KR102144614B1 - 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 and a server for performing electronic voting based on a blockchain with guaranteed secret election, and an electronic voting method. The disclosed terminal device includes a memory unit for storing instructions readable by a computer; And a processor unit implemented to execute the command: wherein the processor unit calculates a serial number corresponding to a voting right by using the input voter's secret key and a common random value for identifying a specific election, and The voting result value performed using the number is encrypted with a public encryption key to calculate the encrypted voting result value, and the secret value including the voter's secret key and the voting result value is not disclosed using the zk-SNARK algorithm. A proof value proving that the secret value is known is calculated, and the serial number, the encrypted voting result value, and the proof value are recorded in the 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 block chain-based electronic voting method that ensures confidentiality while ensuring de-intermediation and non-forgery and alteration of the block chain, and a terminal device and a server performing the same.

Blockchain is an open common ledger management technology that distributes and stores data, and ensures the transparency of transactions. Several recent studies have focused on the de-intermediation and non-forgery of the blockchain, and are studying blockchain-based electronic voting, but applying general blockchain technology that provides transaction transparency to electronic voting that needs to ensure secret elections. It is not appropriate to do.

1 is a diagram showing the concept of a conventional blockchain-based online voting system supervised by the Central Election Commission.

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

First, the encrypted voting records recorded by voters on the blockchain are decrypted on the voting server and the counting server, and the servers of the elections commission are fully trusted. However, if the server is attacked, the possibility of forgery and alteration of the voting result exists.

Second, since the voting records listed on the blockchain are stored in the form of including the voter information, the voting server and the counting server capable of decrypting the encrypted voting record can sufficiently know the voter's vote results. This means that it is not possible to guarantee a completely secret election within an electronic voting, and if the server is attacked, there is a risk that the voting results of all voters may be revealed.

In order to solve the problems of the prior art as described above, in the present invention, a block chain-based electronic voting method that guarantees de-intermediation and non-forgery and alteration of the block chain while ensuring confidentiality, and a terminal device and a server performing the same I would like to suggest.

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

In order to achieve the above object, according to a preferred embodiment of the present invention, a terminal device provided at a polling place and performing electronic voting using a block chain, comprising: a memory unit for storing a computer-readable instruction; And a processor unit implemented to execute the command: wherein the processor unit calculates a serial number corresponding to a voting right by using the input voter's secret key and a common random value for identifying a specific election, and Encrypting the voting result value performed using the number with a public encryption key to calculate an encrypted voting result value, and knowing that the secret value is known without revealing the secret value including the voter's secret key and the voting result value. A terminal device is provided, characterized in that it calculates a proof value to prove, and records the serial number, the encrypted voting result value, and the proof value in the block chain.

The public encryption key, the public random value, and a voter list are recorded in the block chain, but the voter list includes voter information for each of the voters, and the voter information corresponds to a hash value using the secret key of the voter. I can.

The public encryption key, the public random value, and the voter list are calculated on the server of the election management committee and recorded in the block chain, and the voter information is calculated on the terminal device of the voter and then transmitted to the server of the election management committee. And can be registered.

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

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

In addition, according to another embodiment of the present invention, a server provided in the election management committee and performing electronic voting using a block chain, comprising: a memory unit storing instructions readable by a computer; And a processor unit embodied to execute the command, wherein the processor unit generates a common random value for identifying a specific election and a public encryption key for performing voting, and received from each of the terminal devices of a plurality of voters. A signature value obtained by creating a voter list using voter information, recording the voter list, the public random value, and the public encryption key in the blockchain, and signing the voter information using a signing key and the signing key A server provided by a server, characterized in that the transmitted signature value is verified using the voter information input by the voter and the transmitted signature key, wherein the terminal device provided at the polling place is transmitted to the terminal device provided at the polling place. do.

In addition, according to another embodiment of the present invention, in an electronic voting method performed in conjunction with a voter's terminal device A, a terminal device B provided in a polling place, and a server provided in the election management committee, the terminal device A, Generating voter information corresponding to the voter's secret key and transmitting it to the server; Recording, by the server, 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 performing a vote on a blockchain; The terminal device B calculates a serial number corresponding to a voting right using the voter's secret key input from the voter and a public random value recorded in the block chain, and shares the result value of the voting performed using the serial number. Calculate a voting result value encrypted by encryption with an encryption key, calculate a proof value proving that the secret value is known without disclosing the secret value including the secret key of the voter and the voting result value, and the serial number And recording the encrypted voting result value and the proof value in a block chain; And registering a decryption key for decrypting, by the server, the encrypted voting result value in the block chain.

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

In addition, the effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a diagram showing the concept of a conventional blockchain-based online voting system supervised by the Central Election Commission.
2 is a diagram showing a schematic configuration of an electronic voting system using a block chain 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 showing the concept of an electronic voting method according to an embodiment of the present invention.
5 is a diagram showing a flowchart of an electronic voting method according to an embodiment of the present invention.
6 is a diagram for explaining the concept of zk-SNARK according to the present invention.

Singular expressions used in the present specification include plural expressions unless the context clearly indicates otherwise. In the present specification, terms such as “consisting of” or “comprising” should not be construed as necessarily including all of the various elements or various steps described in the specification, and some of the elements or some steps It may not be included, or it should be interpreted that it may further include additional components or steps. In addition, terms such as "... unit" and "module" described in the specification mean units that process at least one function or operation, which may be implemented as hardware or software, or as 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 showing a schematic configuration of an electronic voting system using a block chain according to an embodiment of the present invention.

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

A plurality of terminal devices A 210 perform the process of registering voters and counting votes, and the server 220 is interlocked with a plurality of terminal devices A 210 and B 230, and initiates an election. And the terminal device B 230 performs a voting process.

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

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

The memory unit 320 may be a volatile and/or nonvolatile memory, and stores commands or data related to at least one other component of the terminal devices 210 and 230 or 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, and a communication processor. In particular, the processor unit 330 may execute a command related to execution of the computer program.

The display unit 340 may include 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 an electronic voting system will be described with reference to FIGS. 4 and 5.

4 is a diagram illustrating the concept of an electronic voting method according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating a flowchart of the electronic voting method according to FIG. 4.

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

First, steps 502 to 508 are steps corresponding to the "voter registration" process. Hereinafter, the process performed for each step will be described as follows.

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, the server 220 determines the voter's secret key.

Is transmitted to the terminal device A 210. That is, the voter enters his/her ID (for example, a resident registration number) into the server 220, and a secret key corresponding to the voter's ID in one-to-one

Is randomly selected and given. At this time, the server 220 is the transmitted secret key

Does not store and thus the secret key

Is information that only voters can 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 is a secret key

Use Voter Information

Yields At this time, voter information

Is information about a publicly disclosed voter.

This is information that corresponds to and one-to-one.

및 유권자 정보

가 산출될 수 있다. According to an embodiment of the present invention, a secret key is obtained 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. I.e. voter information

The voter's 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, the terminal device A (210) is the voter information

Is transmitted to the server 220. At this time, the server 220 is the 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, the server 220 determines the voter information

Records a list of voters that includes is on the blockchain. At this time, the blockchain can be accessed by all voters, and the voter list is the voter information for all voters.

Includes.

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

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, the server 220 uses the election paper data form, a public random value for identifying a specific election.

And public encryption key for voting

To the blockchain. In this case, 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, the server 220 determines the voter information

Signing key to perform signing on

Produces At this time, the signing key

The voter's secret key

If it is leaked, someone else's secret key

This is the key used to prevent voting rights.

Subsequently, steps 514 to 528 are steps corresponding to "voting voters" performed by the terminal device B 230 provided in the polling place. Hereinafter, the 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 the secret key of the voter inputted through a keyboard or the like.

And public random values recorded on the blockchain

Using the serial number corresponding to the voting right

Yields (

). That is, the serial number

Corresponds to the right to cast a vote.

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

Use to calculate the voting result value. And, in step 518, the terminal device B 230 is the public encryption key recorded in the block chain

Encrypted voting result value by encrypting the voting result value

Yields (

).

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 is the voter information input by the voter through a keyboard, etc.

And voter information recorded on the blockchain

Determine whether is the same (

). That is, step 518 is a step of proving that the voter himself 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, the server 220 records the voter information on the blockchain.

Signing key

Signed with the signature value

And, in step 524, the server 220 is the signing 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 is the voter information input by the voter.

And the signing key received from the server 220

The signature value received from the server 220 using

Verifies (

). If not verified, the voter must

It turns out that it is a person who performs voting by using and cannot perform voting.

, 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, the terminal device B 230 is the secret key of the voter

, Voting results and voter information

A proof value that proves that the secret value is known without disclosing the secret value containing

Yields Accordingly, secret voting can be carried out. In this case, a zk-SNARK (zero-knowledge Succinct Non-interactive Argument of Knowledge) algorithm may be used. This is 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 proof of a statement without interaction between the prover and verifier,

When there is a relational expression of, the secret value required to calculate the relational expression

Without revealing,

It is an algorithm that proves knowing. In other words, it is possible to prove whether or not a specific predefined formula was performed according to a given input value, but without showing an 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 one function as shown in FIG. 6, the serial number is the output value of the function.

, Encrypted voting result value

And a proof value proving that the secret value required to properly perform the function 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 value

And proof value

To the blockchain.

Finally, steps 532 to 534 are steps corresponding to the "counting process". Hereinafter, the 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, the server 220 decryption key

To the blockchain. In this case, 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 is the decryption key recorded in the block chain.

All encrypted voting result values recorded on the blockchain using

Is decoded and counted.

In short, applying the zk-SNARK algorithm to electronic voting, it is not possible to know which voter voted which candidate, but can prove the final voting result. That is, the present invention can guarantee secret voting. In addition, since blockchain is used, it is possible to guarantee the integrity of voting results and to ensure fast counting results, similar to existing blockchain-based electronic voting.

Further, embodiments of the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -Examples of program instructions such as magneto-optical, ROM, RAM, flash memory, etc., can be executed by a computer using an interpreter as well as machine code such as created by a compiler. Contains high-level language code. The above-described hardware device may be configured to operate as one or more software modules to perform the operation of the embodiments of the present invention, and vice versa.

As described above, in the present invention, specific matters such as specific components, etc., and limited embodiments and drawings have been described, but these are provided only to help the general understanding of the present invention, and the present invention is not limited to the above embodiments, Anyone of ordinary skill in the field to which the present invention pertains can make various modifications and variations from this description. Accordingly, the spirit of the present invention is limited to the described embodiments and should not be defined, and all things having equivalent or equivalent modifications to the claims as well as the claims to be described later fall within the scope of the spirit of the present invention. .

Claims (9)

In a terminal device provided at a polling place and performing electronic voting using a block chain,
A memory unit for storing a computer-readable instruction; And
Processor unit implemented to execute the command: including,
The processor unit,
An encrypted voting result by calculating a serial number corresponding to the voting right using the entered voter's secret key and a public random value for identifying a specific election, and encrypting the voting result value performed using the serial number with a public encryption key Calculate a value, calculate a proof value that proves that the secret value including the secret key of the voter and the voting result value is not disclosed, and the serial number, the encrypted voting result value, and And recording the proof value in the block chain. The method of claim 1,
The public encryption key, the public random value, and a voter list are recorded in the block chain, and the voter list includes voter information of each of all voters,
The terminal device, wherein the voter information corresponds to a hash value using the secret key of the voter. The method of claim 2,
The public encryption key, the public random value, and the voter list are calculated in the server of the election commission and recorded in the blockchain,
The terminal device, characterized in that the voter information is calculated by the terminal device of the voter and then transmitted to the server of the election management committee to be registered. The method of claim 2,
And the processor unit determines whether the voter information input by the voter and the voter information recorded in the block chain are the same. delete delete delete In the electronic voting method performed in conjunction with a voter's terminal device A, a terminal device B provided in a polling place, and a server provided in the election management committee,
Generating, by the terminal device A, voter information corresponding to a voter's secret key and transmitting it to the server;
Recording, by the server, 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 performing a vote on a blockchain;
The terminal device B calculates a serial number corresponding to a voting right using the voter's secret key input from the voter and a public random value recorded in the block chain, and shares the result value of the voting performed using the serial number. Calculate a voting result value encrypted by encryption with an encryption key, calculate a proof value proving that the secret value is known without disclosing the secret value including the secret key of the voter and the voting result value, and the serial number And recording the encrypted voting result value and the proof value in a block chain; And
And registering a decryption key for decrypting, by the server, the encrypted voting result value in the block chain. A computer-readable recording medium recording a program for performing the method of claim 8.

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