KR102699628B1 - Electronic voting system which allows anyone to verify verify voting process using voting verification key generated by voting result and method of operating the same - Google Patents

Abstract

An electronic voting system that allows anyone to verify an electronic voting process using a voting verification key generated as a result of an electronic voting is provided, and a method of operating the system. The system includes a voting server that receives an electronic envelope containing a marked electronic ballot paper from a voter terminal; a counting server that receives the electronic envelope from the voting server, counts the votes, and tallies the marked electronic ballot papers; and a verification server that verifies the voting server's reception of the electronic envelope and the counting server's counting, wherein the verification server receives a receipt serial number assigned to each different electronic envelope by the voting server during electronic voting in which the voting server receives the electronic envelope, receives a first voting verification key generated by a voter terminal that has completed electronic voting so as not to expose the electronic ballot paper, and verifies the progress of the electronic voting by comparing the number of the receipt serial numbers with the number of the first voting verification keys provided by the voter terminal that has completed electronic voting.

Description

An electronic voting system that allows anyone to verify the electronic voting process using a voting verification key generated as a result of the electronic voting, and a method of operating the system {ELECTRONIC VOTING SYSTEM WHICH ALLOWS ANYONE TO VERIFY VERIFY VOTING PROCESS USING VOTING VERIFICATION KEY GENERATED BY VOTING RESULT AND METHOD OF OPERATING THE SAME}

The present invention relates to an electronic voting system that enables anyone to verify the electronic voting process using a voting verification key generated as a result of an electronic voting, and an operating method of the system. More specifically, the present invention relates to an electronic voting system that enables anyone to verify the voting process and the voting result using an electronic signature for the voting content, a voting verification key for the voting content, and a verification commit generated from the voting verification key, and a method of operating the system.

Electronic voting has been developed through various technologies since the anonymous voting method using encryption was proposed. In general, electronic voting requires confidentiality (Privacy) in which only the voter knows the correspondence between the voter and the content of the vote; uniqueness of voting rights (Uniqueness) in which each voter has only one vote; election rights authentication (Eligibility) in which only those with voting rights can vote; fairness (Fairness) in which no one can determine their own voting results based on the voting results of others; inability to forge (Integrity) in which the voting results cannot be changed by a third party; and accuracy (Accuracy) in which the counting of voting results must be accurate.

However, although various electronic voting systems have been proposed, there are concerns that voter information may be leaked and vote content may be falsified due to many incomplete parts in the above principles.

The technical problem to be solved by the present invention is to provide an electronic voting system and an operating method thereof, which allows a voter to generate a voting verification key for verifying the voting content based on ballot data in which the voting content is recorded, and a voting server to provide an electronic signature for the voting verification key, thereby allowing all parties, including the voter and a third party, to verify the voting process and the vote counting process.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

According to an embodiment of the present invention for solving the above-described technical problem, an electronic voting system capable of verifying the electronic voting process and result by anyone using a voting verification key generated as an electronic voting result comprises: a voting server which receives an electronic envelope including a marked electronic ballot paper from a voter terminal; a counting server which receives the electronic envelope from the voting server, counts the votes, and tallies the marked electronic ballot papers; and a verification server which verifies the reception of the electronic envelope by the voting server and the counting of the votes by the counting server, wherein the verification server receives a receipt serial number assigned to each different electronic envelope by the voting server during the electronic voting process in which the voting server receives the electronic envelope, receives a first voting verification key generated by a voter terminal that has completed electronic voting so as not to expose the electronic ballot paper, and verifies the progress of the electronic voting by comparing the number of the receipt serial numbers with the number of the first voting verification keys provided by the voter terminal that has completed electronic voting.

In some embodiments of the present invention, the voting server creates an electronic signature for the first voting verification key, and the voter terminal that has completed the electronic voting transmits a verification set of the electronic vote including the first voting verification key and the electronic signature of the first voting verification key to the verification server, and the verification server can verify the validity of the first voting verification key using the electronic signature of the first voting verification key.

In some embodiments of the present invention, the electronic envelope may include the marked electronic ballot, a hash of the marked electronic ballot, an electronic signature created by the voting server for the marked electronic ballot, and a verification commit including a hash of the first voting verification key.

In some embodiments of the present invention, the verification server may store a verification commit generated from a hash of a marked electronic ballot paper of different voter terminals and a first vote verification key during vote counting by the counting server, and after completion of vote counting by the counting server, search for a verification commit corresponding to a second vote verification key provided from any terminal among the verification commits generated from the first vote verification keys of the stored different voter terminals.

In some embodiments of the present invention, the hash of the electronic ballot corresponding to the retrieved verification commit is compared with the hash of the electronic ballot provided from the arbitrary terminal to verify whether the electronic vote of the arbitrary terminal has been counted.

In some embodiments of the present invention, the verification server may receive an electronic signature of the voting server for the second voting verification key from the arbitrary terminal, and may verify the validity of the second voting verification key with the electronic signature of the second voting verification key before retrieving the stored verification commit.

In some embodiments of the present invention, the first voting verification key may include information of arbitrary integers R1, R2 and a hash (H(Vj)) of the electronic ballot paper (Vj).

In some embodiments of the present invention, a verification commit including a hash of the first voting verification key can be generated as H(R1, R2, H(Vj)) || R1.

In some embodiments of the present invention, the voting server, upon receiving the electronic envelope, assigns a receipt serial number corresponding to the electronic envelope, creates an electronic signature on the receipt serial number and transmits the electronic signature together with the receipt serial number to the verification server, and the verification server can compare the number of first voting verification keys of the different voter terminals stored with the number of receipt serial numbers at the time of vote counting by the vote counting server to determine whether the electronic vote is valid.

In some embodiments of the present invention, the counting server transmits the receipt serial number assigned to the electronic envelope at the time of counting to the verification server, and the verification server can search for the receipt serial number provided by the counting server among the receipt serial numbers transmitted from the voting server to verify the validity of the electronic envelope.

In some embodiments of the present invention, the verification server may verify the receipt serial number using an electronic signature for the receipt serial number provided from the voting server.

In some embodiments of the present invention, the voting server may further include an authentication server that generates an authentication result, and the voting server may verify the marked electronic ballot paper and the first voting verification key using the authentication result, and may create an electronic signature of the marked electronic ballot paper and the first voting verification key based on the verification result.

In some embodiments of the present invention, the voting server may create an electronic signature of the marked electronic ballot paper or the first voting verification key using a hidden coefficient or zero-knowledge proof so as not to allow the voter terminal to know the contents of the marked electronic ballot paper or the first voting verification key.

Specific details of other embodiments are included in the detailed description and drawings.

An electronic voting system and its operation method, which enable anyone to verify the electronic voting process and result using a vote verification key generated as an electronic voting result according to an embodiment of the present invention, can verify the voting progress and vote counting result using a vote verification key generated from an electronic ballot on which voting has been completed and a verification commit using a hash of the vote verification key.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

FIG. 1 is a block diagram illustrating an electronic voting system that allows anyone to verify the voting process and results according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating an electronic voting process included in an operation method of an electronic voting system in which anyone can verify the voting process and results according to an embodiment of the present invention.
Figure 3 is a flowchart for explaining the electronic signature steps of the electronic ballot paper and voting verification key of Figure 2.
FIG. 4 is a drawing for explaining an electronic voting result verification process according to an electronic voting system according to an embodiment of the present invention.
FIG. 5 is a diagram for explaining the operation of a verification server included in an electronic voting system according to an embodiment of the present invention.

The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and these embodiments are provided only to make the disclosure of the present invention complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

When a component is referred to as being "connected to" or "coupled to" another component, it includes both the case where it is directly connected or coupled to the other component, or where there are other intervening components. On the other hand, when a component is referred to as being "directly connected to" or "directly coupled to" another component, it indicates that there are no other intervening components. "And/or" includes each and every combination of one or more of the mentioned items.

The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the invention. In this specification, the singular also includes the plural unless the context clearly dictates otherwise. The terms "comprises" and/or "comprising" as used herein do not exclude the presence or addition of one or more other components, steps, operations and/or elements.

Although the terms first, second, etc. are used to describe various components, it is to be understood that these components are not limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, it is to be understood that the first component referred to below may also be a second component within the technical concept of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning that can be commonly understood by a person of ordinary skill in the art to which the present invention belongs. In addition, terms defined in commonly used dictionaries shall not be ideally or excessively interpreted unless explicitly specifically defined.

FIG. 1 is a block diagram for explaining an electronic voting system that allows anyone to verify the electronic voting process and results using a voting verification key generated as an electronic voting result according to an embodiment of the present invention.

Referring to FIG. 1, an electronic voting system (10) that allows anyone to verify the electronic voting process and results according to an embodiment of the present invention may include a voter terminal (100), a voting server (200), a vote counting server (300), a verification server (400), and an authentication server (500).

The electronic voting described in the present invention means an event in which a voter electronically participates using a voter terminal (100) to express his/her intention to choose one of the candidates, including the candidate, and corresponds to a concept that is in contrast to the actual voting performed in reality.

The voter terminal (100) is a user terminal used by voters participating in electronic voting and may include a computing device such as a personal computer (PC), a smartphone, or a tablet PC. The voter terminal (100) may output various user interfaces for conducting electronic voting, and voters may participate in electronic voting and perform a verification process by interacting with the interface.

The voter terminal (100) can connect to the voting server (200) via the network (1000) and transmit an electronic envelope containing an electronic ballot paper on which voting has been completed.

An electronic ballot paper is data expressed electronically to include information about at least one candidate who is the subject of electronic voting, and corresponds to a ballot paper in which the candidate is printed on paper in a physical vote. The electronic ballot paper may be configured in a data format such as JSON, XML, etc., but the present invention is not limited thereto. When a voter selects a candidate through a voter terminal (100), the electronic ballot paper may change its status to an electronic ballot paper in which information about the selected candidate is written and the voting is completed.

The voter terminal (100) can access the verification server (500) through the network (1000) to request verification of the voting status and verification of the vote counting results, and receive the verification results from the verification server (500).

The voter terminal (100) can perform user authentication by connecting to the authentication server (500) via the network (1000) prior to the electronic voting. The voting server (200) can be set so that only the voter terminal (100) that has successfully completed user authentication can participate in the electronic voting.

The verifier terminal (110) is a user terminal used by a verifier who wishes to verify the process and results of electronic voting separately from the voter terminal (100), and may include a computing device similar to the voter terminal (100). The verifier terminal (110) may connect to the verification server (500) through the network (1000) to request verification of the voting status during the voting or vote counting process and verification of the vote counting results after the vote counting is completed, and may receive the verification result by the verification server (500).

The voting server (200), the counting server (300), the verification server (400), and the authentication server (500) are server computers that are connected through the network (1000) of the electronic voting system (10) according to the embodiment of the present invention and can perform data transmission and response according to requests between each component. Each of the servers (200 to 500) may be configured to include at least one computer hardware, and in this specification, each of the servers (200 to 500) is described as being physically/conceptually separated. However, the present invention is not limited thereto, and at least two or more of the servers (200 to 500) included in the electronic voting system (10) may be implemented to be functionally separated within the same server hardware.

The voting server (200) may be a server managed by an organization that oversees the progress of electronic voting, for example, an election management committee (hereinafter referred to as the Election Commission). The voting server (200) may receive and process an electronic envelope for electronic voting from a voter terminal (100). In addition, the voting server (200) may record a receipt serial number on the electronic envelope to perform automatic receipt confirmation, and through this, may verify the receipt serial number with a verification server (400) during the vote counting process to verify whether the corresponding electronic envelope and the electronic ballot paper included in the electronic envelope are valid.

The voting server (200) can generate an electronic signature for the data provided from the voter terminal (100) and send it back. Specifically, the voting server (200) can receive an electronic signature request for the marked electronic ballot paper and the voting verification key data from the voter terminal (100), create an electronic signature for the electronic ballot paper and the voting verification key, and transmit them to the voter terminal (100). Such an electronic signature for the electronic ballot paper and the voting verification key is for preventing forgery and denial of signature from both the voter terminal (100) that participated in the electronic vote and the voting server (200) that received the electronic ballot envelope from the voter terminal (100) (i.e., provided the electronic signature).

Meanwhile, when the voting server (200) transmits data such as a marked electronic ballot paper to request an electronic signature, in order to maintain the confidentiality of electronic voting, the voting server (200) can generate an electronic signature for the corresponding data without knowing the contents of the electronic ballot paper and the voting verification key data. The voting server (200) can generate an electronic signature without knowing the contents of the target data, for example, by using a hidden coefficient or a zero-knowledge proof.

The verification server (400) receives data for verification generated during the electronic voting process from a voter terminal (100) or a voting server (200), and anyone, including the voter's own voter terminal (100) or a verifier terminal (110) performing verification, can perform verification on a request for verification of the electronic voting process and results, and transmit the results.

The verification server (400) may be provided with a verification set of an electronic ballot paper in order to obtain the result of participation in electronic voting of a voter terminal (100). The verification set of an electronic ballot paper transmitted by a voter terminal (100) may include a vote verification key and an electronic signature of a voting server (200) for the vote verification key. The verification set of an electronic ballot paper transmitted from a voter terminal (100), particularly, the vote verification key of the voter terminal (100), may be used to generate and verify a real-time tally of voters during voting, and may also be used to verify the vote counting result by a voter terminal (100) or a verifier terminal (110) that presents a vote verification key after vote counting. The verification server (400) may directly receive the verification set of the electronic ballot paper from the voter terminal (100), but is not limited thereto, and the verification set of the electronic ballot paper may be transmitted from the voter terminal (100) to the verification terminal (400) through the voting server (200) along with the transmission of the electronic envelope.

During the voting process, the verification server (400) can store the receipt serial number of the electronic envelope generated by automatic receipt of the electronic envelope from the voting server (200). The receipt serial number of the electronic envelope is recorded by the voting server (200) in the electronic envelope received during the electronic voting process, and the verification server (400) can verify the validity of the corresponding ballot paper by comparing it with the receipt serial number read and transmitted from the electronic envelope by the vote counting server (300) when counting after the completion of the electronic voting.

In addition, the verification server (400) can verify the vote counting results. To this end, the verification server (400) can use the verification commit collected from the electronic envelope by the vote counting server (300) during vote counting and the hash of the electronic ballot. When the voter terminal (100) or the verifier terminal (110) that wants to verify the vote counting results presents a vote verification key, the verification server (400) generates a verification commit from the presented vote verification key and verifies whether there is a verification commit that matches among the verification commits received and stored from the vote counting server (300) and whether the hash of the corresponding marked electronic vote matches, thereby verifying the vote counting results.

The authentication server (500) can authenticate the voter terminal (100) connected to the voting server (200). For example, the authentication server (500) can perform a process such as real-name authentication using the voter's mobile phone number, authentication using personal information such as the resident registration number, or biometric authentication using the voter's biometric information to perform identity authentication of the voter. In some embodiments, the authentication server (500) can provide the voter's identity authentication result to the voter terminal (100).

FIG. 2 is a flowchart for explaining an electronic voting process included in an operation method of an electronic voting system (100) that allows anyone to verify the voting process and results according to an embodiment of the present invention.

Referring to FIG. 2, the operation method of the electronic voting system that allows anyone to verify the voting process and results of the present invention includes a step (S110) of performing user authentication of a voter terminal at an authentication server, a step (S120) of the voting server receiving a marked electronic ballot and a voting verification key from the voter terminal (100) and writing an electronic signature on the marked electronic ballot and the voting verification key and sending it back, a step (S130) of the voting server receiving a verification set of the electronic ballot and an electronic envelope of the electronic ballot from the voter terminal (100), a step (S140) of the voting server recording a receipt serial number in the electronic envelope and storing the verification set of the electronic ballot in the verification server, a step (S150) of the vote-counting server reading the marked electronic ballot included in the electronic envelope and proceeding with the vote-counting, and a step (S160) of the verification server storing a verification commit included in the electronic envelope and a hash of the electronic ballot.

First, a step (S110) is performed to perform user authentication of the voter terminal on the authentication server.

The authentication server (500) may be, for example, an authentication server of an external authentication agency or a server of a public authentication agency, or may be connected to the above servers, and may perform identity verification of a voter using a voter terminal (100) by a designated identity verification method. For example, the authentication server (500) may perform real-name authentication using the voter's mobile phone number to perform identity verification of the voter, or may perform authentication using a challenge-response technique in which a hash of personal information such as a resident registration number is stored in the authentication server (500) but password information is not stored. If authentication is successful, the authentication server (500) may electronically sign the authentication result with the private key of the authentication server (500) and transmit it to the voter terminal (100). This authentication result may be verified by the voting server (200) using the public key of the authentication server (500) in the subsequent voting stage, thereby verifying whether the user has been authenticated.

In some embodiments of the present invention, a step of issuing private keys and public keys of the voting server (200) and the vote counting server (300) may be performed prior to the identity authentication step.

When authentication is completed, a step (S120) is performed in which the voter marks an electronic ballot paper at the voter terminal (100), the voting server (200) receives the marked electronic ballot paper and the voting verification key from the voter terminal (100), and writes an electronic signature on the marked electronic ballot paper and the voting verification key and sends a reply. This will be explained using FIG. 3.

Figure 3 is a flowchart for explaining the electronic signature steps of the electronic ballot paper and voting verification key of Figure 2.

Referring to FIG. 3, when a voter completes voting by selecting one of the candidates output through the voter terminal (100), the voter terminal (100) can generate an electronic ballot paper (Vj) on which voting is completed (S210). The voter terminal (100) transmits the electronic ballot paper (Vj) on which voting is completed to the voting server (200) in order to receive an electronic signature from the election commission for the electronic ballot paper (Vj) on which voting is completed (S220). However, a method using a hidden coefficient or a zero-knowledge proof can be used to keep the voting content secret from the voting server (200).

First, to explain the method of using a hidden coefficient, the voter terminal (100) multiplies the marked electronic ballot paper (Vj) by a hidden coefficient (bk) and performs modular calculation to generate a hidden electronic ballot paper (B).

B = Vj * bk ^pubv (mod n) (where pubv is the public key of the voting server (200))

The voter terminal (100) can transmit a hidden electronic ballot paper (B) to the voting server (200). At this time, the voter terminal can transmit the authentication result transmitted from the authentication server (500) together with the hidden electronic ballot paper (B), and the voting server (200) can verify the electronic voting qualification of the voter terminal (100) by verifying the authentication result using the public key of the authentication server (500) (S230).

When the electronic voting qualification of the voter terminal (100) is confirmed, the voting server (200) can electronically sign (B _s ) the hidden electronic ballot paper (B) and send it to the voter terminal (100) (S240).

B _s = B ^skv (mod n) (where skv is the private key of the voting server (200))

The voter terminal (100) can obtain an electronic signature of a marked electronic ballot paper (Vj) by dividing and removing the hidden coefficient bk from the electronically signed hidden electronic ballot paper (B _s ).

B ^skv / bk (mod n) = (Vj * bk ^pubv ) ^skv / bk (mod n) = Vj ^skv (mod n)

Meanwhile, when obtaining an electronic signature of a voting server (200) by a zero-knowledge proof method, a request can be made through commit, nizk (proof), nonce, etc. As described above, even when obtaining an electronic signature by a zero-knowledge proof in order to maintain confidential voting for the voting server (200), the user terminal (100) can transmit a marked electronic ballot paper while hiding it without transmitting the actual electronic ballot paper.

Specifically, the voter terminal (100) can create a zero-knowledge proof and transmit it to the voting server (200). The proof is data that can prove that it was created from an actually marked electronic ballot paper (Vj), and the voting server (200) verifies the zero-knowledge proof, and when verification is completed, an electronic signature can be created and pre-electronic signature data can be returned to the voter terminal (100). The voter terminal (100) can complete an electronic signature for the marked electronic ballot paper (Vj) by using the marked electronic ballot paper (Vj) used to create the pre-electronic signature and proof returned by the voting server (200).

Meanwhile, the voter terminal (100) can generate a vote verification key and obtain an electronic signature for the vote verification key from the voting server (200) (S250). The vote verification key corresponds to information that the voter terminal (100) that conducted the electronic vote and the verifier terminal (110) that verifies whether the electronic vote has been counted and tabulated from a third party's perspective present to the verification server (400) to perform verification. The voter terminal (100) is prevented from denying the fact that it participated in the electronic vote by the electronically signed vote verification key, and the same applies to the voting server (200) that granted the electronic signature.

The vote verification key can be generated, for example, using random integers R1, R2 and a hash (H(Vj)) of a marked electronic ballot. The vote verification key is configured by concatenating, for example, random integers R1, R2 and a hash (H(Vj)) of a marked electronic ballot, and encoding for data transmission may be additionally performed. Since the marked electronic ballot (Vj) is not included in the vote verification key, even if a person other than the voter receives the vote verification key or a verification commit generated from the vote verification key described below, the vote content cannot be known.

Similar to the step of obtaining an electronic signature for an electronic ballot paper (Vj) on which a mark has been completed from the voting server (200), the voter terminal (100) can obtain an electronic signature of the voting verification key from the voting server (200) without exposing the specific content of the voting verification key to the voting server (200) by using a hidden coefficient or zero-knowledge proof method. The voting server (200) can determine whether the voting verification key transmitted from the voter terminal (100) is an electronic signature based on the verification result of the authentication result by the authentication server (500), for example (S260), and can return the result to the voter terminal (100).

When the voter terminal (100) obtains an electronic signature of a voting verification key from a voting server (200), it can generate a verification commit from the voting verification key and configure an electronic envelope of an electronic ballot paper including the verification commit. The verification commit can be generated, for example, by concatenating a hash of the voting verification key and an arbitrary integer R1 as (H(R1, R2, H(Vj)) || R1), and the electronic envelope of the electronic ballot paper can be generated as follows including a marked electronic ballot paper (Vj), an electronic signature of the marked electronic ballot paper (Vj ^svk ), and a verification commit.

Vj || Vj ^svk || (H(R1, R2, H(Vj) || R1)

In addition, the voter terminal (100) may encrypt the electronic envelope with the public key of the vote counting server (300) to ensure the confidentiality of the electronic envelope. In some embodiments of the invention, the voter terminal (100) may use a dual encryption method in which an arbitrary symmetric key is generated, the electronic envelope is encrypted using the generated symmetric key, and the symmetric key is encrypted with the public key of the vote counting server (300) generated by the voter terminal (100). The generated electronic envelope may be transmitted to the voting server (200).

Meanwhile, the voter terminal (100) can configure an electronic envelope as described above, and at the same time, configure a verification set of an electronic ballot paper using the electronic signature of the vote verification key and the vote verification key (R1, R2, H(Vj)), and transmit it to the verification server (400) (S130). Since the verification server (400) cannot know whether the vote verification key (R1, R2, H(Vj)) provided by the voter terminal (100) has been processed or modified, the vote verification key (R1, R2, H(Vj)) can be verified using the electronic signature of the provided vote verification key.

When verification is completed, the verification server (400) can store the verification set of the electronic ballot paper provided from the voter terminal (100) (S140).

The voting server (200) can receive the electronic envelope of the electronic ballot paper transmitted from the voter terminal (100) (S130) and record the receipt serial number on the electronic envelope to perform automatic receipt confirmation (S140). The receipt serial number can be assigned differently for each electronic envelope received by the voting server (200). The receipt serial number can be used to confirm whether the corresponding electronic ballot paper was transmitted from the voter server (100) and correctly received by the voting server (200) when counting electronic votes.

The voting server (200) can assign an electronic signature to the generated receipt serial number and transmit it to the verification server (400). The verification server (400) stores the receipt serial number and the electronic signature assigned thereto, and when counting electronic votes, can determine whether the corresponding electronic ballot paper is valid or invalid by responding to a verification request from the counting server (300) with a matching receipt serial number.

The vote counting server (300) can open the electronic envelope provided from the voting server (200) and proceed with the vote counting (S150). The vote counting server (300) can count the number of electronic envelopes received from the voting server (200) and, prior to the start of the vote counting, compare the total number of vote verification keys stored in the verification server (400) to determine whether all electronic envelopes required for the vote counting have been validly stored. If the number of electronic envelopes received and the total number of vote verification keys stored in the verification server (400) are different, the vote counting server (300) can determine that there is an error in the reception of the electronic envelope by the vote counting server (300) or the reception of the vote verification key by the verification server (400) and stop the vote counting.

In addition, the counting server (300) can use the receipt serial number to determine whether the electronic envelope is valid. That is, as a process of checking whether the receipt serial number automatically recorded in the electronic envelope by the voting server (200) is stored in the verification server (400), the counting server (300) can transmit the receipt serial number recorded in the electronic envelope to the verification server (400) to request verification of the validity of the receipt serial number. The verification server (400) can search for whether the receipt serial number provided by the counting server (300) exists among the receipt serial numbers provided and stored from the voter terminal (100), and can reply that the receipt serial number is valid if it is found, and invalid if it is not found. The counting server (300) can proceed with the counting of the electronic envelope if it is confirmed that the receipt serial number is valid, and can record the electronic envelope as invalid if it is invalid. At this time, the counting server (300) may additionally verify the electronic signature of the receipt serial number.

If the number of electronic envelopes matches the number of vote verification keys, the vote counting server (300) can proceed with vote counting using the electronic envelope. That is, the vote counting server (300) can open the electronic envelope, which may mean a process of decrypting the encrypted electronic envelope using the private key of the vote counting server (300) and obtaining data such as the marked electronic ballot included in the electronic envelope. As described above, the electronic envelope of the electronic ballot includes a marked electronic ballot (Vj), an electronic signature of the marked electronic ballot (Vj ^svk ), and a verification commit (H(R1, R2, H(Vj)) || R1), and the vote counting server (300) can obtain each piece of data from the electronic envelope.

Thereafter, the counting server (300) can verify the electronic signature (Vj ^svk ) of the electronic ballot and count the electronic ballot. In addition, the hash (H(Vj)) of the electronic ballot can be generated and transmitted to the verification server (400) together with the verification commit (H(R1, R2, H(Vj)) || R1). The verification server (400) can store the hash (H(Vj)) of the electronic ballot and the verification commit (H(R1, R2, H(Vj)) || R1) provided from the counting server (300).

At this time, the vote counting server (300) can obtain information on the electronic ballot paper (Vj) on which the marking is completed and the verification commit (H(R1, R2, H(Vj)) || R1), but cannot obtain information on the random integers R1 and R2 used to generate the verification commit (or voting verification key). Therefore, the vote counting server (300) cannot tamper with the contents of the verification commit, and the verification server (300) can confirm the integrity of the verification commit when verifying the vote counting result.

FIG. 4 is a drawing for explaining an electronic voting result verification process according to an electronic voting system according to an embodiment of the present invention.

Referring to FIG. 4, the verification server (400) receives and stores a verification set (a voting verification key and an electronic signature of the voting server (200) for the voting verification key) of an electronic ballot paper from a voter terminal (100) until electronic voting is initiated and vote counting is completed, receives and stores a receipt serial number created by the voting server (200) and an electronic signature of the receipt serial number, and receives and stores a hash (H(Vj)) of an electronic ballot paper and a verification commit (H(R1, R2, H(Vj)) || R1) from the vote counting server (300).

The verification server (400) can verify the number of voters who have completed electronic voting during electronic voting. Specifically, the verification server (400) can compare the number of verification sets of electronic ballot papers received from the voter terminal (100) with the number of receipt serial numbers received from the voting server (200), and output the result.

The verification server (400) can verify whether the electronic votes are counted using the presented vote verification key during or after the completion of the vote counting. When the verification server (400) receives the vote verification key from the voter terminal (100) or the verifier terminal (110), it can generate a verification commit from the vote verification key and search for whether there is a verification commit received from the vote counting server (300) and stored in advance. This will be explained using Figure YY.

FIG. 5 is a diagram for explaining the operation of a verification server included in an electronic voting system according to an embodiment of the present invention.

Referring to FIG. 5, verification of the vote counting results by the verification server includes a step of receiving a second voting verification key from a voter terminal or a verifier terminal (S410), a step of generating a verification commit from the second voting verification key (S420), a step of searching for a verification commit generated among the verification commits transmitted from the voter terminal (100) and stored in advance (S430), and a step of comparing a hash of an electronic ballot paper stored together with the searched verification commit with a hash of an electronic ballot paper held by a terminal that provided the second voting verification key (S440).

First, the verification server (400) performs a step (S410) of receiving a second voting verification key and an electronic signature of the second voting verification key from the voter terminal (100) or the verifier terminal (110). In this embodiment, the voting verification key generated by each voter terminal (100) in the voting step and stored in the verification server (400) is described as the first voting verification key, and the voting verification key received from the voter terminal (100) or the verifier terminal (110) for verification is described as the second voting verification key. As described above, the second voting verification key only includes a hash of the marked electronic ballot paper, so the content of the electronic vote is not exposed.

The verification server (400) can verify the second voting verification key using the electronic signature of the second voting verification key (S411). From the perspective of the verification server (400), it is impossible to know whether the second voting verification key presented by any voter terminal (100) or verifier terminal (110) has been processed or modified, so this is a process of verifying the authenticity of the second voting verification key using the electronic signature provided together.

As a result of the verification, if the second voting verification key is determined to be valid, the verification server (400) generates a verification commit from the second voting verification key (S420). A verification commit of H(R1, R2, H(Vj)) || R1 is generated from the second voting verification key, which is composed of random integers R1, R2, and a hash (H(Vj)) of the marked electronic ballot paper.

The verification server (400) searches for a verification commit (H(R1, R2, H(Vj)) || R1) generated from among the verification commits transmitted and stored in advance from the voter terminal (100) (S430). The verification commits stored in advance correspond to verification commits corresponding to the first voting verification keys provided by different voter terminals (100). When a verification commit is searched, the verification server (400) compares the hash of the electronic ballot paper stored together with the searched verification commit with the hash of the electronic ballot paper held by the terminal providing the second voting verification key (S440). The verification server (400) can detect whether the hash has changed when the verification commit is generated with the hash of the first voting verification key by comparing the hash of the electronic ballot paper.

If the hashes of the two electronic ballots match as a result of the comparison, it means that the electronic vote corresponding to the second voting verification key has been counted by the vote counting server (300) and stored in the verification server (400), so the verification server (400) can output the result of successful verification to the terminal (100, 110) that presented the second voting verification key.

Although the embodiments of the present invention have been described with reference to the attached drawings, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical idea or essential features thereof. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

10: Electronic Voting System 100: Voter Terminal
110: Verifier Terminal 200: Voting Server
300: Counting server 400: Verification server
500: Authentication Server

Claims (10)

A voting server that receives an electronic envelope containing a marked electronic ballot paper from a voter's terminal;
A counting server that receives the electronic envelope from the voting server, counts the votes, and tallies the marked electronic ballot papers; and
Including a verification server that verifies the receipt of the electronic envelope of the above voting server and the counting of the votes of the above counting server,
The above verification server is in the process of electronic voting, where the above voting server receives the electronic envelope.
The voting server receives a receipt serial number assigned to each electronic envelope received from different voter terminals,
The voter's terminal that has completed electronic voting receives and stores the first voting verification key generated to prevent the electronic ballot paper from being exposed.
Verifies the progress of electronic voting by comparing the number of the above-mentioned receipt serial numbers with the number of the first voting verification keys provided by the voter terminal that completed the above-mentioned electronic voting.
Electronic voting system. In the first paragraph,
The above voting server creates an electronic signature for the above first voting verification key,
The voter terminal that has completed the above electronic voting transmits a verification set of the electronic voting, including the first voting verification key and the electronic signature of the first voting verification key, to the verification server,
The above verification server verifies the validity of the first voting verification key using the electronic signature of the first voting verification key.
Electronic voting system. In paragraph 1,
The electronic envelope includes the marked electronic ballot, an electronic signature created by the voting server for the marked electronic ballot, and a verification commit including a hash of the first voting verification key.
Electronic voting system. In the third paragraph,
The above verification server stores a verification commit generated from a hash of the marked electronic ballot papers of different voter terminals and a first voting verification key when counting by the above counting server,
After the counting is completed by the above counting server, a verification commit corresponding to the second voting verification key provided from any terminal among the verification commits generated from the first voting verification keys of the different voter terminals stored above is searched,
Verifies whether the electronic vote of the arbitrary terminal is counted by comparing the hash of the electronic ballot corresponding to the above searched verification commit with the hash of the electronic ballot provided from the arbitrary terminal.
Electronic voting system. In paragraph 4,
The above verification server,
The electronic signature of the voting server for the second voting verification key is provided together with the above arbitrary terminal,
Before retrieving the stored verification commit, the validity of the second voting verification key is verified by the electronic signature of the second voting verification key.
Electronic voting system. In paragraph 5,
The above first voting verification key includes information on random integers R1, R2 and the hash (H(Vj)) of the electronic ballot paper (Vj).
Electronic voting system. In paragraph 6,
A verification commit containing a hash of the above first voting verification key
H(R1, R2, H(Vj)) || R1
is generated by,
Electronic voting system. In paragraph 1,
The above voting server creates an electronic signature on the receipt serial number corresponding to each electronic envelope and transmits it to the verification server together with the receipt serial number.
The above verification server determines whether the electronic vote is valid by comparing the number of first voting verification keys of the voter's terminal that completed the electronic vote with the number of the receipt serial number when the vote is counted by the above counting server.
Electronic voting system. In paragraph 1,
Further comprising an authentication server that generates authentication results,
The above voting server verifies the marked electronic ballot paper and the first voting verification key using the above authentication result, and creates an electronic signature of the marked electronic ballot paper and the first voting verification key based on the above verification result.
Electronic voting system. In paragraph 1,
The above voting server creates an electronic signature of the marked electronic ballot paper or the first voting verification key using a hidden coefficient or zero-knowledge proof so that the voter terminal does not know the contents of the marked electronic ballot paper or the first voting verification key.
Electronic voting system.