WO2020138733A1

WO2020138733A1 - Blockchain system for providing anonymity of private information and method for providing anonymity of private information in blockchain

Info

Publication number: WO2020138733A1
Application number: PCT/KR2019/016472
Authority: WO
Inventors: 김호원; 김명길; 박찬희
Original assignee: 부산대학교 산학협력단
Priority date: 2018-12-27
Filing date: 2019-11-27
Publication date: 2020-07-02
Also published as: KR20200081101A

Abstract

The present invention relates to a signature and verification technology for protecting private information included in a transaction on a blockchain platform, the technology comprising: an authentication module for generating a first certificate; a node for generating a second certificate in which private information is omitted by using the first certificate generated in the authentication module and to which zero-knowledge is applied, and a transaction including the second certificate; and a verification module for verifying the transaction generated in the node.

Description

Blockchain system that provides anonymity of personal information and how to provide anonymity of personal information on blockchain

The present invention relates to a blockchain system that provides anonymity of personal information and a method of providing anonymity of personal information on a blockchain, and more specifically, a signature for protecting personal information included in a transaction on a blockchain platform. And verification technology.

Blockchain is a concept that was put to practical use in Bitcoin, which appeared in 2009, and is a database technology that stores data while preventing hacking through a shared ledger on a P2P network.

Later, as Ethereum proposed the concept of existing digital commands, smart contracts, and DApps that provide services based on these, blockchain technology began to expand into the platform area.

Many blockchain platforms do not have a separate device to safely manage sensitive data such as private information. Due to the technical characteristics of the distributed ledger, transactions stored on the blockchain are shared with all network participants. Therefore, when the blockchain technology is applied to an environment such as the Internet of Things, the anonymity of personal information of the IoT device is not guaranteed.

The authentication method for the existing user is mainly used by a third-party authentication authority and an X.509-based authentication method. In the case of a third-party certification authority, the attributes necessary for verification must be explicitly set, and there is a disadvantage that it causes a bottleneck for the system. In the case of X.509-based certificates, the authentication process is performed without the aid of a Certificate Authority, but there is a problem in that the entire signed attributes must be disclosed according to another Verifier request. .

The present invention is to solve the above problems, and an object of the present invention is to provide a signature and verification technology for protecting personal information included in a transaction in a blockchain platform.

The present invention is a block that provides anonymity of personal information to protect the personal information of a node by providing anonymity using a Zero-Knowledge-based certificate on a permissioned blockchain network. The purpose is to provide a method for providing anonymity of personal information in the chain system and blockchain.

The present invention provides anonymity of personal information to enable efficient network configuration by resolving the system bottleneck of the authentication module generated in the authentication process by dividing the protocol for generating, issuing, signing, revoking, and verifying certificates to each participating node. The purpose is to provide a blockchain system and a method for providing anonymity of personal information in the blockchain.

A blockchain system that provides anonymity of personal information according to the present invention for achieving the above object includes an authentication module for generating a first certificate; A node generating a second certificate to which personal information is omitted and zero-knowledge applied and a transaction including the second certificate using the first certificate generated by the authentication module; And it characterized in that it comprises a verification module for verifying the transaction generated at the node.

In addition, the authentication module is characterized in that by generating a public key and an authentication secret key using a random digital signature (Randomizable Digital Signature), and generating the first certificate by signing with the authentication secret key using a BBS signature protocol can do.

In addition, the node may be characterized by generating a second certificate to which zero knowledge is applied using the BBS signature protocol.

In addition, it may be characterized in that it further comprises an audit module for tracking the transaction using the public key for audit and the secret key for audit.

In addition, it may be characterized in that it further comprises a discarding module that discards the second certificate that needs to be discarded and transmits the fact of discarding the second certificate to the node.

On the other hand, a method for providing anonymity of personal information in the blockchain according to the present invention for achieving the above object comprises: (A) generating a first certificate by the authentication module; (B) the node using the first certificate, personal information is omitted, and zero-knowledge (Zero-Knowledge) is applied to the second certificate and the second certificate generating a transaction that includes; And (C) verifying the transaction by the verification module.

In addition, the (A) step, using a random digital signature (Randomizable Digital Signature) generating an authentication public key and an authentication secret key; And generating the first certificate by signing with the authentication secret key using the BBS signing protocol.

In addition, step (B) may be characterized in that a BBS signature protocol is used when generating the second certificate.

According to a blockchain system for providing anonymity of personal information according to an embodiment of the present invention and a method for providing anonymity of personal information in a blockchain,

First, if anonymity is provided using a Zero-Knowledge-based certificate on a Permissioned Blockchain network, the node's personal information can be protected.

Second, by dividing the certificate creation, issuance, signature generation, revocation, and verification protocols to each participating node, the system bottleneck of the authentication module generated in the authentication process is resolved, thereby enabling efficient network configuration.

1 is a view showing the structure of a blockchain block.

2 is a diagram showing a block structure of Hyperledger-Fabric.

3 is a block diagram of a blockchain system that provides anonymity of personal information according to an embodiment of the present invention.

4 is a diagram showing the process of issuing a zero-knowledge certificate and generating a transaction between an authentication module and a node.

5 is a diagram more specifically illustrating a process of generating a transaction providing anonymity using a zero-knowledge certificate.

6 is a diagram illustrating a process in which the audit module tracks a transaction.

7 is a view showing the relationship between the authentication module, the revocation module, and the node revoking the certificate.

8 is a flow chart showing the operation protocol of another embodiment applied to the blockchain.

9 is a flowchart of a method for providing anonymity of personal information in a blockchain according to an embodiment of the present invention.

10 is a diagram showing source code (a) for generating a certificate for which all attributes are not disclosed and source code (b) for verifying the generated certificate.

FIG. 11 is a view showing a result of verifying a certificate generated from the source code of FIG. 10(a).

12 is a graph showing the time required to generate and verify a certificate.

FIG. 13 is a view showing a result of verifying the source code (a) generating a certificate that only the ProofOfAge is published among the attributes and the generated certificate.

Hereinafter, a preferred embodiment of a blockchain system providing anonymity of personal information and a method of providing anonymity of personal information in a blockchain will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a block of a blockchain is a unit that provides final data, and is composed of a header and a body. Of the blocks, only blocks that are approved through the validation and consensus algorithm are registered on the blockchain. The data structure defined for each blockchain platform is different, but in general, the block header includes information about the block, such as the hash value of the previous block, the Merkle Root Hash (MRH) value, and information necessary for verification, and Contains necessary information for the network. The block body contains transactions.

Blockchain is a technology that allows network participants to store the block containing the transaction in a distributed data storage environment in the form of a chain created by P2P method, and is a database technology that provides immortality that is impossible to tamper with. As the concept of logic level smart contracts and application level DApps are included in the blockchain, it has developed into a platform area technology that enables service development, distribution, and management in addition to database functions.

Blockchain structure can be divided into Permissioned and Permissionless.

The permission structure is a public structure blockchain that anyone can freely participate in the network. It is a completely decentralized structure where non-validated nodes can participate in transaction creation, verification, and consensus algorithms to store data on the blockchain. In order for the blockchain network to be activated, it must be a structure that voluntarily participates in the network's consensus algorithm. In general, it uses a consensus algorithm based on PoW (Proof of Work) and PoS (Proof of Stake) as a method of maintaining the block generation time algorithmically in the network itself for network reliability while providing tokens such as cryptocurrency. do. Bitcoin and Ethereum are examples.

The non-permission structure is a blockchain of a consortium structure or a private structure, where only limitedly verified nodes verify transaction validity and perform consensus algorithms. In the case of a consortium structure, the verified nodes perform consensus algorithms at equal positions. In the case of a private structure, a single enterprise (Enterprise) takes care of everything. In the private structure, since the number of nodes participating in the consensus algorithm is small and only verified nodes can participate, the transaction processing speed is superior to the public structure. Representative examples include R3 Corda and Hyperledger-Fabric.

The consensus algorithm is the process of consensus who will have authority over the block in the shared ledger to store transaction data on the blockchain. The peer selected by the consensus algorithm registers the block it creates in its ledger and propagates it to other peers. Peers that have received the new block perform validation on the block and, if valid, reflect it in the ledger. Typical consensus algorithms include Proof of Work (PoW), Proof of Stake (PoS), Delegated Proof of Stake (DPoS), and Practical Byzantine Fault Tolerance (PBFT).

Smart contract is a concept proposed by Nick Szabo in 1994. It is written in digital commands, and can execute contract contents according to conditions. This has a limitation that although the contract result according to the conditions is clear, it can be manipulated due to the nature of digital commands. However, as the result of the smart contract operation is reflected in the blockchain as it is fused with the blockchain, it becomes impossible to operate, and thus it has become a core technology of the blockchain. The smart contract serves as a logic layer of the platform that provides blockchain-based services in that it provides Turing completeness while performing contract contents according to conditions and can perform processes based on blockchain. .

DApp is a blockchain-based decentralized application. The resources used for the service are distributed and stored in the blockchain network, and in the case of highly reliable data registered in the blockchain, forgery and alteration is impossible once stored. The DApp service performs a process on the blockchain through a smart contract, and provides services by combining multiple smart contract functions. The service response time, which is the most important element of the application, is affected by the transaction processing speed of the blockchain network, so it is necessary to select the appropriate blockchain network structure according to the application needs.

In order to develop a DApp service, an interface for calling a smart contract from an application is required. Blockchain platforms, including the concept of smart contracts, support tools that support interworking interfaces.

Hyperledger is a project aimed at implementing standard blockchain technology supported by the Linux Foundation. Among them, Fabric is an enterprise blockchain framework, and is a blockchain platform with permission structure based on membership service. It is possible to write smart contracts based on go and java languages called chaincode, and there are several components in the network, including peers, orderers, and MSPs (Membership Service Providers).

Referring to FIG. 2, a block includes a header, data, and metadata.

Header has three variables in total. It is the Number variable that stores the index of the block, the PreviousHash variable that is the hash value of the previous block header, and the DataHash variable that is the Merkle Root Hash (MRH) value for data (transactions).

Data consists simply of an array of transactions, and each transaction is Type, Version, Timestamp, Channel ID, TxID, Epoch, Chaincode info, Creator Identity, Endorser Identity, Status, Read Set, Write Set, Key value, etc. It consists of.

Metadata consists of orderer identity, creator identity, and flag information for each transaction.

Peers are essential elements of the blockchain network, and are classified into Endorser and Comitter according to the role of Peer in Hyperledger-Fabric.

Endorser is a concept that includes a committer, and additionally performs an endorse function from the client's request. It executes the chaincode requested from the user (User, node), and goes through an endorsement process of signing the resulting state with the endorser's private key. It performs the function of returning the endorsement, which is the result of the subsequent process, to the user.

The Committer has a Ledger and an Event-hub. Ledger is a shared ledger consisting of a blockchain and a local database, and Event-hub is an interface used to request functions from a committer and receive a response. After the function (read) that returns the contents of the ledger to the client by the query command requested from the client, and after validating the block received from the orderer It performs the function of saving in the Ledger.

In Hyperledger-Fabric, Ledger consists of an existing blockchain and a state database that tracks and stores the state of the blockchain. As with existing blockchains, Ledger provides immortality that cannot be forged and contains information about transactions and networks. The State Database is a LevelDB-based database composed of key-value-based pairs, and has the function of recording and tracking the latest state stored in the blockchain. This reduces the time to search for state information in the blockchain by not searching the entire blockchain to know the current state of the ledger.

The orderer receives the endorsement from the client and performs a function for storing it in the blockchain. First, since the header information of the next block varies according to the order of the transaction, the blockchain organizes the order of the endorsement to perform registration. Thereafter, a packaging process is performed to convert to a block form for storage in a blockchain. In order to reflect the last created block in the Ledger of the corresponding channel, it plays a role of delivering the generated block to Peers (transferor, committer) with the Ledger. The orderer that performs the above functions is an essential element of the channel of the Hyperledger-Fabric network, and multiple orderers can exist in one channel. Orderers) decide the creation authority for the block through the consensus process.

Membership Service Provider (MSP) is a key element in controlling access authority in a Hyperledger-Fabric network. It is conceptually divided into 4 types according to required roles such as network, channel, peer, and orderer, and provides access control function through certificate-based authority. The network MSP controls the authority to perform network management (channel creation, etc.). The channel MSP controls authority for peers in a channel. The peer MSP controls the authority for the peer in the same way as the channel MSP, but is applied only to the peer. The orderer MSP controls the authority for the orderer.

Fabric-CA is an element that plays the role of a certification authority in a Hyperledger-Fabric network and can be used selectively. It works in conjunction with MSP to issue and manage certificates requested by peers, and provides two types of certificates. Ecert (Enrollment Certificate) is an identifier of a peer, and is used continuously. Tcert (Transaction Certificate) is used for transaction verification and is disposable.

Channel is a basic network unit of Hyperledger-Fabric, and each channel has an independent blockchain shared ledger and chaincode. Channel creation is possible only for users with authority to the system in the network MSP, and basically consists of an organization including a peer, an orderer, and an MSP. That is, each channel is a sub-network having a file system independent of the other channels in one entire network.

The chaincode of Hyperledger-Fabric is a smart contract concept based on go and java languages. However, unlike Ethereum's smart contract, where binary source code is registered on the blockchain, verified peers registered on the blockchain network have a chaincode. Chaincode is divided into system chaincode and general chaincode. The system chaincode is a chaincode that performs the 　network system process and can be registered when the network is created, and cannot be changed after the network is activated. The general chaincode is a chaincode that provides services, and is performed in the form of a transaction through an endorser at the request of users. It is possible to create, modify, etc., and is maintained in a channel unit. The result of executing the general chaincode is a transaction. The chaincode proposed by the client is executed and verified (signed) by the endorser, and transmitted to the client in the form of an endorsement. Then, the client checks the endorsement policy, which is the execution condition of the transaction, and sends it to the orderer. Transactions that are the result of the transmitted chaincode go through the ordering and packaging process by the orderer, and the generated blocks are sent to the endorser and committer for validation. ) After performing the process, it is reflected in the Ledger.

The consensus algorithm in Hyperledger-Fabric refers to the process of endorsement, ordering and validation for a transaction. That is, the transaction requested from the client is verified by the peer, and through the ordering and packaging process by the orderer who creates the block through the consensus process, it is stored in the ledger. Refers to the overall transaction execution process for performing validation. The endorsement is the result of the peer executing, verifying and signing the requested transaction.

Ordering is the process of deciding the order to register approved transactions received from multiple clients in a block (consensus algorithm applied).

Validation is a process performed by a peer with a ledger, and is a process of validating a block received from an orderer.

Fabric-SDK is a tool supported by Hyperledger-Fabric, and provides an interface that connects DApp and Chaincode to provide blockchain services. It supports go, node.js, and java languages. Services such as the ability to obtain access to an application through MSP, and the ability to propose a transaction (Chaincode) are available.

Hyperledger-Fabric's DApp operation process and blockchain interworking structure are similar to existing blockchain platforms. It uses HTTP-based protocol, and develops and distributes services in DApp based on the functions provided by Chaincode through SDK tools.

Zero-Knowledge is a protocol that guarantees anonymity, and it is a way to prove that a certifier has confidential information even if it does not disclose its own confidential information. That is, it is possible to perform validation of the user's personal information even if the user's personal information is not disclosed. The following three basic conditions must be met for zero knowledge. Completeness means that if a sentence is true, an honest Certifier must be able to convince the honest Verifier. Stability should not convince any honest Certifier that this sentence is true if any sentence is false. Zero-knowledge means that if a sentence is true, the Verifier must know nothing other than the true/false of the sentence.

Unlike the existing system that transmits a hash value of user authentication information, zero knowledge can prove that the information is correct without including the user authentication information on the network communication.

There are two signature protocols that provide anonymity based knowledge: CL (Camenish-Lysyanskaya) signature and BBS (Boneh-Boyen-Shacham) signature. Both are techniques using bilinear groups. The above signatures can prove that the user has a secret key by not providing a message signed with the secret key, but by providing the calculated value required by the verifier.

The CL (Camenish-Lysyanskaya) signature was proposed based on the initial Strong Diffie-Hellman (SDH). It has since been improved in terms of efficiency and is now based on the LRSW (Lysyanskaya-Rivest-Sahai- Wolf) assumption. Unlike the SDH assumption, LRSW supports independent discrete-logarithm according to the attributes of the message, which makes it more flexible. The CL signature can prove that the user has the secret key by providing the calculated value required by the verifier without going through the authentication process in which the user sends the message signed with the secret key.

The BBS (Boneh-Boyen-Shacham) signature is a proposed signature technique based on a new assumption of Declination LINear (DLIN). This is a zero-knowledge-based signature technique that is identical to the CL signature, providing anonymity. The Proof of Knowledge protocol, which verifies the presence or absence of information, has a more efficient feature than CL signature.

Randomizable digital signature is a signature technique that always consists of two elements regardless of the number of messages. Unlike digital signatures, random digital signatures must use the type-3 pairing method of bilinear groups unconditionally. However, several protocols based on CL signatures are more efficient while providing the same security and features as CL signatures, because they use type-3 pairing of bilinear groups for efficiency and security reasons.

The randomizable digital signature is a method of creating a new signature using an existing signature rather than creating a new signature according to each message m in the CL signature. Signature for message m

When present, random

Select a value,

By calculating, we create a new signature to provide randomness.

The blockchain system 100 that provides anonymity of personal information according to an embodiment of the present invention is a technology for a blockchain platform capable of providing anonymity. This embodiment provides anonymity for transactions containing personal information on a permissioned blockchain platform.

This embodiment proposes a method of applying a zero-knowledge-based signature technique to solve the anonymity problem of the blockchain network. For efficient processing of transaction generation, a key generation protocol of randomizable digital signature is used, and a protocol of BBS signature is applied to Proof of Knowledge.

This embodiment is connected to the blockchain network and performs functions such as creating, signing, issuing, revoking, tracking, etc., which contain the personal information of the node 110, and Attributes, which are personal information in the certificate. ).

Referring to FIG. 3, this embodiment includes an authentication module 120 for generating a first certificate; A node 110 for generating a transaction including a second certificate and a second certificate to which personal information is omitted and zero-knowledge is applied using the first certificate generated by the authentication module 120; It includes a verification module 140 for verifying the transaction generated by the node 110.

The certification module (Certificate Authority, 120) is a verified object that issues a certificate. Generate a public key and an authentication secret key based on a randomizable digital signature and use this to issue a certificate. The issued certificate has a flexible feature by applying the concept of zero knowledge.

The node 110 is a participating node 110 of the blockchain that receives a certificate and provides its own attribute through it. Based on the issued certificate, a BBS (Boneh-Boyen-Shacham) signature-based signature is generated, and a transaction including only information on some attributes is generated.

The node 110 may be implemented in various ways. If this embodiment is applied to the Internet of Things (IoT) environment, the node 110 may be an individual IoT sensor device.

The verification module (Verifier, 140) verifies the certificate of the node 110 using the public key of the authentication module (120).

The revocation authority (180) is a component that performs revocation of a certificate. A request for disposal is performed, and a process of passing the results to the node 110 and the verification module 140 is performed. As another embodiment, the authentication module 120 may perform this role in addition to issuing a certificate.

Referring to FIG. 4, the following structure is defined to provide anonymity to ensure that the transaction creator has the information without disclosing the private information of the transaction creator in the blockchain platform.

In order to increase efficiency, the authentication module 120 uses a randomizable digital signature when generating the authentication public key and the authentication secret key.

Node 110 generates a first public key and a first secret key using a random digital signature.

The authentication module 120 generates a first certificate by signing with an authentication secret key using the BBS signature protocol. The node 110 uses the first certificate together to generate a first public key.

The node 110 generates a second certificate in which part or all of personal information is omitted when creating a transaction. The second certificate is generated by applying zero knowledge using the BBS signature protocol. The node 110 generates a second public key and a second secret key to generate a second certificate. Other nodes can confirm the contents of the second certificate using the second public key.

Each transaction contains the certificate of the creator (node). Certificates created based on a zero-knowledged signature technique can provide anonymity to personal information even when included in a transaction.

5 shows a process of creating and verifying a transaction. In the first certificate issued by the authentication module 120, all of the personal information of the node 110 is contained in attributes.

When creating a transaction, the transaction must include a certificate of the node 110. However, when the first certificate is included in the transaction, there is a problem that all attributes are disclosed.

Accordingly, a new signature, that is, a second certificate is generated and provided to the verification module 140 so that the verification module 140 can check only the attributes that are selectively disclosed.

Since the second certificate provided to the verification module 140 includes only personal information permitted by the node 110 to be disclosed, personal information is not exposed during verification.

The verification module 140 verifies the second certificate included in the transaction using the authentication public key generated by the authentication module 120.

Figure 6 shows the audit (Auditor (Inspector)) process. The structure of FIG. 5 may acquire personal information of the node 110 by tracing each distributed transaction and collecting attribute information.

In order to prevent such a problem, an audit module 160 that performs a tracking function for a transaction may be additionally configured. The audit module 160 is a verified object with read permission for transactions within the blockchain network. The audit module 160 has a public key for auditing and a secret key for auditing to perform transaction tracking authority. The audit module 160 may be selectively used by configuring it as a participating node 110 of the blockchain network. The key generated by the audit module 160 may be applied with an existing asymmetric key encryption technique, to which the zero-knowledge concept is not applied.

7 shows a revocation process. When the attribute of a certificate is changed or a certificate containing the entire attribute is leaked, a process of revoking the certificate is no longer required.

For the revocation process, the revocation module 180 first generates a public key and a secret key to prove that the object has revocation authority. Subsequently, the node 110 that needs to discard the certificate transmits a request for revocation to the revocation module 180. The revocation module 180 checks whether the corresponding node 110 is authorized, and notifies the nodes 110 connected to the network that the certificate of the corresponding node 110 is revoked using its key signature.

The certificate revocation request is only possible for the authentication module 120, revocation module 180, and node 110 of the corresponding certificate. The verification module 140 does not have permission to request revocation.

In order to apply the blockchain platform, it is necessary to design a suitable blockchain structure for this embodiment. In particular, an object that manages a certificate and a key for the node 110 that generates a transaction is needed for interworking with the cryptographic library module.

The peer of this embodiment is a function that requests the authentication module 120 to register (or revoke) a certificate, and a block that requests the authentication service providing module 122 for signing and verifying a transaction It is the participating node 110 of the chain.

The authentication module 120 is an object that performs the same function as the authentication module 120 of the above-described embodiment.

The certification service provider module 122 transmits the signature and verification request received from the peer to the encryption unit. The authentication service providing module 122 simultaneously functions as a verification module 140 and a signer.

Crypto Library Module (124) is a library module that provides functions for key generation, signing, issuing, proof, revocation, tracking, etc. based on Zero-Knowledge.

The operation protocol from the application stage of the blockchain platform to the provision of anonymity will be described with reference to the drawings.

First, a blockchain network in which the peer and the authentication module 120 and the authentication service providing module 122 participate as a node 110 is built.

When building a blockchain network, it generates a zero-knowledge based authentication key (public key, secret key) used by the authentication module 120.

Subsequently, the peer requests registration with the authentication module 120. The authentication module 120 generates and registers a certificate of the peer based on the generated authentication key.

The blockchain network performs functions for transactions. The peer requests transaction signature or verification from the authentication service providing module 122. The authentication service providing module 122 performs signature or verification using the peer's certificate.

Next, a method for providing anonymity of personal information in a blockchain according to an embodiment of the present invention will be described.

Referring to FIG. 9, in this embodiment, the authentication module 120 generates a first certificate (S120 ), and the node 110 uses the first certificate to omit personal information and zero-knowledge And generating a transaction including the applied second certificate and the second certificate (S140), and the verification module 140 verifying the transaction (S160).

In step S120, in detail, generating an authentication public key and an authentication secret key using a randomizable digital signature (S122) and generating a first certificate by signing with an authentication secret key using the BBS signing protocol. It may include (S124).

Step S140 uses the BBS signature protocol when generating the second certificate.

Next, using the embodiment of the present invention, the actual blockchain system 100 was built, and it was confirmed whether normal operation is possible while maintaining anonymity.

Experiment.

The source code of FIG. 10( a) performs a function of generating a new signature (certificate) in which all attributes are not disclosed. FIG. 10(b) confirms whether the Proof of Knowledge protocol works by performing verification on the generated signature.

FIG. 11 is a result of verifying the certificate generated from the source code of FIG. 10(a). As shown, it was found that the information of uID, Name, Birthday, City, Country, and ProofOfAge included in the Attributes is not displayed in the certificate.

Signature generation is performed whenever node 110 generates a transaction. This is closely related to the transaction bottleneck. Referring to FIG. 12, the creation and verification of one new signature consumes an additional time cost of about 92.77 ms. The signature generation process and the verification process have a disadvantage of delaying the service response speed required for one transaction to be processed.

Therefore, when the number of attributes is n,

Declare as many signature arrays as consuming memory based on Map or Index data structure, but signing the requested attributes.

It is implemented so that it can go to time complexity.

Referring to FIG. 13, a signature that can verify only ProofOfAge among information of attributes is generated. ProofOfAge is an attribute that can confirm whether or not an adult is 18 years of age or older, and using this embodiment can provide a service that only adults, such as voting, can participate without disclosing personal information. Referring to FIG. 13(b), it can be seen that only ProofOfAge information has been released. As a result, it can be seen that when the configuration of the node 110, the authentication module 120, and the verification module 140 of this embodiment is utilized, it is possible to provide anonymity for personal information in a transaction generated in the blockchain network. .

In the above, the present invention has been described in detail with reference to examples, but those skilled in the art to which the present invention pertains will be capable of various substitutions, additions, and modifications without departing from the technical spirit described above. Of course, it should be understood that these modified embodiments also belong to the protection scope of the present invention as defined by the appended claims.

Claims

An authentication module for generating a first certificate;

A node generating a second certificate to which personal information is omitted and zero-knowledge applied and a transaction including the second certificate using the first certificate generated by the authentication module; And

A blockchain system that provides anonymity of personal information, comprising a verification module that verifies transactions generated at the node.
According to claim 1,

The authentication module generates an authentication public key and an authentication secret key using a randomizable digital signature, and generates the first certificate by signing with the authentication secret key using a BBS signature protocol. Blockchain system that provides information anonymity.
According to claim 2,

The node is a blockchain system that provides anonymity of personal information characterized by generating a second certificate to which zero knowledge is applied using a BBS signature protocol.
According to claim 3,

A blockchain system that provides anonymity of personal information, further comprising an audit module that tracks the transaction using a public key for auditing and a secret key for auditing.
According to claim 3,

A blockchain system that provides anonymity of personal information, further comprising a discard module that discards the second certificate that needs to be discarded and transmits the fact that the second certificate is discarded to a node.
(A) the authentication module generating a first certificate;

(B) the node using the first certificate to create a transaction that includes the second certificate and the second certificate to which personal information is omitted and zero-knowledge is applied; And

(C) A method for providing anonymity of personal information in a blockchain, wherein the verification module includes verifying the transaction.
The method of claim 6, wherein (A) step,

Generating an authentication public key and an authentication secret key using a randomizable digital signature; And

And generating the first certificate by signing the authentication secret key using the BBS signature protocol.
The method of claim 7, wherein (B) step,

A method for providing anonymity of personal information in a blockchain, characterized by using a BBS signature protocol when generating the second certificate.