Electronic voting system, electronic voting method, and electronic voting program

Abstract

The present invention contributes to verifying the details of voting in an anonymous vote. This electronic voting system for transmitting / receiving to / from electronic voting terminals with which voters perform electronic voting comprises: a voting right management device for issuing voting IDs to the voters on the basis of a list of voters; a voting processing device for performing personal identification of the voters by receiving, from the electronic voting terminals, the voting IDs and electronic voting information in which voting details are assigned with electronic signatures and by checking the voting IDs, the voting details, and the electronic signatures, and for recording, as voting data, data in which the voting IDs and the electronic signatures are removed from the electronic voting information; and at least three secret sharing server devices for recording the voting IDs, the voting details, and the electronic signatures by performing secret sharing thereof.

Description

[Technical field]

[0001] The present invention relates to an electronic voting system, an electronic voting method, and an electronic voting program. [Background technology]

[0002] In secret ballots such as those used in elections, paper ballots are generally used. The reason for this is that in elections, there is a strict requirement to prevent multiple voting and to guarantee anonymity, and the use of paper ballots ensures this. In order to computerize secret ballots such as those used in elections, or to realize so-called electronic voting, the same prevention of multiple voting and guarantee of anonymity that is achieved by using paper ballots will also be required for electronic voting.

[0003] For example, in a typical election, instead of mailing ballots to voters, a mail item that can be exchanged for a ballot at the polling station is sent, and voters who receive the mail exchange it for a ballot at the polling station and place the ballot in a ballot box. With this system, although the mail item sent contains the address and name, voters can vote without writing their name on the ballot, so anonymity is guaranteed. Also, if mail that can be exchanged for a ballot is sent only to those who are listed on the voter register, and the mail item is collected when the ballot is exchanged, multiple voting can be prevented.

[0004] In electronic voting, it is necessary to implement such prevention of multiple voting and guarantee of anonymity as electronic processing. For example, Patent Document 1 describes mechanisms such as voting tokens and electronic signatures to prevent such multiple voting and guarantee anonymity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-095884 A Summary of the Invention [Problem to be solved by the invention]

[0006] The disclosures of the above-mentioned prior art documents are incorporated herein by reference. The following analysis has been carried out by the present inventors.

[0007] Incidentally, electronic voting requires reliability from a different perspective than traditional voting using paper ballots. This is the verification of the vote contents. For example, if there is a possibility that a fraudulent vote has been cast, the vote contents must be verified after the fact, but since electronic voting deals with electronic data, a different perspective arises from paper voting. With paper ballots, it is not possible to commit fraud such as rewriting the ballot paper in the ballot box from outside, but with electronic voting, reliability must be guaranteed, including the possibility that voting data can be rewritten from outside or that data may be corrupted unexpectedly.

[0008] However, it is difficult to verify the contents of votes from anonymized voting data. For example, it is virtually impossible to verify, using the anonymized voting data, whether the data contains votes from people not included in the voter roll, or whether the same person's votes are included multiple times.

[0009] In view of the above-mentioned problems, an object of the present invention is to provide an electronic voting system, an electronic voting method, and an electronic voting program that contribute to verifying the voting contents in secret ballots. [Means for solving the problem]

[0010] In a first aspect of the present invention, there is provided an electronic voting system in which voters transmit and receive information to and from an electronic voting terminal where they cast their electronic votes, the electronic voting system comprising: a voting rights management device which issues a voting ID to the voter based on a voter list; a voting processing device which receives electronic voting information with an electronic signature attached to the voting ID and voting content from the electronic voting terminal, verifying the identity of the voter by comparing the voting ID and voting content with the electronic signature, and recording the electronic voting information with the voting ID and electronic signature removed as voting data; and at least three secret sharing server devices which secretly share and record the voting ID, voting content, and electronic signature.

[0011] A second aspect of the present invention provides an electronic voting method using an electronic voting system in which a voter transmits and receives information to an electronic voting terminal where the voter casts an electronic vote, the electronic voting system issues a voting ID to the voter based on a voter list, receives electronic voting information from the electronic voting terminal with an electronic signature attached to the voting ID and the voting content, verifies the identity of the voter by comparing the voting ID and the voting content with the electronic signature, records the electronic voting information with the voting ID and the electronic signature removed as voting data, and secretly shares and records the voting ID, the voting content, and the electronic signature.

[0012] The third aspect of the present invention provides an electronic voting program executed by an electronic voting system that transmits and receives data to an electronic voting terminal where a voter performs electronic voting, which executes the following: issuing a voting ID to the voter based on a voter list; receiving electronic voting information with an electronic signature attached to the voting ID and the voting contents from the electronic voting terminal; verifying the identity of the voter by comparing the voting ID and the voting contents with the electronic signature; recording the electronic voting information with the voting ID and the electronic signature removed as voting data; and recording the voting ID, the voting contents, and the electronic signature in a secret sharing manner. This program can be recorded in a computer-readable storage medium. The storage medium can be a non-transient medium such as a semiconductor memory, a hard disk, a magnetic recording medium, or an optical recording medium. The present invention can also be embodied as a computer program product. Effect of the Invention

[0013] According to each aspect of the present invention, it is possible to provide an electronic voting system, an electronic voting method, and an electronic voting program that contribute to verifying the voting contents in secret ballots. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram showing an electronic voting system according to the first embodiment. [Diagram 2] FIG. 2 is a schematic system flow diagram showing the electronic voting method according to the first embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a hardware configuration of an apparatus used in the embodiment. [Figure 4] FIG. 4 is a schematic diagram showing an electronic voting system according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiment described below. In addition, in each drawing, the same or corresponding elements are appropriately assigned the same reference numerals. Furthermore, it should be noted that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, etc. may differ from the actual ones. There may also be parts in which the dimensional relationship and ratio differ between the drawings.

[0016] [First embodiment] Fig. 1 is a schematic diagram showing an electronic voting system according to the first embodiment. As shown in Fig. 1, the electronic voting system 100 comprises a voting rights management device 110, a voting processing device 120, and secret sharing servers 131, 132, and 133. The electronic voting system 100 is intended to electronicize general elections by transmitting and receiving data to and from an electronic voting terminal 20 where a voter P casts an electronic vote, but can also be applied to general voting that requires the prevention of multiple voting and the guarantee of anonymity, such as anonymous surveys.

[0017] The voting rights management device 110 issues a voting ID to the voter P based on the voter list. The voting ID is assumed to be a number or a character string, but in a survey or the like, a nickname or a name may be used if privacy and security are permitted. Also, the voting ID may be issued in the form of a barcode, electronic token, or the like, instead of directly issuing a number or a character string.

[0018] The voting processing device 120 receives electronic voting information with a voting ID and voting contents with an electronic signature from the electronic voting terminal 20, verifies the identity of the voter P by comparing the voting ID and voting contents with the electronic signature, and records the voting ID and electronic signature removed from the electronic voting information, i.e., the voting contents, as voting data. The voting contents are the names of candidates in the case of an election, and the answers in the case of a questionnaire.

[0019] Here, an electronic signature is an electronic record attached to an electronic document to certify the creator of that electronic document. In public key cryptography, a typical mechanism for realizing an electronic signature, the electronic document or its hash value is encrypted using a private key known only to the creator of the electronic document. When a ciphertext encrypted with a private key known only to the creator is decrypted with a public key to obtain the original electronic document or its hash value, it proves that the electronic document was created by the correct creator. The voting processing device 120 uses this mechanism to verify the identity of voter P by comparing the voting ID and voting content with the electronic signature.

[0020] After verifying the identity of voter P using the above method, the voting processing device 120 inquires of the voting processing device 120 to confirm whether the voting ID corresponding to voter P has already been voted for, and if the voting ID corresponding to voter P has not already been voted for, the voting processing device 120 changes the voting ID corresponding to voter P to one that has already been voted for, and invalidates the voting ID corresponding to voter P. In this way, the electronic voting system 100 prevents multiple voting.

[0021] In addition, the voting processing device 120 uses the above method to verify the identity of the voter P, and then records the voting details from the electronic voting information as voting data. Since the electronic voting system 100 is intended to be applied to secret voting, a voting ID and electronic signature are not required, and the voting processing device 120 removes the voting ID and electronic signature that may identify the voter P from the electronic voting information and records it as voting data. In this way, the electronic voting system 100 ensures anonymity.

[0022] Meanwhile, the voting processing device 120 secretly shares and records the voting ID, voting contents, and electronic signature in at least three secret sharing servers 131, 132, and 133. Secret sharing is a technique for maintaining secrecy by distributing information that should be kept secret to each participant. Each participant is given information called a share that is generated from the secret information. The number of shares is the same as the number of participants, and the shares are generated so that the original secret information cannot be restored by looking at each individual share, but the secret information can be restored by collecting a sufficient number of shares.

[0023] For example, the simplest method of secret sharing among three secret sharing servers 131, 132, and 133 is to decompose the information a to be kept secret as a=a1+a2+a3mod7, record (a1, a2) in the secret sharing server 131, record (a2, a3) in the secret sharing server 132, and record (a3, a1) in the secret sharing server 133. The information a to be kept secret cannot be restored by the data recorded in each secret sharing server 131, 132, and 133 alone. On the other hand, the secret information a can be restored by combining the data of at least two of the three secret sharing servers 131, 132, and 133. Various methods of such secret sharing are known, and these can be appropriately selected and used depending on the application to which the electronic voting system 100 is applied. In that case, the number of secret sharing servers required may be more than three.

[0024] Moreover, the secret information that has been secretly shared as described above can also be calculated while maintaining secrecy. Generally, calculations that are performed while maintaining secrecy are called secure calculations. This secure calculation is theoretically capable of performing any calculation, because AND and OR calculations can be realized by secure calculation. However, it is cumbersome to break down all calculations into AND and OR calculations, and a secret sharing method suitable for the required secure calculation can be appropriately selected and used.

[0025] As a result, the secret sharing servers 131, 132, and 133 can recount the voting IDs, voting contents, and electronic signatures using secure calculations, and verify the counting results using the voting data counted by the voting processing device 120. Also, the secret sharing servers 131, 132, and 133 can verify the consistency between the voting IDs and the voting IDs issued by the voting rights management device using secure calculations. Furthermore, the secret sharing servers 131, 132, and 133 can also verify the consistency between the voting IDs and voting contents and the electronic signatures using secure calculations. In this way, the electronic voting system 100 of this embodiment can verify that the data recorded in the voting data is appropriate, while preventing multiple voting and ensuring anonymity.

[0026] It is preferable that the communication between the voting processing device 120 and the electronic voting terminal 20 is encrypted according to the security required for the application of electronic voting. If the communication between the voting processing device 120 and the electronic voting terminal 20 is intercepted, there is a risk that the voting contents of the voter P will be leaked. Therefore, when applied to voting that requires a high level of security, it is preferable to apply encryption. It is also possible to encrypt the entire communication between the voting processing device 120 and the electronic voting terminal 20, but if the security of the application allows, it is also possible to encrypt only the voting contents and attach an electronic signature to the encrypted voting contents.

[0027] Fig. 2 is a schematic system flow diagram showing the electronic voting method according to the first embodiment. The electronic voting method shown in Fig. 2 is an electronic voting method using an electronic voting system 100 in which voters transmit and receive data to and from an electronic voting terminal 20 where they vote electronically. The electronic voting system 100 comprises a voting right management device 110, a voting processing device 120, and a secret sharing server 130, and Fig. 2 shows an overview of the processing carried out between the electronic voting terminal 20, the voting right management device 110, the voting processing device 120, and the secret sharing server 130. Note that the secret sharing server 130 is shown as a representative of the secret sharing servers 131, 132, and 133 in Fig. 1, and does not limit the actual number of servers.

[0028] As shown in FIG. 2, in step S1, the voting right management device 110 issues a voting ID to the voter P based on the voter list, and the voting right management device 110 transmits the voting ID to the electronic voting terminal 20.

[0029] Then, in step S2, the voter P uses the electronic voting terminal 20 to attach an electronic signature to the voting ID and voting contents, and transmits the voting ID, voting contents, and electronic signature to the voting processing device 120.

[0030] In step S3, the voting processing device 120 verifies the identity of the voter P by comparing the voting ID and voting contents with the electronic signature.

[0031] After that, in step S4, the voting processing device 120 inquires of the voting processing device 120 to confirm whether the voting ID corresponding to the voter P has already been voted. If the voting ID corresponding to the voter P has not already been voted, the voting processing device 120 changes the voting ID corresponding to the voter P to "voted" and invalidates the voting ID corresponding to the voter P. In this way, the electronic voting system 100 prevents multiple voting.

[0032] Meanwhile, in step S5, the voting processing device 120 records the voting details from the electronic voting information as voting data. In other words, the voting processing device 120 removes the voting ID and electronic signature that may identify the voter P from the electronic voting information, and records them as voting data to ensure anonymity.

[0033] Then, in step S6, the voting processing device 120 transmits the voting ID, the voting content, and the electronic signature to the secret sharing server 130, and the secret sharing server 130 secretly shares and records the voting ID, the voting content, and the electronic signature.

[0034] As described above, the electronic voting method of this embodiment makes it possible to verify that the data recorded in the voting data is appropriate, while preventing multiple voting and ensuring anonymity.

[0035] [Hardware configuration example] FIG. 3 is a diagram showing an example of the hardware configuration of the device used in the embodiment. That is, the voting right management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133 can realize each function of the voting right management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133 by executing the electronic voting method described above as a program in an information processing device (computer) adopting the hardware configuration shown in FIG. 3. However, the hardware configuration example shown in FIG. 3 is an example of a hardware configuration that realizes each function of the voting right management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133, and is not intended to limit the hardware configuration of the voting right management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133. The voting right management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133 can include hardware not shown in FIG. 3.

[0036] As shown in Figure 3, the hardware configuration 10 that can be adopted by the voting rights management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133 includes a CPU (Central Processing Unit) 11, a main memory device 12, an auxiliary memory device 13, and an IF (Interface) unit 14, which are interconnected, for example, by an internal bus.

[0037] The CPU 11 executes each command included in the electronic voting program executed by the voting right management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133. The main storage device 12 is, for example, a RAM (Random Access Memory), and temporarily stores various programs, such as the homomorphic cyclic arithmetic program executed by the voting right management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133, for processing by the CPU 11.

[0038] The auxiliary storage device 13 is, for example, a hard disk drive (HDD), and is capable of storing various programs, such as homomorphic cyclic arithmetic programs executed by the voting rights management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133, for a medium to long term. Various programs, such as the electronic voting program, can be provided as program products recorded on a non-transitory computer-readable storage medium.

[0039] The auxiliary storage device 13 can also store data used in the electronic voting method. That is, the auxiliary storage device 13 can be used to store the voter list in the voting right management device 110, can be used to store the voting data in the voting processing device 120, and can be used for the secret sharing data in the secret sharing servers 131, 132, and 133.

[0040] The IF unit 14 provides an interface for input / output between the voting rights management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133, for example.

[0041] An information processing device employing the above hardware configuration 10 realizes the functions of, for example, the voting rights management device 110, the voting processing device 120, and the secret sharing servers 131, 132, and 133 by executing the above-mentioned electronic voting method as a program.

[0042] [Second embodiment] 4 is a schematic diagram showing an electronic voting system according to the second embodiment. The electronic voting system 200 according to the second embodiment is an embodiment closer to voting in an actual election.

[0043] As shown in Fig. 4, the electronic voting system 200 comprises a voting rights management device 210, a voting processing device 220, and a secret sharing server group 230. The electronic voting system 200 processes electronic voting performed by a voter P using an electronic voting terminal 20, and prevents multiple voting even when the voter P casts a vote using a ballot paper 31 at a polling station 30.

[0044] The voting rights management device 210 issues a voting ID to the voter P based on the voter list. At this time, the voting ID is common to both electronic voting and voting using the ballot paper 31. For example, the voting ID on the ballot paper 31 can be implemented by printing it as a barcode or the like.

[0045] The voting processing device 220 receives electronic voting information with a voting ID and voting contents with an electronic signature from the electronic voting terminal 20, and verifies the identity of the voter P by comparing the voting ID and voting contents with the electronic signature.

[0046] Here, a pair of a private key and a public key issued by a public institution is used for the electronic signature. For example, in Japan, there is a system called My Number Card, and a pair of a private key and a public key issued by a public institution is stored in an IC chip built into this My Number Card. This pair of private key and public key can be used as an electronic signature via a commonly used electronic terminal such as a smartphone. It is preferable to use an electronic signature using a pair of a private key and a public key issued by such a public institution in an electronic voting system for elections as well.

[0047] Furthermore, the voting processing device 220 queries the third-party certification authority 40 to verify that the electronic signature received from the electronic voting terminal 20 is legitimate. Even with the above-mentioned electronic signature, there is a risk that voter P may be spoofed by forging a pair of private key and public key. For this reason, there is a mechanism called public key infrastructure (PKI) for guaranteeing the correspondence between a public key and its owner. Using this mechanism, the voting processing device 220 queries the third-party certification authority 40 to verify that the public key of the voter linked to the voting ID is genuine, and then performs identity verification.

[0048] After verifying the identity of voter P using the above method, the voting processing device 220 inquires of the voting processing device 220 to confirm whether the voting ID corresponding to voter P has already been voted for, and if the voting ID corresponding to voter P has not already been voted for, the voting processing device 220 changes the voting ID corresponding to voter P to one that has already been voted for and invalidates the voting ID corresponding to voter P.

[0049] The voting ID managed by the voting processing device 220 is common to both electronic voting and voting using the ballot paper 31, and when the voting processing device 220 confirms the electronic voting as described above, it will reject the voting using the ballot paper 31 at the polling station 30. Conversely, if voting using the ballot paper 31 has already been performed at the polling station 30, the voting processing device 220 will already have the voting ID corresponding to the voter P voted, and inquiries from the voting processing device 220 to the voting processing device 220 will also indicate that voting has already been performed, so it will be possible to reject the acceptance of the electronic vote. In this way, the electronic voting system 200 prevents multiple voting between electronic voting and voting using the ballot paper 31.

[0050] The voting processing device 220 then removes the voting ID and electronic signature from the electronic voting information, i.e., records the voting details as voting data. The voting processing device 220 keeps the voting data secret until the voting deadline, but it is also possible to make information such as the voting rate at each time public on the dashboard system 50. In addition, once the voting deadline has passed, the voting data does not contain personal information, so it can be made publicly available as open data.

[0051] The voting processing device 220 secretly shares and records the voting ID, voting contents, and electronic signature in the secret sharing server group 230. The mechanism of secret sharing and secure computation in the secret sharing server group 230 is the same as in the first embodiment, so a description thereof will be omitted here.

[0052] The disclosures of the above cited patent documents are incorporated herein by reference. Within the scope of the entire disclosure of the present invention (including the scope of claims), modifications and adjustments of the embodiments and examples are possible based on the basic technical ideas. Furthermore, within the scope of the entire disclosure of the present invention, various combinations or selections (including partial deletions) of various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) are possible. In other words, the present invention naturally includes various modifications and corrections that a person skilled in the art would be able to make in accordance with the entire disclosure including the scope of claims and the technical ideas. In particular, with regard to the numerical ranges described in this specification, any numerical value or small range included in the range should be construed as being specifically described even if not otherwise specified. Furthermore, the disclosures of the above cited documents, if necessary, in accordance with the spirit of the present invention, may be used in part or in whole in combination with the disclosures of this specification as part of the disclosure of the present invention, and are deemed to be included in the disclosures of this application. [Explanation of symbols]

[0053] 100,200 Electronic Voting System 110,210 Voting rights management device 120,220 Voting Processing Device 130,131,132,133 Secret sharing server 230 Secret Sharing Server Cluster 10 Hardware Configuration 11 CPU 12 Main storage 13 Auxiliary storage device 14 IF Section 20 Electronic Voting Terminal 30 polling stations 31 Ballot paper 40 Third Party Certification Authority 50 Dashboard System P Voter

Claims

1. An electronic voting system in which voters transmit and receive information to and from electronic voting terminals where they vote electronically, A voting rights management device that issues a voting ID to the voter based on a voter list; A voting processing device that receives electronic voting information with an electronic signature attached to the voting ID and voting contents from the electronic voting terminal, verifies the identity of the voter by comparing the voting ID and voting contents with the electronic signature, and records the electronic voting information with the voting ID and the electronic signature removed as voting data; at least three secret sharing server devices which secretly share and record the voting ID, the voting contents, and the electronic signature; An electronic voting system comprising:

2. 2. The electronic voting system according to claim 1, wherein the voting right management device invalidates the voting ID based on a result of identity verification in the voting processing device.

3. 3. The electronic voting system according to claim 1, wherein the voting rights management device invalidates the voting ID linked to the ballot paper based on a voting result using the ballot paper at a polling station.

4. The electronic voting system according to any one of claims 1 to 3, wherein the secret sharing server device recounts the voting ID, the voting content, and the electronic signature using secret calculation, and verifies the counting result using the voting data.

5. 5. The electronic voting system according to claim 1, wherein the secret sharing server device verifies the consistency between the voting ID and the voting ID issued by the voting right management device using a secure computation.

6. 6. The electronic voting system according to claim 1, wherein the secret sharing server device verifies the consistency between the voting ID and the voting content and the electronic signature using a secret calculation.

7. The electronic voting system according to any one of claims 1 to 6, wherein the voting processing device performs identity verification after verifying that the voter's public key linked to the voting ID is authentic by inquiring with a third-party certification authority.

8. 8. The electronic voting system according to claim 1, wherein the pair of private key and public key used for the electronic signature is issued by a public institution.

9. An electronic voting method using an electronic voting system in which voters transmit and receive information to and from an electronic voting terminal for electronic voting, The electronic voting system issues a voting ID to the voter based on the voter list; receiving electronic voting information with an electronic signature attached to the voting ID and the voting content from the electronic voting terminal; Verifying the identity of the voter by comparing the voting ID and the voting content with the electronic signature; The electronic voting information is recorded with the voting ID and the electronic signature removed as voting data; the voting ID, the voting content, and the electronic signature are recorded in a secret sharing manner; Electronic voting methods.

10. An electronic voting program to be executed by an electronic voting system that transmits and receives information to and from an electronic voting terminal where a voter performs electronic voting, issuing a voting ID to the voter based on the voter list; receiving electronic voting information with an electronic signature attached to the voting ID and the voting content from the electronic voting terminal; Verifying the identity of the voter by comparing the voting ID and the voting content with the electronic signature; The electronic voting information is recorded with the voting ID and the electronic signature removed as voting data; The voting ID, the voting content, and the electronic signature are recorded in a secret sharing manner. An electronic voting program that executes the above.

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