KR20210127063A - Private Key backup Key recovery framework in a distributed service environment - Google Patents

Abstract

According to one embodiment of the present invention, a private key backup and restore method performed in a private key management system includes the steps of: duplicating a private key of a user node encrypted based on information for backing up the private key set in the user node by the number of trust groups according to a backup request of the private key of the user node, backing up the private key by dividing a cloned private key of the user node according to the number of user nodes in each trust group, distributing and storing it in a distributed service environment; and restoring the private key of the user node through the restoration information for restoring the private key stored in the distributed service environment provided as backup administrator's restoration authority for the user node and policy verification are performed in relation to a private key restoration request.

Description

{Private Key backup Key recovery framework in a distributed service environment}

The following description relates to a user private key backup and restoration framework in a distributed service environment.

The private key is encrypted with an arbitrary symmetric key, the encrypted private key is duplicated into several pieces, and the replicated key is divided into several pieces, and for each piece, the private key is re-encrypted with the public key of the participant trusted by the user, and distributed. Save and restore to environment. There are two types of related research fields as follows.

Referring to Non-Patent Document 1 <Wikipedia, "Key escrow", https://en.wikipedia.org/wiki/Key_escrow>, the key escrow method entrusts the key to an external trusted organization. . If the key is leaked by hacking, the entire private key of each user is stored in one place, so there is a risk of exposing the private key of all users in a distributed service environment such as a block chain.

Non-Patent Document 2 <Shamir, Adi. "How to share a secret." Referring to Communications of the ACM 22.11 (1979): 612-613.>, in the Secret Sharing Scheme, one individual's private key is fragmented into n, and each fragment is distributed and stored in several places. Among multiple variances, k or more must be gathered for restoration. Each piece is not encrypted. It is a method that relies on the computational complexity of polynomials on a finite field. At regular intervals, it must be divided into new pieces and stored again. This method is not suitable for distributed service environments such as blockchain.

In a distributed system-based service environment, sensitive data is encrypted and processed. In particular, since the asymmetric encryption method is used in a distributed system, it is very important to manage the user's private key. In a distributed service environment that does not have a central key management server, such as a blockchain, if a user dies or loses the private key, it is difficult to restore the private key. For example, if an individual cannot use the private key of an electronic wallet that stores Bitcoin, he cannot exercise his rights to his or her Bitcoin. In order to solve this problem, it is possible to provide a method and system for backing up and restoring a user's private key in a distributed service environment without a separate key management server.

In the private key backup and restore method performed in the private key management system, the private key of the user node encrypted based on the information for the private key backup set in the user node according to the private key backup request of the user node by the number of trust groups _{backing up} the private key by cloning, dividing the cloned private key of the user node according to the number of user nodes in each trust group (G i ), and distributing and storing it in a distributed service environment; and restore the private key of the user node through the restoration information for restoring the private key stored in the distributed service environment provided as the backup administrator's restoration authority and policy verification for the user node in relation to the private key restoration request are performed may include the step of

In the private key backup and restoration method, information of a trust group list (TGL) including the user node is transmitted from the user node to the backup manager, and the backup manager determines the trust group list (TGL) of the user node. It may further include the step of storing the information.

In the step of backing up the private key, a trust group list (TGL) designated for private key backup in a user node among a plurality of nodes existing in the distributed service environment, a backup manager, and the number of data to be distributed and stored in the distributed service environment are set. to prepare a private key backup, and _{randomly generate a symmetric key k to encrypt the private key A priv} of the user node, and use the generated symmetric key k to encrypt the private key A _priv ) to generate an encrypted private key (A' _priv ) of the user node by encrypting it.

Step to back up the private key, 'prior to dividing the _(priv, private key (A in the encrypted user node, the private key A)' of the encrypted user nodes by adding the information for encryption targeting _priv) First additional data (B _i ) is generated, the generated first additional data (B _i ) is duplicated by the number of trust groups, and the generated first additional data (B _i ) is used as a trust group list (TGL) It may include dividing based on the number of each user of the trust group (G _{i ) registered in the.}

)를 이용하여, 암호화된 사용자 노드의 개인키(A'_priv)를 신뢰 그룹 리스트(TGL)에 등록된 신뢰 그룹(G_i)의 각 사용자에 대응하여 분할된 분할 블록(B_i,j)을 암호화하여 상기 분할 블록(B_i,j)을 신뢰 그룹 리스트(TGL)의 각 신뢰 그룹(G_i)에 구성된 각 사용자의 공개키로 암호화한 제 1암호 블록(B'_i,j)을 생성하고, 상기 생성된 제 1 암호 블록(B'_i,j) 복원을 위한 정보를 추가한 제2 암호 블록(B''_i,j)을 생성하는 단계를 포함할 수 있다. In the step of backing up the private key, the public key of the j-th user registered in _{the trust group (G i ) (}

) by using the encrypted user node's private key (A' _{priv ) to correspond to each user of the trust group (G i} ) registered in the trust group list (TGL), the divided partition block (B _i,j ) encryption to generate the divided block (B _{i, j)} a first cryptographic block (B _{'i, j)} encrypted for each user of the public key comprised in each trust group (G _i) of the trusted group list (TGL) a, and It may include a step of generating a first encryption block (B _{'i, j)} by adding information for restoring the second encrypted block (B'_{'i, j)} the created.

Step to back up the private key, first symmetric for each trust group (G _i) any user (TU _{i, j)} using the public key of the node, the encrypted symmetric key (k) trust group (G _i) of the A key encryption value (k' _i ) is generated, and the generated first symmetric key encryption value (k' _i ) is encrypted with the backup manager's public key (BA _pub ), and the second symmetric key of the _{trust group (G i )} It may include performing a double encryption process including generating an encryption value (k'' _{i ).}

In the step of backing up the private key, the second symmetric key encryption value (k'' _{i ) of the created trust group (G i} ), the id of the user node backing up the private key (U _id ), the trust group list ( TGL) by adding the data of each trust group (G _i ) to configure the backup data for restoration (k backup data), the configured backup data (k backup data) and the second cipher block (B'' _i,j) ) may include the step of storing it in a distributed service environment.

In the step of restoring the private key, the agent in charge of restoring the private key of the user node submits data to the backup manager to prove that the agent in charge of restoring the private key of the user node or the owner of the user node private key, It may include the step of the backup manager reviewing whether the owner of the private key to be restored through the submitted data is a node registered in the Trust Group List (TGL).

In the step of restoring the private key, if the agent is a node existing in a trust group list (TGL) registered in the backup manager, generating an authentication certificate, encrypting the generated authentication certificate with the public key of the agent, The method may include digitally signing the backup manager's private key and delivering it to the agent.

In the step of restoring the private key, the agent restores the private key of the user node, and after confirming the electronic signature of the backup manager using the public key of the backup manager, the authentication certificate delivered from the backup manager , by using the agent's private key to decrypt the received authentication certificate, the user node's id (U _id ) from the distributed service environment and the data of each trust group (G _i ) in the trust group list (TGL) It may include obtaining the backup data (k backup data) and the second cipher block (B'' _{i,j ).}

In the restoring of the private key, the agent uses the id (U _id ) of the user node from the backup data and the data of each trust group (G _i ) of the trust group list (TGL) to a second symmetric key encryption value (k'' _i ) is extracted, the extracted second symmetric key encryption value (k'' _i ) and the authentication certificate are submitted to the backup manager, and as the authentication certificate is reviewed from the backup manager, the backup manager's Decrypting the extracted second symmetric key encryption value (k'' _i ) using the private key (BA _priv ) to obtain a first symmetric key encryption value (k' _i ), and the obtained first symmetric key encryption value (k' i) passing the value k' _i to the agent.

In the step of restoring the private key, the agent _{extracts the information for restoring the private key included in the second cipher block (B'' i,j} ) and the first cipher block (B' _i,j ), and trusts it. Request decryption by sending the authentication certificate, the cipher block and the first symmetric key encryption value (k' _i ) to the node (TU _{i,j ) of each trust group (G i} ) registered in the group list (TGL), node if from (TU _{i, j)} the agents are authenticated, each trust group (G _i), registered in the trust group list (TGL) of each trust group (G _i) registered in the trust group list (TGL) Decrypting the first cipher block (B' _i,j ) using the private key of the node to generate a split block (B _i,j ), and encrypting the symmetric key (k) in the trust group (G _{i ) The first symmetric key encryption value (k' i} ) is decrypted using the selected user node's private key to generate a symmetric key (k), and a partition block (B _i,j ) and It may include encrypting the symmetric key (k) and transmitting it to the agent.

In the step of restoring the private key, the agent decrypts the encrypted partition block (B _i,j ) and the symmetric key (k) with the agent's private key, and each trust registered in the trust group list (TGL) The first additional data (B _i ) is obtained from the node of the group (G _{i ) by using the partition block (B i,j} ), and the agent obtains additional information included in the obtained first additional data (B _{i )} After processing, the encrypted private key (A' _priv ) of the user node is decrypted, and the agent decrypts the encrypted private key (A' _priv ) of the user node using the symmetric key (k) to It may include restoring the key (A _{priv ).}

The private key management system for backing up and restoring the private key duplicates the private key of the user node encrypted based on the information for the private key backup set in the user node according to the private key backup request of the user node by the number of trust groups, , a private key backup unit for backing up the private key by dividing the duplicated information according to the number of user nodes in each trust group and distributing and storing the duplicated information in a distributed service environment; and restore the private key of the user node through the restoration information for restoring the private key stored in the distributed service environment provided as the backup administrator's restoration authority and policy verification for the user node in relation to the private key restoration request are performed It may include a private key restoration unit.

If you lose the electronic wallet that currently stores the block chain, it is the same as losing all electronic assets (lost all cash). In other words, there is a financial loss. However, if the method of the invention is used, if the electronic wallet is installed again and the private key is restored, one's electronic assets are fully revived.

Even if you do not lose your e-wallet and do not remember the private key information, you can safely recover your private key.

Even if the owner of the electronic wallet dies, the legal heir can recover the private key of the deceased, so that the electronic assets can be safely inherited.

1 is a diagram for explaining a general operation for private key backup and recovery in a private key management system according to an embodiment.
2 is a block diagram illustrating the configuration of a private key management system according to an embodiment.
3 is a flowchart illustrating a private key management method in a private key management system according to an embodiment.
4 is a diagram for explaining a private key backup operation in a private key management system according to an embodiment.
5 and 6 are diagrams for explaining a trust group list (TGL) in a private key management system according to an embodiment.
7 is an example for explaining a list of user nodes configured in a trust group list (TGL) in a private key management system according to an embodiment.
8 is a diagram for explaining the structure of _{the first additional data (B i} ) in the private key management system according to an embodiment.
FIG. 9 is a diagram for explaining the division structure of _{the first additional data (B i} ) in the private key management system according to an embodiment.
10 is a diagram for explaining a process of encrypting _{the first additional data (B i} ) in the private key management system according to an embodiment.
11 is a diagram for explaining the structure of _{the second cipher block (B'' i,j} ) in the private key management system according to an embodiment.
12 is a view for explaining a process of encrypting _{the second cipher block (B'' i,j} ) in the private key management system according to an embodiment.
13 is a diagram for explaining the structure of backup data in a private key management system according to an embodiment.
14 is a diagram for explaining a private key restoration operation in a private key management system according to an embodiment.
15 is a diagram for explaining a decryption process for a symmetric key (k) used for private key encryption in the private key management system according to an embodiment.
16 is a diagram for explaining a decryption process for a divided block in a private key management system according to an embodiment.
17 is a view for explaining a decryption process for _{the first additional data (B i} ) in the private key management system according to an embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

1 is a diagram for explaining a general operation for private key backup and recovery in a private key management system according to an embodiment.

The private key management system 100 is for performing private key backup and restoration, and a user node (User A node) 110, a trust group list (TGL) 130, a backup manager 140, and a distributed service environment system (150).

A user node (User A node) 110 may execute a private key backup as a user who wants to back up his/her private key in a distributed service environment (eg, a block chain system).

A trust group list (TGL: Trust Group List) 130 is a list of trust groups designated by the user node, and is a list of users authorized to restore the private key of the user node. Nodes registered in the Trust Group List (TGL) must be registered as users in a distributed service environment (eg, blockchain) where private keys are backed up.

The backup administrator (BA: Backup Admin) 140 is a backup administrator, which is a trusted third party designated by the user node, and refers to an organization that is involved in symmetric key restoration and issues a certificate indicating that it is a legitimate restoration requester.

The distributed service environment system 150 may store key information divided into the distributed service environment used by the user node 110 . 1 shows a blockchain service system as an example of a distributed service environment system that provides a distributed service environment. In the embodiment, a description will be made on the assumption that a blockchain service environment is used.

Referring to FIG. 1 , the nodes 110 and 130 that are major participants in this structure may be subscribed to the blockchain service system 150 . Here, the user node (user A node in the embodiment) 110 and each user of the trust group are all the same blockchain nodes. In an embodiment, the user node (user A node) 110 may be each individual in the trust group list (TGL) 130 at the same time. In the embodiment, it can be described based on the private key of the user node (A's electronic wallet, 'user node') subscribed to the blockchain service system. The block chain service system 150 may be users connected to the Internet 120 and subscribed to a specific block chain system (eg, Ethereum).

A specific node desiring to restore the private key may acquire information about the private key to be restored from the trust group list (TGL) 130 . Under the guarantee of the backup manager 140 , information on its own private key may be obtained from the trust group list (TGL). In other words, the backup manager serves to provide a certificate of guarantee to the third party who intends to restore the private key. Each node has various information (eg, static IP and port number) that can access the backup manager and the public key of the backup manager.

The backup manager 140 serves to issue a certificate to a requestor (node) requesting restoration of the private key. A certificate can be issued to a requestor after a specific authentication process (eg, online or offline, proving that the requestor is a person, or the requestor is a legal heir, etc.). The certificate issued at this time contains information such as {private key owner information, requester's ID}. Information of a trust group list (TGL) including the user node 110 may be transmitted from the user node 110 to the backup manager 140 . The backup manager 140 may store information of the Trust Group List (TGL) for the user node 110 .

In this way, based on the data that the user node (the node that wants to be backed up and the node of the trustee) and the backup manager basically has, the operation of backing up based on a specific user node (for example, if it is called Node A here) is shown in FIG. 4 .

Each node must have <private key, public key> and backup manager information of each node when installing the electronic wallet. In other words, Data Structure of Node_i= {<private key, public key>, BackupAdmin Info} is done. Here, BackupAdmin Info is the information of the backup administrator. Here, the node's private key is denoted as _{A priv .} The backup manager information includes the backup manager's public key (BA _pub ), and for communication, the URL of the backup manager server or IP address and port information may be additionally included.

In addition, in order to back up the node's own private key to the block chain, information on the Trust Group List (TGL) must be stored. This Trust Group List (TGL) information can be created when starting a backup. In addition, when another node designates itself as a target of a trust group, the electronic wallet ID of another participant who has designated itself as a target of the trust group may be stored in its node information. Therefore, the minimum data structure required is

Data Structure of Node_i= { <private key, public key>,

BackupAdmin Info,

{Trust Group List info},

{List of Trustee info } }

can be composed of The { } symbol in the symbol indicates a set (many).

Referring to FIG. 6 , a trust group list (TGL) includes an id of a target node and a public key of the target node. At least one group participates in the trust group list (TGL). Each group plays a role in encrypting the same private key differently for each trust group (G _{i ).} That is, the contents are duplicated and stored. However, since the private key is encrypted with the public key of each node participating in the target, they all have different values in form. For example, there are three groups for the participants that _{U id trusts, and the first group (G 1} ) is three participants, respectively, TU _1,1 , TU _1,2 , and TU _1,3 , and the second Group (G ₂ ) has 2 participants (TU _2,1 , TU _2,2 ), and the third group (G ₃ ) has 4 participants (TU _3,1 , TU _3,2 , TU _3,3 , TU _3,4 ), and consists of a total of 9 people. Here, TU _x,y means the x-th group and the y-th trustee. In general, there are n groups (n >=1), and the _{number of participants in the i group is m i at} least 1 or more. Each group in the TGL and the number of members in each group may be different.

The trust group list (TGL) may be expressed as in Equation (1). The trust group list (TGL) may be represented as shown in FIG. 5 .

Equation 1:

Referring to FIG. 7 , it is an example for describing a list of user nodes configured in the trust group list (TGL). A list of user nodes (List of Trustee Info) configured in the trust group list (TGL) may be composed of the id of the target node or a set of the id of the target node and a set of agents (inheritors) designated by the target node. There can be two ways to organize this list, depending on how the backup/restore system works. _{For example, TU 1,1} , one of the participants trusted by user A, firstly has a list of participants who put it in the trust group, and secondly, it consists of a list of participants and a list of heirs designated by the participant. . In the first case, TU _1,1 knows the restoration performer during restoration later. In the second case, TU _1,1 has both a list of participants and a list of heirs (TGL), so when a restoration performer who requests restoration in the future makes a restoration request, it can perform/reject restoration by comparing it with his/her own list. In this case, for example, it means that _{the heirs of U a} (or the requestor of restoration later) can have {U _a , U _a1 ,..U _ax } including themselves. However, in the case of inheritance, whether or not the heir knows the contents of inheritance in advance may be different, so the user selectively configures the list of user nodes configured in the trust group list (TGL) when backing up. A method of configuring the list of user nodes configured in the trust group list (TGL) is not limited in the embodiment because it is a policy.

2 is a block diagram illustrating the configuration of a private key management system according to an embodiment, and FIG. 3 is a flowchart illustrating a private key management method in the private key management system according to an embodiment.

The processor of the private key management system 100 may include a private key backup unit 210 and a private key restore unit 220 . These components of the processor may be representations of different functions performed by the processor according to control instructions provided by program code stored in the private key management system. The processor and components of the processor may control the private key management system to perform steps 310 to 320 included in the private key management method of FIG. 3 . In this case, the processor and components of the processor may be implemented to execute instructions according to the code of the operating system and the code of at least one program included in the memory.

The processor may load the program code stored in the file of the program for the private key management method into the memory. For example, when a program is executed in the private key management system 100 , the processor may control the private key management system 100 to load a program code from a file of the program into the memory according to the control of the operating system. At this time, each of the processor and the private key backup unit 210 and the private key restoration unit 220 included in the processor executes the commands of the corresponding portions of the program codes loaded in the memory to execute the subsequent steps 310 to 320 . may be different functional representations of a processor for

In step 310, the private key backup unit 210 copies the private key of the user node encrypted based on the information for the private key backup set in the user node according to the private key backup request of the user node by the number of trust groups, The private key can be backed up by dividing the replicated information according to the number of user nodes in each trust group and storing it in a distributed service environment. In this case, the user node may be a backup target node. A description of the private key backup operation will be described in more detail with reference to FIG. 4 .

), 백업 관리자의 공개키(BA_pub)를 포함하는 백업에 사용되는 데이터를 사용자 노드에 저장할 수 있다. Referring to FIG. 4 , an eight-step process for backing up the private key may be performed. The user node may prepare a private key backup ( 410 ). The private key (A _priv ) of the user node, the symmetric key (k) randomly generated in the user node, and the public key of the mth user registered in the _{nth trust group (G i )}

) and the backup manager's public key (BA _pub ), data used for backup can be stored in the user node.

Information of a trust group list (TGL) including the user node may be transmitted from the user node to the backup manager. The backup manager may store information in the Trust Group List (TGL) for the user node 110 .

A user node may randomly generate a symmetric key k for both encryption and decryption ( 420 ). In this case, the symmetric key k may be used to encrypt _{the private key A priv of the user node.} The encryption algorithm used here uses an algorithm designated as a standard, but is not limited. However, the length of the key may vary depending on the algorithm used. The embodiment does not limit the length.

_{The user node may encrypt the private key A priv} of the user node using the _{symmetric key k to generate the private key A' priv} of the user node encrypted with the symmetric key k ( 430 ).

The user node may add necessary data for each encryption algorithm (eg, an error compensation code (Cyclic Redundancy Code), Padding, etc.). In the embodiment, the error compensation code will be described as an example. The user node may calculate an error compensation code (CRC: Cyclic Redundancy Code) ( 440 ). The user node may generate an error compensation code for _{the private key (A' priv} ) of the user node encrypted with the symmetric key (k). At this time, the error compensation code is an error compensation code for the target data (here, the private key (A' _priv ) of the user node encrypted with the symmetric key (k)), that is, when a part of the data is changed for an unspecified reason, value that can be The length of the private key is determined according to the algorithm used. For example, an error compensation code of a certain length may be determined according to 128 bits or 256 bits.

Referring to FIG. 8 , the structure of information (first additional data B _{i ) finally generated through 410 to 440 is shown. In other words, the error compensation code value 820 for the private key (A' priv} ) 810 of the user node encrypted with the symmetric key k and the private key of the encrypted user node is the first additional data (B _i ) (800). _{More specifically, the finally generated first additional data (B i} ) 800 may be obtained by adding a padding value based on the length to which the error compensation code is added. _{For example, if the length of adding the private key (A'priv} ) of the user node encrypted with the symmetric key and the error compensation code is not a multiple of the number of nodes in each group m _i , a padding value is added to the first additional data ( B _i ) 800 can be generated.

)(1020)를 이용하여 분할 블록(B_i,j)을 암호화하여 분할 블록(B_i,j)을 신뢰 그룹 리스트(TGL)의 각 그룹(G_i)에 구성된 각 사용자의 공개키로 암호화한 제 1암호 블록(B'_i,j)을 생성할 수 있다. 다시 말해서,

이다. 분할 블록(B_i,j)을 이용하여 신뢰 그룹 리스트(TGL)의 각 그룹(G_i)에 구성된 각 사용자의 공개키(

)(1020)로 암호화한 제 1암호 블록(B'_i,j)(1120)을 생성한 후, 제 1암호 블록(B'_i,j)(1120)에 복원을 위한 블록 정보를 추가한 제2 암호 블록(B''_i,j)(1110)를 생성할 수 있다. 복원에 필요한 정보는 U_id(1130), G_i(1140), seq(1150)이다. 여기서, U_id(1130)은 사용자 노드의 id이고, G_i(1140)은 그룹의 번호이고, seq(1150)은 그룹 내에서 분할된 블록의 순서 정보를 의미한다.User nodes can perform parallel processing of the Trust Group List (TGL). The user node may duplicate the first additional data (B _{i ) as much as the number of groups (G i} ) of the trust group list (TGL). In this case, the value of the first additional data (B _i ) may be divided ( 450 ) based on the number of each node configured in all the trust groups G ₁ , G ₂ ,??, and G _{n .} The structure of the first additional data B _i divided for each trust group may be represented as shown in FIG. 9 . 9, the same first additional data (B _i ) is divided into four for group 1 (G _{1 ), divided into three for group 2 (G 2} ), and divided into _{two for group 3 (G 3} ). can be divided However, when applied to the system, since the algorithms used for encryption and decryption are all the same, the size of the value sent to each node of the trust group must always be the same. Accordingly, it is necessary to pad each of the divided first additional data (eg, B _1,1 , B _1,2 , B _1,3 , and B _{1,4 of} 910 ) by a required length. For example, assuming that each of the first additional data is 100 bits (400 bits in total), and the length of each transmission data is 256 bits, a specific value (for example, 0 ) is filled with If it is divided into two pieces of data (eg, number 730, B _3,1 , & B _3,2 ), the total is 400 bits, and each is divided into 200 bits, so the information to be padded is 56 bits each. . This padded data will be referred to as a _{partition block (B i,j ).} The user node may encrypt 460 the _{partition block (B i,j ).} 10 and 11, the public key of the j-th user registered in the i-th trust group (G _{i ) (}

) 1020 to encrypt the partition block (B _i,j ) to encrypt the partition block (B _i,j ) with the public key of each user configured _{in each group (G i} ) of the trust group list (TGL). One cipher block (B' _i,j ) can be created. In other words,

am. Divided blocks (B _{i, j)} of the public, each user is configured for each group (G _i) of the trusted group list (TGL) using a key (

After generating the first cipher block (B' _i,j ) 1120 encrypted with ) (1020), the first cipher block (B' _i,j ) (1120) with block information for restoration added 2 cipher blocks (B'' _i,j ) 1110 may be generated. Information required for restoration is U _id (1130), G _i (1140), and seq (1150). Here, U _id 1130 is an id of a user node, G _i 1140 is a group number, and seq 1150 means order information of blocks divided within the group.

Referring to FIG. 12 , the symmetric key (k) 1200 may be double encrypted (470) without being divided. A symmetric key (k) 1200 is encrypted using the public key of a random user node (TU _i,j ) of each group (eg, the first user (TU _{i,1 ) of each group) 1210} A first symmetric key encryption value (k' _i ) 1220 may be generated. Then, the first symmetric key encryption value (k' _i ) 1220 is encrypted with the backup manager's public key (BA _pub ) 1230 to generate the second symmetric key encryption value (k'' _i ) 1240 . can A double encryption process may be performed for all trust groups (G _{i ).} At this time, although the same symmetric key (k), each second symmetric key encryption value (k'' _{i ) performed and output for each trust group (G i} ) is different.

After generating the second symmetric key cryptographic value (k'' _i ) 1310 of FIG. 13, the user node's id (U _id ) (1320) and the number (G _i ) (1330) of all trust groups are added. Backup data (k backup data 1300) that can be used in the restoration process may be generated.

A plurality of different backup data (k backup data) generated in the electronic wallet and the second cryptographic block (B'' _i,j ) with block information for restoration added to each cryptographic block can be distributed and stored in the block chain. (480).

In step 320, the private key restoration unit 220 restores the private key restoration information stored in the distributed service environment provided as the restoration authority and policy verification for the user node of the backup manager are performed in relation to the private key restoration request. can restore the user node's private key. In this case, the user node may be a backup request node in which the private key is backed up. A description of the private key restoration operation will be described in more detail with reference to FIG. 14 .

)이다. 여기서, 제2 암호 블록(B''_i,j)와 제2 대칭키 암호값(k''_i)는 분산 서비스 환경(예를 들면, 블록체인)에 저장되어 있고, i번째 신뢰 그룹(G_i)에 등록된 j번째 노드의 개인키(

)는 각 사용자 노드에 저장되어 있고, 백업 관리자의 개인키(BA_priv)는 백업 관리자에 저장될 수 있다. Referring to FIG. 14 , the process of step 8 for restoring the private key may be performed. At this time, the data used for restoration includes a second cipher block (B'' _i,j ) to which block information for restoration is added, a second symmetric key encryption value (k'' _i ), and the private key of the backup manager (BA _priv). ), the private key of the j-th node registered in the i-th trust group (G _{i )}

)am. Here, the second cipher block (B'' _i,j ) and the second symmetric key cryptographic value (k'' _i ) are stored in a distributed service environment (eg, blockchain), and the i-th trust group (G The private key of the j-th node registered in _{i ) (}

) is stored in each user node, and the backup manager's private key (BA _priv ) may be stored in the backup manager.

The backup manager may certify the agent ( 1410 ). The agent performing the restore process (original owner or legal representative) may submit to the backup administrator any necessary documentation proving that the agent is a legitimate agent acting on behalf of the owner of the private key or the owner of the private key. This document must be submitted online or offline, and the method of submission may be determined by policy. The backup administrator can review the document to see if the agent is a registered user in the Trust Group List (TGL) specified by the owner of the private key to be restored. In this case, the document may be a certificate (or notarization) proving that the agent is a representative of the user node. In addition, when a user node creates a Trust Group List (TGL) to leave its electronic assets as a legacy, the document may be a death certificate of the user node. Assuming that the user node is dead, the agent can represent each node (T _i,j ) and submit the identity certificate along with the death certificate of the user node to the backup manager. If the user himself loses the private key, the same process can be applied based on the identity certificate instead of the death certificate. These requirements can be processed according to the policy for restoration.

When all documents submitted by the agent are verified and registered in the trust group list (TGL) registered by the agent in the backup manager, the backup manager can generate a certification certificate (Vcert). At this time, the authentication certificate (Vcert) is an authentication certificate provided by the backup manager to a legitimate requester, and means a certificate or an electronic certificate that can prove that the _{restoration requester is a legitimate requester registered in the trust group (G i ).} The authentication certificate (Vcert) is the agent's id, the node's ID (U _id ) using the backup of all private keys in the trust group, and the j-th node registered in the i-th trust group (G _{i ) of the trust group list (TGL).} It may include content indicating (TU _{i,j ).} The backup manager may encrypt the authentication certificate (Vcert) with the agent's public key and deliver data digitally signed with the backup manager's private key to the agent.

The agent can restore the private key to be restored from the agent's node. The user node may receive the backup data (k backup data) and the second cipher block (B'' _i,j ) to which block information for restoration is added to the data used for restoration ( 1420 ). The agent verifies that the transfer signature is correct with the backup manager's public key. If it is, the agent can decrypt the data with the agent's private key. The decrypted information may be a certification certificate (Vcert), where the user ID (U _id ) and each trust group (G _i ) of the trust group list (TGL) are extracted and requested to the corresponding distributed service environment. . The agent uses the user ID (U _id ) and each trust group (G _i ) of the trust group list (TGL) from the distributed service environment to obtain backup data (k backup data) and the second cipher block (B'' _i,j) ) can be obtained. In the second cipher block (B'' _i,j ), the user's ID (U _id ), trust group (G _i ) number, sequence information (seq) of blocks divided within the trust group, and the first cipher block (B') _i,j ) may be included.

The backup manager may decrypt the second symmetric key encryption value (k'' _i ) ( 1430 ). The agent may extract the second symmetric key encryption value (k'' _i ) from the backup data (k backup data). In this case, the user ID (U _{id ) and each trust group (G i} ) of the trust group list (TGL) may also be extracted. The agent may submit the extracted second symmetric key encryption value (k'' _i ) and the authentication certificate (Vcert) to the backup manager online or offline. The backup administrator reviews the authentication certificate (Vcert) and, if appropriate _{, uses the backup administrator's private key (BA priv} ) to decrypt each second symmetric key encryption value (k'' _i ) to decrypt the first symmetric key encryption value ( k' _i ) can be extracted. The extracted first symmetric key encryption value (k' _i ) may be delivered to the agent.

The agent can be extracted second encrypted block (B '' _{i, j)} the first ciphertext block (B that correspond to the user's identity (U _id) included in the _{'i, j).} The agent extracts the first cipher block (B' _i,j ) corresponding to the id (U _id ) of the user node included in the second cipher block (B'' _i,j ), and adds it to the trust group list (TGL). Request for decryption by sending the authentication certificate, the first cipher block (B' _i,j ), and the first symmetric key encryption value (k' _i ) to the node (TU _i,j ) of each registered trust group (G _{i )} may (1440). In this case, the agent's id and authentication certificate (Vcert) may also be transmitted. In addition, when the user's ID (U _id ) is a target required for symmetric key restoration (that is, _{the target that receives the first symmetric key encryption value (k' i} ) from the backup manager), the first symmetric key encryption value (k') _i ) can also be transmitted.

15 and 16, the j-th user (TU _i,j ) registered in the i-th trust group (G _i ) of the trust group list (TGL) uses the node's private key 1620 when the agent is authenticated Thus, the first cipher block (B' _i,j ) 1610 may be decrypted to generate a split block (B _i,j ) 1630 ( 1450 ). In addition, when the user is the target, the symmetric key (k) 1530 may be generated by decrypting _{the first symmetric key encryption value (k′ i ) 1510 with the private key 1520 of the node.}

The j-th user (TU _i,j ) registered in the i-th trust group (G _{i ) of the trust group list (TGL) transmits the partition block (B i,j} ) and the symmetric key (k) to the agent as the agent’s public key. can The operation of restoring the symmetric key (k) is illustrated in FIG. 15 and _{the process of restoring the partition block (B i,j} ) is illustrated in FIG. 16 . In other words, the first symmetric key encryption value (k' _i ) is assigned to an arbitrary user node (TU _i,j ) of each trust group (G _i ) (for example, the first user node (TU _{i,1 ) of each trust group} ))), a symmetric key (k) is generated, and the first encryption block (B' _i,j ) is the j-th user registered in the i-th trust group (G _{i ) of the trust group list (TGL).} When decrypting with the private key of (TU _{i,j ), a partition block (B i,j} ) can be generated.

The j-th user (TU _i,j ) registered in the i-th trust group (G _i ) of each trust group list (TGL) encrypts the partition block (B _i,j ) and the symmetric key (k) with the agent’s public key can be transmitted. The agent can decrypt the encrypted partition block (B _i,j ) and the symmetric key (k) with the agent's private key. When the agent assembles the partition block (B _i,j ) received from the j-th user (TU _i,j ) registered in the i-th trust group (G _i ) of all trust group lists (TGL) in order, additional data ( B _i ) becomes (FIG. 17). At this time, since at least one group (G _i ) exists in the trust group list (TGL), the first additional data (B _i ) is also one or more.

_{Since the agent knows the bit length of the user node's private key (A' priv} ) encrypted with the error compensation code (CRC) and the symmetric key (k) contained in the additional data (B _i ), the padding is removed and the symmetric key (k) The error compensation code (CRC) of the private key (A' _priv ) of the encrypted user node is calculated again and compared with the error compensation code (CRC) extracted from _{the additional data (B i ).} . If there is no abnormality, the private key (A' _priv ) of the user node encrypted with the symmetric key (k) can be decrypted. This process may be performed on additional data (B _i ) of the trust group (G _{i ) performing restoration.}

The agent can restore _{the original private key (A priv} ) by performing decryption using the symmetric key (k) on the encrypted private key (A' _{priv) of the user node.}

The device described above may be implemented as a hardware component, a software component, and/or a combination of the hardware component and the software component. For example, devices and components described in the embodiments may include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA). , a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions, may be implemented using one or more general purpose or special purpose computers. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For convenience of understanding, although one processing device is sometimes described as being used, one of ordinary skill in the art will recognize that the processing device includes a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that can include For example, the processing device may include a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as parallel processors.

The software may comprise a computer program, code, instructions, or a combination of one or more thereof, which configures a processing device to operate as desired or is independently or collectively processed You can command the device. The software and/or data may be any kind of machine, component, physical device, virtual equipment, computer storage medium or device, to be interpreted by or to provide instructions or data to the processing device. may be embodied in The software may be distributed over networked computer systems, and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

The method according to the embodiment 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, etc. alone or in combination. The program instructions recorded on the medium may be specially designed and configured for the embodiment, or may be known and available to those skilled in the art of computer software. Examples of the computer-readable recording medium include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic such as floppy disks. - includes magneto-optical media, and hardware devices specially configured to store and carry out program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like.

As described above, although the embodiments have been described with reference to the limited embodiments and drawings, various modifications and variations are possible from the above description by those skilled in the art. For example, the described techniques are performed in a different order than the described method, and/or the described components of the system, structure, apparatus, circuit, etc. are combined or combined in a different form than the described method, or other components Or substituted or substituted by equivalents may achieve an appropriate result.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (13)

In the private key backup and restore method performed in the private key management system,
According to the private key backup request of the user node, based on the information for the private key backup set in the user node, the encrypted private key of the user node is copied as much as the number of trust groups, and the duplicated information is copied to each trust group (G _i ) backing up the private key by dividing it according to the number of user nodes and storing it distributedly in a distributed service environment; and
Restoring the private key of the user node through the restoration information for restoring the private key stored in the distributed service environment provided as the backup administrator's restoration authority for the user node and policy verification are performed in relation to the private key restoration request step
Private key backup and restore method, including. According to claim 1,
transmitting information of a trust group list (TGL) including the user node from the user node to the backup manager, and storing information of the trust group list (TGL) of the user node by the backup manager
Private key backup and restore method further comprising. According to claim 1,
The step of backing up the private key comprises:
Among a plurality of nodes existing in the distributed service environment, the user node prepares the private key backup by setting the trusted group list (TGL) designated for private key backup, the backup manager, and the number of data to be distributed and stored in the distributed service environment, and To encrypt the private key (A _priv ) of the user node, a symmetric key (k) is randomly generated, and the private key (A _priv ) is encrypted using the generated symmetric key (k) to encrypt the private of the user node. key (a 'generate _priv), and the private key (a in the encrypted user node, add the private key information for encryption to the target (a' _priv) before dividing the _priv), the encrypted user node the first supplemental data (B _i) to generate and replicate as many as the number of first additional data (B _i) the trust group (G _i) the generated and the first additional data (B _i) the generated trust Splitting based on the number of each user _{in the trust group (G i} ) registered in the group list (TGL)
Private key backup and restore method, including. 4. The method of claim 3,
The step of backing up the private key comprises:
The public key of the j-th user registered in the trust group (G _{i ) (}

) using the encrypted user node's private key (A' _priv ) to generate a divided partition block (B _i,j ) _{corresponding to each user of each trust group (G i} ) registered in the trust group list (TGL). A first cipher block (B' _i,j ) obtained by encrypting the divided block (B _i,j ) with the public key of each user configured in each trust group (G _i ) of the trust group list (TGL) is generated, Generating a second cipher block (B'' _i,j ) in which block information for restoration is added to the generated first cipher block (B' _i,j )
Private key backup and restore method, including. 5. The method of claim 4,
The step of backing up the private key comprises:
First symmetric key encrypted value for each trust group (G _i) any of the user node (TU _{i, j)} symmetric key (G _i) trusted group password to (k) using the public key of the (k _'i) generated and the 'second symmetric key encryption value (k in the _(i encrypted with the public key (BA _pub) in backup manager trust group (G _{i), i)} the generated first symmetric key encrypted value k), the performing a double encryption process including generating
Private key backup and restore method, including. 6. The method of claim 5,
The step of backing up the private key comprises:
The second symmetric key encryption value (k'' _i ) of the created trust group (G _{i ), the id (U id} ) of the user node backing up the private key, _{and each trust group (G i} ) of the trust group list (TGL) ) to configure the backup data (k backup data) for restoration by adding the data of, and storing the configured backup data (k backup data) and the second cipher block (B'' _i,j ) in a distributed service environment
Private key backup and restore method, including. According to claim 1,
Restoring the private key comprises:
The agent in charge of restoring the private key of the user node submits data to the backup manager to prove that the agent in charge of restoring the private key of the user node or the owner of the user node private key is provided, and the backup manager stores the submitted data The step of reviewing whether the owner of the private key to be restored is a node registered in the Trust Group List (TGL) through
Private key backup and restore method, including. 8. The method of claim 7,
Restoring the private key comprises:
When the agent is a node existing in the Trust Group List (TGL) registered with the backup manager, an authentication certificate is generated, the generated authentication certificate is encrypted with the agent's public key, and digitally signed with the backup manager's private key. Steps to Forward to Agent
Private key backup and restore method, including. 9. The method of claim 8,
Restoring the private key comprises:
The agent restores the user node's private key, and after confirming the electronic signature of the backup manager using the backup manager's public key for the authentication certificate delivered from the backup manager, the agent's private key is used to restore the user node's private key. and backup data (k backup data) by using the data of each trust group (G _i) of the id (U _id) and a trust group list (TGL) in the user's node from the distributed services environment as decoding the transmission by a certified certificate claim Step 2 to obtain a cipher block (B'' _{i,j )}
Private key backup and restore method, including. 10. The method of claim 9,
Restoring the private key comprises:
In the agent, a second symmetric key encryption value (k'' _i ) is extracted from the backup data by using the id of the user node (U _id ) and the data of each trust group (G _{i ) of the trust group list (TGL),} , the extracted second symmetric key encryption value (k'' _i ) and the authentication certificate are submitted to the backup manager, and as the authentication certificate is reviewed from the backup manager, the backup manager's private key (BA _priv ) is used to The extracted second symmetric key encryption value (k'' _i ) is decrypted to obtain a first symmetric key encryption value (k' _i ), and the obtained first symmetric key encryption value (k' _i ) is sent to the agent. step to pass
Private key backup and restore method, including. 11. The method of claim 10,
Restoring the private key comprises:
In the agent, the first cipher block (B' _{i,j ) corresponding to the id (U id} ) of the user node included in the second cipher block (B'' _i,j ) is extracted, and the trust group list (TGL) Send the authentication certificate, the cipher block, and the first symmetric key encryption value (k' _i ) to the node (TU _i,j ) of each trust group (G _i ) registered in to request decryption, and the trust group list ( When the agent is authenticated from the node (TU _i,j ) of each trust group (G _i ) registered in TGL), the private key of the node of _{each group (G i} ) registered in the trust group list (TGL) is used to decrypt the first cipher block (B' _i,j ) to generate a divided block (B _i,j ), and to encrypt the symmetric key (k) in the trust group (G _{i )} The first symmetric key encryption value (k' _i ) is decrypted using the key to generate a symmetric key (k), and a partition block (B _i,j ) and a symmetric key (k) are generated using the agent's public key. Encrypted and delivered to the agent
Private key backup and restore method, including. 12. The method of claim 11,
Restoring the private key comprises:
The agent decrypts the encrypted partition block (B _i,j ) and the symmetric key (k) with the agent's private key, and splits from the node _{of each trust group (G i ) registered in the trust group list (TGL)} Obtaining the first additional data (B _i ) using the block (B _{i,j ),}
After the agent processes the additional information included in the obtained first additional data (B _i ), and compares the error compensation code of the _{calculated private key (A' priv) of the encrypted user node,} Decrypt the private key ( _A'priv),
Decrypting the encrypted private key (A' _priv ) of the user node by the agent using a symmetric key (k) to restore the _{private key (A priv) of the user node}
Private key backup and restore method, including. In the private key management system for private key backup and restoration,
According to the private key backup request of the user node, the private key of the user node encrypted based on the information for backing up the private key set in the user node is copied as many as the number of trust groups, and the private key of the cloned user node is copied to each trust group a private key backup unit that backs up the private key by dividing it according to the number of user nodes of (G _{i ) and storing it distributedly in a distributed service environment;} and
Restoring the private key of the user node through the restoration information for restoring the private key stored in the distributed service environment provided as the backup administrator's restoration authority for the user node and policy verification are performed in relation to the private key restoration request private key recovery unit
A private key management system comprising a.

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