KR20200008413A - Terminal device and Server for performing electronic voting based on a block chain ensuring secret election, and Electronic voting method - Google Patents

Abstract

Disclosed are a terminal device performing an electronic vote based on a blockchain guaranteeing a secret vote, a server thereof, and a method for an electronic vote. The disclosed terminal device comprises: a memory unit storing a command which is readable by a computer; and a processor unit which is embodied to execute the command. Here, the processor unit: calculates a serial number corresponding to voting rights by using a secret key of an inputted voter and a common random value to recognize a specific election; calculates an encoded vote result value by encoding the vote result value performed by using the serial number by a common encryption key; calculates a verification value to verify that a secret value is known without releasing the secret value including the secret key of the voter and the vote result value by using a zk-SNARK algorithm; and records the serial number, the encoded vote result value, and the verification value in a blockchain.

Description

Terminal device and server for performing electronic voting based on a block chain ensuring secret election, and Electronic voting method}

Embodiments of the present invention relate to a blockchain-based electronic voting method that guarantees confidentiality and guarantees demediation and forgery of the blockchain, and a terminal device and a server performing the same.

Blockchain is an open common book management technology that distributes and stores data, ensuring transaction transparency. Some recent studies have focused on blockchain demediation and forgery and impossibility, but have applied general blockchain technology that provides transparency in transactions to electronic voting that needs to ensure secret elections. It is not appropriate.

1 is a diagram illustrating the concept of a conventional blockchain based online voting system hosted by the Central Election Commission.

Referring to FIG. 1, since the conventional online voting system establishes electronic voting based on a general blockchain rather than a blockchain that can guarantee privacy, there are many problems in terms of privacy and forgery.

First, the encrypted voting records that voters record on the blockchain are decrypted by the voting server and the ballot counting server, and the server of the election commission trusts it entirely. However, if the server is attacked, there is ample forgery of voting results.

Second, since the voting records listed on the blockchain are stored in a form that includes voter information, the voting server and the counting server capable of decrypting the encrypted voting records can fully know the voting results of each voter. This means that a complete secret election cannot be guaranteed within electronic voting, and there is a risk that the results of all voters' votes will be revealed if the server is attacked.

In order to solve the problems of the prior art as described above, the present invention provides a blockchain-based electronic voting method and a terminal device and a server performing the same to ensure the confidentiality while ensuring the de-intermediation and forgery of the blockchain I would like to suggest.

Other objects of the present invention may be derived by those skilled in the art through the following examples.

According to a preferred embodiment of the present invention for achieving the above object, a terminal device provided in the polling place, and performs an electronic ballot using a block chain, comprising: a memory unit for storing a computer-readable command; And a processor unit configured to execute the command, wherein the processor unit calculates a serial number corresponding to a voting right by using an input voter's secret key and a common random value for identifying a specific election, Encrypt the voting result value performed using the number with a public encryption key to calculate an encrypted voting result value, and know the secret value without revealing the secret value including the voter's secret key and the voting result value. A terminal device is provided which calculates an attestation value for attestation and records the serial number, the encrypted voting result value and the attestation value in the blockchain.

The public cryptographic key, the public random value, and the voter list are recorded in the blockchain, wherein the voter list includes voter information of each of the voters, and the voter information may correspond to a hash value using the secret key of the voter. Can be.

The public cryptographic key, the public random value, and the voter list are calculated by the server of the election management committee and recorded in the blockchain, and the voter information is calculated by the terminal device of the voter and transmitted to the server of the election management committee. Can be registered.

The processor may determine whether voter information input by the voter and voter information recorded in the blockchain are the same.

The processor unit may verify the signature value received from the server of the election administration committee using the voter information input by the voter and the signature key received from the server of the election administration committee.

In addition, according to another embodiment of the present invention, a server provided in the election management committee, and performs the electronic voting by using a block chain, comprising: a memory unit for storing a computer-readable instructions; And a processor unit implemented to execute the instructions, wherein the processor unit generates a common random value for identifying a specific election and a public encryption key for voting, and is received from each of the plurality of voter terminal devices. Generate a voter list using voter information, record the voter list, the public random value, and the public cryptographic key in the blockchain, and sign the voter information using a signature key and the signature key. Transmits to the terminal device provided in the polling place, wherein the terminal device provided in the polling place verifies the transmitted signature value by using voter information inputted by a voter and the transmitted signature key. do.

Further, according to another embodiment of the present invention, in the electronic voting method performed in conjunction with the terminal device A of the voter, the terminal device B provided in the polling place and the server provided in the election management committee, the terminal device A, Generating voter information corresponding to the secret key of the voter and transmitting the voter information to the server; Recording, by the server, on the blockchain a list of voters generated using the transmitted voter information, a public random value for identifying a specific election, and a public encryption key for voting; The terminal device B calculates a serial number corresponding to a voting right using a voter's secret key input from a voter and a shared random value recorded in the blockchain, and shares the voting result value performed using the serial number. Encrypting with an encryption key to calculate an encrypted voting result value, calculating a proof value certifying that the secret value is known without disclosing the secret value including the voter's secret key and the voting result value, the serial number Recording the encrypted voting result value and the attestation value in a blockchain; And registering, by the server, a decryption key for decrypting the encrypted voting result value in the blockchain.

The electronic voting method according to the present invention has an advantage of ensuring confidentiality and guaranteeing de-intermediation and forgery forgery.

In addition, the effect of this invention is not limited to the above-mentioned effect, It should be understood that it includes all the effects which can be inferred from the structure of the invention described in the detailed description of this invention, or a claim.

1 is a diagram illustrating the concept of a conventional blockchain based online voting system hosted by the Central Election Commission.
2 is a diagram illustrating a schematic configuration of an electronic voting system using a blockchain according to an embodiment of the present invention.
3 is a diagram illustrating a schematic configuration of a plurality of terminal devices A, a server, and a plurality of terminal devices B according to an embodiment of the present invention.
4 is a diagram illustrating the concept of an electronic voting method according to an embodiment of the present invention.
5 is a flowchart illustrating an electronic voting method according to an embodiment of the present invention.
6 is a view for explaining the concept of zk-SNARK according to the present invention.

As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise. In this specification, terms such as “consisting of” or “comprising” should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or some steps It should be construed that it may not be included or may further include additional components or steps. In addition, the terms "... unit", "module", etc. described in the specification mean a unit for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software. .

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating a schematic configuration of an electronic voting system using a blockchain according to an embodiment of the present invention.

2, the electronic voting system 200 according to an embodiment of the present invention is a server provided in a plurality of voter terminal device 210 (hereinafter referred to as "terminal device A"), the election management committee And a terminal device 230 (hereinafter, referred to as "terminal device B") provided in the plurality of polling places. In addition, the electronic voting is performed by the plurality of terminal device A 210, the server 220, and the terminal device C 230 interworking with each other.

The plurality of terminal devices A 210 performs a voter registration process and a counting process, and the server 220 interworks with the plurality of terminal devices A 210 and the terminal device B 230 and initiates an election. The terminal device B 230 performs a voting process.

In this case, each of the plurality of terminal apparatuses A 210, the server 220, and the plurality of terminal apparatuses B 230 is a communication unit 310, a memory unit 320, and a processor unit 330 as shown in FIG. 3. ) And a display unit 340.

The communication unit 310 performs a communication connection with an external device.

The memory unit 320 may be a volatile and / or nonvolatile memory, and stores instructions or data related to the terminal device 210 or 230 or at least one other component of the server 220. In particular, the memory unit 320 may store instructions or data related to a computer program or a recording medium required to perform an electronic voting.

The processor unit 330 may include one or more of a central processing unit, an application processor, or a communication processor. In particular, the processor unit 330 may execute instructions related to the execution of the computer program.

The display unit 340 may be configured of a liquid crystal display (LCD), a light emitting diode display (LED), an organic light emitting diode display (OLED), and the like, and may output an execution screen of a computer program executed in the processor 340. .

Hereinafter, an embodiment of an electronic voting method performed in the electronic voting system will be described with reference to FIGS. 4 and 5.

4 is a view illustrating a concept of an electronic voting method according to an embodiment of the present invention, Figure 5 is a flow chart of the electronic voting method according to FIG.

4 and 5 illustrate a process of electronic voting for one voter for convenience of description, and the contents of FIGS. 4 and 5 may be equally applied to all voters.

First, steps 502 to 508 correspond to the "vote registration" process. Hereinafter, the process performed for each step will be described.

를 단말 장치 A(210)로 전송한다. 즉, 유권자는 자신의 ID(일례로, 주민등록번호)를 서버(220)로 입력하고, 유권자의 ID와 일대일로 대응되는 비밀 키

를 랜덤으로 선택하여 부여받는다. 이 때, 서버(220)는 전송된 비밀 키

를 저장하지 않으며, 따라서 비밀 키

는 유권자만이 알 수 있는 정보이다. In step 502, server 220 obtains the voter's secret key.

Is transmitted to the terminal device A (210). That is, the voter enters his or her ID (for example, a social security number) into the server 220, and the secret key corresponds one-to-one with the voter's ID.

Is randomly chosen. At this time, the server 220 is transmitted secret key

Does not store it, and therefore the secret key

Is information that only voters know.

를 이용하여 유권자 정보

를 산출한다. 이 때, 유권자 정보

는 공개된 유권자에 대한 정보로서, 비공개된 비밀 키

와 일대일로 대응되는 정보이다. In step 504, the terminal device A 210 stores the secret key.

Voter Information Using

To calculate. Voter information at this time

Is a publicly held voter's information.

And one-to-one correspondence.

및 유권자 정보

가 산출될 수 있다. According to an embodiment of the present invention, the secret key using Equation 1 below

And voter information

Can be calculated.

는 정수 값의 그룹을 의미한다. 즉, 유권자 정보

는 유권자의 비밀 키

를 이용한 해쉬 값과 대응된다. here,

Means a group of integer values. Voter information

Voter secret key

Corresponds to the hash value using

를 서버(220)로 전송한다. 이 때, 서버(220)는 유권자의 ID 및 이에 대응되는 유권자 정보

를 등록한다. In step 506, terminal device A 210 receives voter information.

To the server 220. At this time, the server 220 voter ID and voter information corresponding thereto.

Register.

가 포함된 유권자 리스트를 블록 체인에 기록한다. 이 때, 블록 체인은 모든 유권자가 접근할 수 있으며, 유권자 리스트는 모든 유권자에 대한 유권자 정보

를 포함한다. In step 508, server 220 obtains voter information.

Writes a list of voters that contains the blockchain. At this point, the blockchain is accessible to all voters, and the list of voters lists voter information for all voters.

It includes.

Next, step 510 and step 512 are steps corresponding to "election start". Hereinafter, the process performed for each step will be described.

및 투표 수행을 위한 공용 암호 키

를 블록 체인에 기록한다. 이 때, 공용 암호 키

는 투표 결과 값을 암호화할 수 있는 키이다. In step 510, server 220 forms a ballot data form, a public random value for identifying a particular election.

Encryption key for conducting votes and voting

Write to the blockchain. At this time, the public encryption key

Is a key that can encrypt the voting result value.

에 대해 서명을 수행하는 서명 키

를 생성한다. 이 때, 서명 키

는 유권자의 비밀 키

가 유출되는 경우, 타인의 비밀 키

로 투표권을 행사하는 것을 방지하기 위해 이용되는 키이다. In step 512, server 220 obtains voter information.

Signing key to sign against

Create At this time, the signing key

Voter secret key

If it is leaked, someone else's secret key

This key is used to prevent voting rights.

Subsequently, the steps 514 to 528 correspond to "vote vote" performed in the terminal device B 230 provided in the polling place. Hereinafter, a process performed for each step will be described in detail.

및 블록 체인에 기록된 공용 랜덤 값

을 이용하여 투표권과 대응되는 일련번호

를 산출한다(

). 즉, 일련번호

는 투표를 행사할 수 있는 권리와 대응된다. In step 514, the terminal device B 230 is a voter's secret key input via a keyboard or the like

And shared random values written to the blockchain

Serial number corresponding to voting right using

Yields

). That is, serial number

Corresponds to the right to cast a ballot.

를 이용하여 투표 결과 값을 산출한다. 그리고, 단계(518)에서, 단말 장치 B(230)는 블록 체인에 기록된 공용 암호 키

로 투표 결과 값을 암호화하여 암호화된 투표 결과 값

을 산출한다(

). In step 516, the terminal device B 230, under the control of the voter, the serial number

Calculate the result of voting using. And, in step 518, the terminal device B 230 is a public encryption key recorded in the blockchain

The vote result encrypted by encrypting the vote result

Yield (

).

와 블록 체인에 기록된 유권자 정보

가 동일한지 여부를 판단한다(

). 즉, 단계(518)는 유권자 자신이 유권자 리스트 내에 존재한다는 것을 증명하는 단계이다.In step 520, the terminal device B 230, voter information input by the voter through a keyboard or the like.

Voter Information Written on Blockchain

Determines whether is equal to (

). That is, step 518 is to verify that the voter is present in the voter list.

를 서명 키

로 서명하여 서명 값

를 산출하고, 단계(524)에서, 서버(220)는 서명 키

및 서명 값

를 단말 장치 B(230)로 전송한다. In step 522, server 220 voter information recorded on the blockchain.

Sign the key

The signature value

In step 524, the server 220 generates a signature key.

And signature values

Is transmitted to the terminal device B (230).

및 서버(220)로부터 수신된 서명 키

를 이용하여 서버(220)로부터 수신된 서명 값

을 검증한다(

). 만약 검증이 되지 않는 경우, 유권자는 타인의 비밀 키

를 이용하여 투표를 수행하는 자로 판명되어 투표를 수행할 수 없다. In step 526, the terminal device B 230, voter information entered by the voter

And the signing key received from the server 220

Signature value received from server 220 using

To verify

). If not validated, the voter has a secret key

You cannot vote because you have been identified as a voter.

, 투표 결과 값 및 유권자 정보

을 포함하는 비밀 값을 공개하지 않고 비밀 값을 알고 있음을 증명하는 증명 값

을 산출한다. 이에 따라, 비밀 투표가 수행될 수 있다. 이 때, zk-SNARK(zero-knowledge Succinct Non-interactive Argument of Knowledge) 알고리즘이 사용될 수 있다. 이에 대해 상세하게 설명하면 다음과 같다 In step 528, terminal device B 230 determines the voter's secret key.

, Voting result values and voter information

Proof that proves that you know the secret without revealing the secret

To calculate. Accordingly, secret voting can be performed. At this time, a zk-SNARK (zero-knowledge Succinct Non-interactive Argument of Knowledge) algorithm may be used. This will be described in detail as follows.

의 관계식이 있을 때, 관계식을 계산하기 위해 필요한 비밀 값인

를 드러내지 않고,

을 알고 있음을 증명하는 알고리즘이다. 즉, 미리 정의된 특정 수식을 주어진 입력 값에 맞게 수행하였는지는 산출하되 중간 결과값을 보여주지 않고 증명할 수 있다. zk-SNARK is a concise zero-knowledge of statements with no interaction between prover and verifier,

When there is a relation of, the secret value needed to compute

Without revealing,

Algorithm to prove that you know. In other words, it is possible to prove whether a specific predefined formula is performed for a given input value, but without demonstrating the intermediate result value.

, 암호화된 투표 결과 값

및 상기 함수를 올바르게 수행하기 위해 필요한 비밀 값을 알고 있음을 증명하는 증명 값

이 출력된다. That is, if step 514, step 518, step 520 and step 526 are represented as a function as shown in Figure 6, the output number of the function as a serial number

Encrypted voting result

And a proof value that proves that the secret value needed to perform the function correctly is known.

Is output.

, 암호화된 투표 결과 값

및 증명 값

을 블록 체인에 기록한다. In step 530, the terminal device B 230 is a serial number

Encrypted voting result

And attestation values

Write to the blockchain.

Finally, steps 532 to 534 are steps corresponding to the "counting process". Hereinafter, a process performed for each step will be described in detail.

를 블록 체인에 기록한다. 이 때, 복호화 키는 암호화된 투표 결과 값을 복호화하는 키이다. In step 530, server 220 decrypts the decryption key.

Write to the blockchain. At this time, the decryption key is a key for decrypting the encrypted voting result value.

를 이용해 블록 체인에 기록된 모든 암호화된 투표 결과 값

을 복호화하여 개표를 수행한다. In step 532, the terminal device A 210 decrypts the decryption key recorded in the blockchain.

All encrypted voting result values recorded on the blockchain using

Decode and perform the counting.

In short, applying the zk-SNARK algorithm to electronic voting does not tell which voter voted which candidate, but can prove the final voting result. That is, the present invention can guarantee a secret ballot. In addition, the use of blockchain ensures the integrity of voting results and ensures fast counting results, just like traditional blockchain-based electronic voting.

In addition, embodiments of the present invention may be implemented in the form of program instructions that may be executed by various computer means to be recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Examples of program instructions such as magneto-optical, ROM, RAM, flash memory, etc. may be executed by a computer using an interpreter as well as machine code such as produced by a compiler. Contains high-level language codes. The hardware device described above may be configured to operate as one or more software modules to perform the operations of one embodiment of the present invention, and vice versa.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help the overall understanding of the present invention, the present invention is not limited to the above embodiments, Various modifications and variations are possible to those skilled in the art to which the present invention pertains. Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents and equivalents of the claims, as well as the appended claims, will belong to the scope of the present invention. .

Claims (9)

A terminal device provided in a polling place and performing electronic voting using a blockchain,
A memory unit for storing instructions readable by a computer; And
A processor unit implemented to execute the instruction,
The processor unit,
Voting result is encrypted by inputting a voter's secret key and a public random value for identifying a specific election, and a voting result corresponding to the voting right, and voting result value encrypted using the serial number with a public encryption key Calculate a value, calculate a proof value proving that the secret value is known without disclosing the secret value including the voter's secret key and the vote result value, the serial number, the encrypted vote result value, and And the proof value is recorded in the blockchain. The method of claim 1,
The public cryptographic key, the public random value, and the voter list are recorded in the blockchain, wherein the voter list includes voter information of each voter,
And the voter information corresponds to a hash value using the voter's secret key. The method of claim 2,
The public cryptographic key, the public random value and the voter list are calculated by a server of an election management committee and recorded in the blockchain,
And the voter information is calculated at the terminal device of the voter and transmitted to the server of the election management committee for registration. The method of claim 2,
And the processor unit determines whether voter information input by the voter and voter information recorded in the blockchain are the same. The method of claim 2,
And the processor unit verifies a signature value received from a server of the election administration committee using voter information input by the voter and a signature key received from a server of an election administration committee. In the server which is provided in the election management committee, and performs the electronic voting using the blockchain,
A memory unit for storing instructions readable by a computer; And
A processor unit implemented to execute the instruction,
The processor unit,
A public random value for identifying a specific election and a public encryption key for voting are generated, and a voter list is generated using voter information received from each of a plurality of voter terminal devices, and the voter list and the public random value are generated. And recording the public cryptographic key in the blockchain, and sending a signature key and a signature value of signing the voter information using the signature key to a terminal device provided in the polling place,
The terminal device provided in the polling station verifies the transmitted signature value by using voter information inputted by a voter and the transmitted signature key. The method of claim 6,
The processor unit writes a decryption key to the blockchain,
And said decryption key is a key for decrypting an encrypted voting result value which is calculated by a terminal apparatus provided in said polling station and recorded in said blockchain. In the electronic voting method performed in conjunction with the terminal device A of the voter, the terminal device B provided in the polling place and the server provided to the election management committee,
Generating, by the terminal device A, voter information corresponding to a secret key of a voter and transmitting the voter information to the server;
The server, recording on the blockchain a list of voters generated using the transmitted voter information, a public random value for identifying a specific election, and a public encryption key for voting;
The terminal device B calculates a serial number corresponding to the voting right by using the voter's secret key input from the voter and the shared random value recorded in the blockchain, and shares the voting result value performed using the serial number. Encrypting with an encryption key to produce an encrypted voting result value, calculating an authentication value proving that the secret value is known without disclosing a secret value including the voter's secret key and the voting result value, the serial number Recording the encrypted voting result value and the attestation value in a blockchain; And
Registering, by the server, in the blockchain a decryption key that decrypts the encrypted voting result value. A computer-readable recording medium having recorded thereon a program for performing the method of claim 8.

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