KR102525157B1 - Apparatus and Methods for Verifiable Lottery - Google Patents

Abstract

Disclosed is an apparatus and method for a verifiable lottery that solves a trust problem between a participant and an organizer by introducing a blockchain into a lottery system.

Description

Apparatus and Methods for Verifiable Lottery

The present invention solves the trust problem between a participant and an organizer in a lottery system by introducing a blockchain, and relates to a computer software apparatus and method for lottery.

Existing lottery programs are implemented along a centralized system and run on a single computer. The fairness of the lottery system is determined according to the irregularity of the random value used during lottery execution, and all information can be modified arbitrarily if all information is centralized and administrator has authority, which raises the reliability problem of the lottery system. Most of the technologies that ensure random value irregularity can be countered by using public random service beacons provided by NIST in the US, but the problem of relying entirely on a centralized server manager is still not solved. In order to solve the administrator's authority problem, it is necessary to devise a technique that allows anyone to verify the lottery results. That is, by constructing a lottery system that uses random values that are generated at the time everyone anticipates and agrees to while maintaining the irregularity of the random values, the fairness of the lottery system is supported and the lottery results can be verified.

Basically, in the Bitcoin blockchain, block miner nodes distributed around the world compete to solve a cryptographic hash puzzle, and through this, a chain between blocks is formed. The process of solving the cryptographic hash puzzle for the construction of such a block chain basically involves a process based on many irregularities, and is similar to the way that block miners generate a new random value each time they create a block. While utilizing these characteristics, a blockchain-based verifiable lottery system can be configured by configuring the lottery system operation itself as a program that runs on a blockchain called a smart contract.

The form of block chain is divided into public block chain, permissioned block chain, and consortium block chain. In the present invention, a specific type of block chain is not assumed, but for convenience of explanation, a permissioned block chain situation is assumed and described. do.

Hyperledger Fabric, an open source blockchain platform under the Linux foundation, uses a permissioned blockchain to enable transparent transactions between companies.

Existing centralized lottery systems have reliability problems, and these lottery systems have the following three major problems.

* Predictability

* Modifiability

* Information hiding

Predictability means that the winner can be predicted in advance, operability indicates that information related to the lottery can be modified arbitrarily, and confidentiality of information means that information related to the lottery is not disclosed to participants.

In order to solve this problem, the present invention devised a reliable lottery system device and method, and this invention supports the lottery system to have fairness, immutability, transparency, and verifiability properties, thereby It solves three main problems of the existing lottery system.

Fairness means that the winner cannot be predicted in advance, immutability means that the lottery information once recorded cannot be modified later, and transparency means that the lottery-related information must be disclosed to the participants. And verifiability means that it must be possible to verify that the lottery system satisfies the above properties.

Reflecting this, the present invention is to develop a reliable lottery program having fairness, immutability, transparency, and verifiable properties by implementing an existing centralized lottery program using a blockchain platform. More specifically, it is related to developing a reliable lottery program based on blockchain that provides lottery services.

The present invention proposes a reliable lottery device and method having fairness, immutability, transparency, and verifiable properties using a blockchain platform.

In the present invention, the random value used to realize fairness is divided into two types. It is a random value generated by a block hash of the future Bitcoin blockchain and a cryptographically secure pseudo random number generator. The winner is determined based on the combination of the two.

Transparency and immutability are realized by a distributed replicated ledger implemented as a blockchain. Transactions related to the lottery are recorded on distributed peer nodes to ensure transparency, and immutability is secured because they are stored in the form of a block chain.

The result verification of the lottery system proposed in the present invention is related to smart contracts executed by peer nodes operating in a distributed environment. The smart contract, which runs independently on each peer node, verifies the lottery result by recreating the verification key generated at the time the winner is determined and comparing it.

A smart contract is a program that performs input/output with a distributed replicated ledger. In the Hyperledger Fabric used in the present invention, this is also called a chain code.

It provides a technique for guaranteeing the anonymity of participants by identifying participants with the hash of the public key assigned by the CA.

The present invention solves the reliability problem by introducing a blockchain and proposing a decentralized lottery system instead of the existing centralized one.

It provides a web-based program that provides lottery-related services using Hyperledger Fabric, an open source blockchain platform under the Linux foundation.

The present invention can reduce social costs due to dishonest lottery events by presenting a reliable lottery system and introducing a block chain.

Techniques for making the existing centralized lottery system reliable have been proposed, but there are still problems such as a single point of failure, which make implementation complicated and difficult. However, by using a blockchain platform, the reliability problem can be easily solved and efficient implementation is possible.

1 is a diagram of the overall system structure proposed in the present invention.
Figure 2 is a conceptual diagram of state changes and available chain codes (smart contracts) of a lottery event in chronological order.
3 is a block diagram of a verification key derivation process used for verification.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. Like reference numerals have been used for like elements throughout the description of each figure.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The term “and/or” includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "comprise" or "having" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in the present application, they should not be interpreted in an ideal or excessively formal meaning. don't

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail. In order to facilitate overall understanding in the description of the present invention, the same reference numerals are used for the same components in the drawings, and redundant descriptions of the same components are omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is an overall system structure diagram proposed in the present invention.

In Figure 1, the blockchain network is implemented in the form of a Docker-based container and consists of two organizations and two peers for each organization. A peer executes a transaction in the form of a smart contract (chain code) and records the record on the blockchain. Chaincode is also implemented as an independent container and executed by peer nodes. The DB uses couchDB and serves to store and manage the block chain, which is a kind of distributed database. The orderer sets the order of transactions requested from the web server (SDK), forms blocks, and delivers them to peer nodes. CA (Certificate Authority) in Hyperledger Fabric manages the identity of the components that make up the blockchain network. And the identity of the participants for the lottery is also managed by the CA.

The web server and Hyperledger/Fabric Software development kit (SDK) perform interaction between the user (web client) and the blockchain network. That is, upon receiving a user's request, it is delivered to the constituent nodes of the blockchain network according to the implemented protocol and the result is notified to the user. It also plays a role in obtaining a target block number to be used as a random source from a Bitcoin-based random beacon.

Web clients and users are divided into participants and organizers according to actual users. The types of transactions they can perform are divided into five types as follows. A participant consists of a query transaction to retrieve a list of lottery events, a subscribe transaction to execute participation in a lottery event, a check transaction to check the lottery result (decision on the winner), and a verify transaction to verify the lottery. Organizers can register for lottery events through an open transaction. All of the above transactions are implemented in the form of a smart contract on a blockchain network.

The Bitcoin blockchain functions as a beacon that provides random numbers. Blocks in Bitcoin have a hash of each previous block, and the hash value is almost impossible to predict due to hash characteristics. Therefore, the algorithm for determining the winner uses the hashes of future blocks that have not yet been formed as a source of randomness.

Figure 2 is a conceptual diagram of state changes and available chain codes (smart contracts) of a lottery event in chronological order.

Figure 2 shows state changes and available chain code operations according to the chronological order of lottery events.

The lottery event is chronologically divided into an issue date, a due date, and an announcement date. The date of issue is the date on which the lottery event is triggered. Between the date of publication and the deadline, participants may participate in registered events. And you can check and verify the results after the announcement date. One of the chaincode operations, query, is omitted from the figure because it can be called at any time regardless of chronological order.

The open transaction registers the lottery event. As input, it receives the event name, issue date, deadline, announcement date, target block number, number of participating members, number of winners, random key, and member name, and registers the requested event in the lottery network. The target block number is selected by predicting a block number adjacent to the announcement date by calculating the recent block creation rate of the Bitcoin blockchain. The random key provides a unique number to distinguish each event.

The subscribe transaction adds the participant to the list of participants for the selected raffle event. The subscribe transaction also registers registered participants in the CA's database and receives a public key from the CA before invoking the associated chaincode. Then, participants are identified through hash values of public keys. Due to the one-way nature of the hash function, inverse transformation is impossible, so anonymity is guaranteed, and if the result is obtained, the winner can safely prove that they have won.

The check transaction can be called when the current time is the announcement date, and calls the chaincode that determines the winner. When the check transaction is called, the target block to be used as a random source must be issued. otherwise it fails. If the target block has been issued, the hash value of the block is read and the winner determination algorithm using the random source is called. The winner determination algorithm operates in a deterministic manner once the random source is determined. In this implementation, the winner is determined as follows.

1. Assign a random hash value (X _i ) to each integer belonging to [0, 1, ..., number of participants - 1]. In a (key, value) pair, the key corresponds to an integer and the value corresponds to a hash.

2. X _i of 1 is calculated as: Let Y be the value calculated using the random key and target block hash assigned at the time of registering the lottery event as the key and data of each SHA256-HMAC. The hash value calculated by using the value obtained by concatenating the index (i) of an integer value at the end of the value converted to a string of Y as the input of SHA256 is assigned to X _i .

3. Sort by assigned (hash) value. And store the result in an array.

4. Determine the ranking of the winner by the index sequence number of the array. For example, if the number of winners is 2, the first index number becomes 1st place, and the second index number becomes 2nd place.

5. Participants will be assigned numbers in the order in which they initially entered.

When the winner is determined in the above way, the smart contract records the winner in the winner field of the lottery event.

The check transaction also generates a verification key for later verification.

3 is a block diagram of a verification key derivation process used for verification.

Referring to FIG. 3, for the integrity of the random source and lottery information, the hash value of the target block and the previous three blocks, the random key provided at the time of lottery registration, the HMAC function, and the lottery information are connected to the hash value created by the SHA256 function. Generates a hash of the concatenated values. And the verification key (VerifiableRandomKey) generated in this way is recorded in the verification key field of the lottery information and used by the verify transaction.

The verify transaction verifies whether the winners match by recreating the integrity of the recorded lottery information and the lottery results.

A verification key is generated according to the verification key derivation process of FIG. 3 and the verification key recorded in the check transaction is compared.

The verification key is finally constructed by concatenating the resulting string of HMAC and SHA256. The initial random key is used as the HMAC key, the hash function is SHA256, and the data to be used as a message can be the target block and the previous three hashes. The contents belonging to Lottery information include the name of the lottery event, the random key used when registering for the event, the issue date, the deadline date, the registration date, the number of winners, the list of winners, the number of participants, the list of participants, the target block number, and the source code of the winner determination algorithm. .

The operation of the method according to the embodiment of the present invention can be implemented as a computer readable program or code on a computer readable recording medium. A computer-readable recording medium includes all types of recording devices in which data that can be read by a computer system is stored. In addition, computer-readable recording media may be distributed to computer systems connected through a network to store and execute computer-readable programs or codes in a distributed manner.

In addition, the computer-readable recording medium may include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, and flash memory. The program command may include high-level language codes that can be executed by a computer using an interpreter or the like as well as machine code generated by a compiler.

Although some aspects of the present invention have been described in the context of an apparatus, it may also represent a description according to a corresponding method, where a block or apparatus corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may also be represented by a corresponding block or item or a corresponding feature of a device. Some or all of the method steps may be performed by (or using) a hardware device such as, for example, a microprocessor, programmable computer, or electronic circuitry. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

In embodiments, a programmable logic device (eg, a field programmable gate array) may be used to perform some or all of the functions of the methods described herein. In embodiments, a field programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described herein. Generally, methods are preferably performed by some hardware device.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the present invention described in the claims below. You will understand that you can.

Claims (18)

A method for performing a verifiable lottery between participants and organizers by the operation of a smart contract in a blockchain network,
Registering lottery information of a lottery event input from an organizer on a lottery network by calling the smart contract by an open transaction executed by the blockchain network;
Adding a participant to a participant list of the lottery event by calling the smart contract by a Subscribe transaction executed by the blockchain network;
Winners and winning results by a winner determination algorithm that uses the hash value of a pre-issued target block as a random source when the current time reaches the announcement date by calling the smart contract by the Check transaction executed by the blockchain network deriving;
recording the winner in a winner field of the lottery event by the Check transaction executed by the blockchain network;
generating a first verification key for verifying integrity of the lottery information by the check transaction executed by the blockchain network; and
The smart contract is called by the Verify transaction executed by the blockchain network to generate a second verification key using the lottery information registered on the lottery network, and the second verification key is used to generate the first verification key. and verifying the integrity of the winning result by comparing it with a key. The method of claim 1,
In the step of registering the lottery information of the lottery event on the lottery network,
Registering the lottery information of at least one of the name of the lottery event, the issue date, the deadline, the announcement date, the target block number, the number of participants, the number of winners, a random key, and a participant name on the lottery network,
The target block number is a prediction of the target block number adjacent to the announcement date by calculating the block generation speed of the Bitcoin block chain,
wherein the random key is for distinguishing at least one lottery event. The method of claim 1,
The step of adding to the list of participants of the lottery event,
registering participants registered on the lottery network in a CA database;
receiving a public key from the CA database; and
A method for a verifiable lottery, comprising identifying and distinguishing the identities of the participants through a hash value according to the public key. delete The method of claim 1,
The winner determination algorithm,
A random hash value is assigned to each integer individually given to the participant,
A method for a verifiable lottery, wherein the integers are rearranged based on the random hash value, and a winner is determined according to the rearranged order. The method of claim 5,
The random hash value,
A temporary value is calculated using the random key and the hash value of the target block as the key and data of SHA256-HMAC,
A method for a verifiable lottery, which is a hash value calculated by converting the temporary value into a string and using a value obtained by combining an integer index at the end of the string as an input of SHA256. The method of claim 1,
The first verification key,
The method for a verifiable lottery, which is generated by combining the hash value of the target block and the blocks immediately preceding the target block, the random key with the HMAC function, and the lottery information with the SHA256 function. The method of claim 7,
The second verification key,
A method for a verifiable lottery that is calculated identically to the first verification key based on the lottery information registered on the lottery network. The method of claim 1,
The method for a verifiable lottery, wherein the blockchain network is a permissioned blockchain. A device for performing a verifiable lottery between participants and organizers by the operation of a smart contract in a blockchain network,
a memory for storing at least one transaction command calling the smart contract; and
A processor executing at least one transaction instruction stored in the memory;
The at least one transaction command,
A command to register the lottery information of the lottery event entered from the organizer on the lottery network;
instructions to add a participant to a list of participants in said drawing event;
When the current time reaches the announcement date, a command to derive a winner and a winning result by executing a winner determination algorithm using the hash value of a pre-issued target block as a random source;
instructions to record the winner in a winner field of the lottery event;
A command to generate a first verification key for verifying the integrity of the lottery information, and
And verifying the integrity of the winning result by generating a second verification key using the lottery information registered on the lottery network and comparing the second verification key with the first verification key. device for possible lottery. The method of claim 10,
In the command to register the lottery information of the lottery event on the lottery network,
Registering the lottery information of at least one of the name of the lottery event, the issue date, the deadline, the announcement date, the target block number, the number of participants, the number of winners, a random key, and a participant name on the lottery network,
The target block number is a prediction of the target block number adjacent to the announcement date by calculating the block generation speed of the Bitcoin block chain,
wherein the random key is for distinguishing at least one lottery event. The method of claim 10,
The command to add to the list of participants of the lottery event,
instructions for registering participants registered on the lottery network in a CA database;
A command to assign a public key from the CA database; and
An apparatus for verifying a lottery, comprising a command for identifying and distinguishing the identities of the participants through a hash value according to the public key. delete The method of claim 10,
The winner determination algorithm,
A random hash value is assigned to each integer individually given to the participant,
An apparatus for a verifiable lottery, wherein the integers are rearranged based on the random hash value, and a winner is determined according to the rearranged order. The method of claim 14,
The random hash value,
A temporary value is calculated using the random key and the hash value of the target block as the key and data of SHA256-HMAC,
Apparatus for verifiable lottery, which is a hash value calculated by converting the temporary value into a string and then using a value obtained by combining an integer index at the end of the string as an input of SHA256. The method of claim 10,
The first verification key,
Apparatus for a verifiable lottery, which is generated by combining the hash value of the target block and the blocks immediately preceding the target block, the random key with the HMAC function, and the lottery information with the SHA256 function. The method of claim 16
The second verification key,
An apparatus for a verifiable lottery that is calculated identically to the first verification key based on the lottery information registered on the lottery network. The method of claim 10,
The blockchain network is a permissioned blockchain, a device for a verifiable lottery.

Images