitting the encrypted data Me obtained as a result of the encryption will be described. A program (not shown) for communication control of the communication device 2-i is loaded in the memory 222 of the communication processing device 22 shown in FIG. 4, and the arithmetic circuit 220 executes the loaded program.

Further, the ID # i of the communication device 2-i is read from the encryption key memory 240-i of the public key encryption device 24-i and stored in the memory 222. Further, when the encryption target data Mo is input from the reception circuit 202 or the recording device 224 of the transmission / reception device 20, the arithmetic circuit 220 stores the input encryption target data Mo in the memory 222.

In step S100 shown in FIG. 5, the user encrypts the input / output device 228 of the communication processing device 22 of the communication device 2-i with the identifier IDd of one or more other communication devices 2 as the communication partner. Perform an operation to specify the target data Mo. The IDd is a set of IDs of the communication device 2 other than the communication device 2-i, which is the communication partner. The input / output device 228 accepts these operations by the user and specifies that the IDd of one or more other communication devices 2 to be communicated with and the communication device 2 of the transmission source and the data Mo to be encrypted are specified. The data to be output is output to the input / output device IF226.

In step S102, the input / output device IF226 notifies the arithmetic circuit 220 of the input of these data by an interrupt, and stores the input data in the memory 222. Further, the arithmetic circuit 220 is stored in the memory, and the communication device 2 other than the communication device 2 as the communication partner, that is, the communication device 2 and the transmission source whose contents of the encrypted data Me should be concealed other than the communication partner. Obtain the IDe of the communication device 2-i. This IDe is obtained as a complement of IDd in the set of IDs of all the communication devices 2 included in the communication system 1. Further, the arithmetic circuit 220 sorts (sorts) the IDe of the communication device 2 of the secret destination and the communication device 2 of the transmission source of the contents of the encrypted data Me so that the smaller value comes first and the larger value comes later. , Output to the encryption circuit 242 of the public key encryption device 24-i.

In step S104, the encryption circuit 242 of the public key cryptographic device 24-i refers to the encryption key memory 240-i, sorts the public key corresponding to the IDe of the communication device 2 input from the communication processing device 22. Pue is read out in the order indicated by the downward arrow in FIG. However, Pue is a set of public keys corresponding to IDE.

In step S110, the encryption circuit 242 determines whether or not the encryption using the public key Pue read in step S104 is completed. When the encryption using all the public keys Pue is completed (S112: Y), the encryption circuit 242 proceeds to the process of S120, and at other times, proceeds to the process of (N) S112.

In step S112, the encryption circuit 242 uses the public key Puj corresponding to the ID of the communication device 2 having the smallest value, which has not yet been used for encryption, among all the public key Pues read in S104. get.

In step S114, the encryption circuit 242 encrypts the data Mo to be encrypted using the public key Puj acquired in the process of S112. In the encryption of the encryption target data Mo, the encryption target data Mo is encrypted, and the encryption target data Mo already encrypted using another public key is acquired in the process of S112. It includes further encryption with the public key Puji.

In step S120, the encryption circuit 242 outputs the encrypted data Me, which has been encrypted, to the communication processing device 22 as described with reference to the above equation 2.

In step S122, the arithmetic circuit 220 of the communication processing device 22 generates the transmission packet shown in FIG. That is, the receiving circuit stores the IDe of the communication device 2 other than the communication partner obtained by the processing of S102 as the data for decoding in the communication device 2 of the communication partner. Further, the arithmetic circuit 220 stores the encrypted data Me output by the encryption circuit 242 in the processing of S120 in the payload portion of the packet, and further adds a footer to the packet as needed.

In step S124, the communication processing device 22 outputs the packet generated in the processing of S122 to the transmission circuit 200 of the transmission / reception device 20, and causes all the communication devices 2 included in the communication system 1 to broadcast transmission.

[Receive and decrypt]
Next, the operation of the communication device 2-i when the packet for transmission shown in FIG. 3 is received from the other communication device 2 will be described. In step S200, the reception circuit 202 of the transmission / reception device 20 of the communication device 2-i receives the transmission packet broadcast-transmitted from the other communication device 2 and outputs it to the communication processing device 22.

In step S202, the communication processing device 22 acquires the IDe of the communication device 2 other than the communication partner from the header of the received packet.

In step S204, the communication processing device 22 determines whether or not the ID # i of the communication device 2-i is included in the IDe of the communication device 2 other than the communication partner acquired in the process of S202. That is, the communication processing device 22 determines whether or not the communication device 2-i is the transmission destination of the packet.

The communication processing device 22 ends the processing when the communication device 2-i is not the transmission destination of the packet (S204: Y), that is, when it is not the communication partner. At other times (same: N), the communication processing device 22 outputs the IDe of the communication device 2 other than the communication partner acquired in the processing of S202 to the decryption circuit 244 of the public key encryption device 24-i. , S206. The IDe of the communication device 2 other than the communication partner acquired in S202 is processed by S102 shown in FIG. 5 in the transmission source communication device 2, so that the smaller value comes first and the larger value comes later. It is sorted so that

In step S206, the decoding circuit 244 reads the IDE of the communication device 2 other than the communication partner input from the communication processing device 22 from the back in the process of S204, and the IDE with a large value comes first and the IDE with a small value comes after. Sort as follows. Further, the decryption circuit 244 refers to the encryption key memory 240-i and displays the private key Pre corresponding to the sorted IDe of the communication device 2 as the corresponding public key as shown by the upward arrow in FIG. Read in the reverse order of Pue. Pre indicates a set of private keys corresponding to IDE.

In S210, the decoding circuit 244 determines whether or not the decoding using all the secret keys Prk included in the secret key Pre in S206 has been completed. When the encryption using all the private keys Prk included in the private key Pre is completed (S210: Y), the decryption circuit 244 proceeds to the process of S220, and at other times (same: N) proceeds to the process of S212. ..

In step S212, the decoding circuit 244 acquires the public key Prk corresponding to the IDE having the largest value, which has not yet been used for decoding, among all the private keys Pre read in S206.

In step S214, the decryption circuit 244 decrypts the encrypted data Me into the encryption target data Mo by using the private key Prk acquired in the process of S212. In order to decrypt the encrypted data Me, the encrypted data Me is decrypted, and the encrypted data Me already decrypted by using another private key Prk is further decrypted by the private key Prk acquired in the process of S212. Includes decryption.

In step S216, the decryption circuit 244 outputs the encryption target data Mo obtained by the decryption to the communication processing device 22. The communication processing device 22 displays the encryption target data Mo input from the decryption circuit 244 on the input / output device 228, and further stores it in the storage medium of the recording device 224.

[Technical effect]
According to the communication device 2 described above, the number of public keys to be stored in each communication device 2 is n-1, and the number of private keys is n. Therefore, the number of encryption and decryption keys stored in each of the communication devices 2 may be 2n-1, and the number of keys for the entire communication system 1 may be 2n. Therefore, it is easier to manage the encryption and decryption keys in the communication system 1 as compared with the case where the communication devices 2 transmit the encrypted data using the common key and decrypt the data using the private key. ..

[Modification example]
Note that only the IDd of the communication device 2 of the communication partner may be stored in the header of the packet shown in FIG. In this case, for decryption, the secret keys associated with the IDes of all the communication devices 2 excluding the IDd of the communication device 2 stored in the header are in the order shown in FIG. Used for decoding. Further, in the header of this packet, the identification number of the communication device 2 of the communication partner may be stored in the order of the smallest value to the largest value. Further, other data required for realizing the communication method used in the communication system 1 may be appropriately stored in the header of this packet.

Further, as described above, the operation of the communication device 2 when the public keys stored in the encryption key memory 240 as shown in FIG. 2 are read out in the order indicated by the downward arrow and the encryption is sequentially performed. As described above, the order of reading the public key may be another predetermined order. Further, as shown in the above equation 3, the reading order of the private key may be the reverse order of reading the public key corresponding to the private key, and may not be the order described with reference to FIG. .. Further, the communication system 1 may be an ad hoc communication system.

Although embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 Communication system 2 Communication device 20 Transmission / reception device 200 Transmission circuit 202 Reception circuit 22 Communication control device 220 Calculation circuit 222 Memory 224 Recording device 226 Input / output device IF
228 I / O device 230 Bus 24 Public key cryptographic device 240 Cryptographic key memory 242 Cryptographic circuit 244 Decryption circuit

Claims (11)

It is a communication system including a plurality of communication devices that perform data communication with each other, and each of the plurality of communication devices is encrypted using a unique public key used for data encryption and the unique public key. A unique private key used to decrypt the converted data is set, and
Each of the plurality of communication devices
A storage means for storing all the public keys set in the communication device and all the private keys set in the other communication device.
Among the stored public keys, all of the public keys set in the communication device other than one or more communication devices of the data communication partner are used to encrypt and encrypt the transmission data to be transmitted. Cryptographic means to obtain encrypted data,
A transmission means for transmitting the obtained encrypted data to all of the other communication devices, and
A receiving means for receiving the encrypted data transmitted from any of the plurality of communication devices, and
Among the stored private keys, the transmission from the received encrypted data using all of the private keys set in the communication device other than one or more communication devices of the data communication partner. Decryption means for decrypting data and
Communication system with. The communication system according to claim 1, wherein the encryption means performs the encryption by using the public keys used for the encryption among the stored public keys in a certain order. The decryption means uses the private key corresponding to the public key used for the encryption among the stored private keys in the order opposite to the order in which the corresponding public key is used. The communication system according to claim 1 or 2, wherein the decoding is performed. The transmitting means transmits the encrypted data with data indicating the communication device other than the one or more communication devices of the other party of the data communication.
Based on the data attached to the encrypted data, the decryption means uses all of the private keys set in the communication device other than one or more communication devices of the data communication partner to transmit the data. The communication system according to any one of claims 1 to 3, wherein the data is decrypted. The storage means stores all the public keys set in the communication device and all the private keys set in the other communication device in a non-readable manner outside the communication device. 4. The communication system according to any one of 4. Each of a plurality of public key cryptosystems including an encryption means and a decryption means,
Each of the plurality of public key cryptosystems
A storage means for storing all the public keys uniquely set for the plurality of public key cryptographic devices and all the private keys uniquely set for the other public key cryptographic devices.
Data to be encrypted using all of the public keys set in the public key cryptosystem other than the public key cryptosystem that decrypts the encrypted data among the stored public keys. Cryptographic means to obtain encrypted data by encrypting
A distribution means for distributing the obtained encrypted data to all of the other public key cryptosystems, and
A receiving means for receiving the encrypted data delivered from any of the other public key cryptographic devices, and
Among the stored private keys, the encryption received by using all of the private keys set in the public key encryption device other than the public key encryption device that decrypts the encrypted data. Decryption means to decrypt data and
Public key cryptosystem with. Each of multiple public key cryptosystems
A storage means for storing all of the public keys uniquely set for the plurality of public key cryptosystems, and
Data to be encrypted using all of the public keys set in the public key cryptographic device other than the public key cryptographic device that decrypts the encrypted data among the stored public keys. Cryptographic means to obtain encrypted data by encrypting
Public key cryptosystem with. Each of the plurality of public key cryptosystems has one or more other public key cryptosystems as communication partners.
In each of the plurality of public key cryptosystems
The storage means further stores all of the private keys uniquely set in the other public key cryptosystem.
Each of the plurality of public key cryptosystems
A distribution means for distributing the obtained encrypted data to all of the other public key cryptosystems, and
A receiving means for receiving the encrypted data distributed from any of the plurality of public key cryptographic devices, and
From the encrypted data delivered using all of the private keys set in the public key encryption device other than the public key encryption device used as the communication partner among the stored private keys. Decryption means that decrypts the data to be encrypted,
The public key cryptosystem according to claim 7, further comprising. It is a public key cryptosystem in each of a plurality of public key cryptosystems including an encryption means and a decryption means, respectively.
Each of the plurality of public key cryptosystems
All the public keys uniquely set for the plurality of public key cryptographic devices and all the private keys uniquely set for the other public key cryptographic devices are stored.
Data to be encrypted using all of the public keys set in the public key cryptosystem other than the public key cryptosystem that decrypts the encrypted data among the stored public keys. To obtain encrypted data by encrypting
The obtained encrypted data is distributed to all of the other public key cryptographic devices.
Upon receiving the encrypted data delivered from any of the other public key cryptographic devices,
Among the stored private keys, the encryption received by using all of the private keys set in the public key encryption device other than the public key encryption device that decrypts the encrypted data. A public key cryptosystem that decrypts data. This is a public key cryptosystem for each of multiple public key cryptosystems.
All of the public keys uniquely set for the plurality of public key cryptosystems are stored.
Data to be encrypted using all of the public keys set in the public key cryptosystem other than the public key cryptosystem that decrypts the encrypted data among the stored public keys. Public key cryptography to obtain encrypted data by encrypting. Each of the plurality of public key cryptosystems has one or more other public key cryptosystems as communication partners.
In each of the plurality of public key cryptosystems
Further memorize all of the private keys uniquely set in the other public key cryptosystem,
The obtained encrypted data is distributed to all of the other public key cryptographic devices.
Upon receiving the encrypted data delivered from any of the plurality of public key cryptographic devices,
From the encrypted data delivered using all of the private keys set in the public key cryptographic device other than the public key cryptographic device used as the communication partner among the stored private keys. The public key cryptography method according to claim 10, wherein the data to be encrypted is decrypted.

Images