KR20220066801A - Method and appratus for providing blackchain-based secure messenger service - Google Patents

Abstract

Disclosed are a method and device for providing a blockchain-based secure messenger service. As the method for the blockchain-based secure messenger service executed by a first user terminal of a transmitter, the method for the blockchain-based secure messenger service comprises: a step of encrypting a message to be transmitted to a second user terminal of a receiver; a step of transmitting the encrypted message to a centralized messenger server; a step of acquiring the input message data transmitted to the centralized messenger server; a step of issuing a blockchain-based non-fungible token for the input message data; and a step of transmitting the non-fungible token to the second user terminal. Therefore, the present invention is capable of having an advantage of being highly usable.

Description

Blockchain-based secure messenger service method and device

The present invention relates to a secure messenger service, and more particularly, to a method and apparatus for providing a block chain-based secure messenger service.

The messenger service is the most actively used communication method since the introduction of smartphones. Representative commercial messenger services include KakaoTalk, Line, and Telegram. In this commercial messenger service environment, users have to rely on a centralized messenger service provider for everything when sending or receiving messages.

When a user sends/receives a very important message with a legal meaning through the messenger service, the following four additional functions are required. In other words, it is necessary to authenticate the identity of the other party of the message, guarantee the confidentiality of the message content sent/received, prove the integrity of the message content sent/received, and prove the non-repudiation of the message sending/receiving act.

However, there is a problem that the centralized messenger service, which the user has to rely entirely on all functions, is vulnerable to forgery or falsification by internal administrators or external hacking attacks, and thus cannot support the four functions essential for sending and receiving legal messages.

The present invention was derived to solve the problems of the prior art described above, and an object of the present invention is to utilize a commercial messenger service when a user transmits an important message having a legal meaning, and to authenticate the identity of the message counterpart, which is essential for support; It aims to provide a blockchain-based secure message service method that can support four functions: guaranteeing the confidentiality of transmitted/received message contents, verifying the integrity of transmitted/receiving message contents, and proof of non-repudiation of message sending/receiving actions.

Another object of the present invention is to provide a block-chain-based security message service device for the above-described block-chain-based security message service method.

A block chain-based secure messenger service method according to an aspect of the present invention for solving the above technical problem is a block chain-based secure messenger service method executed by a first user terminal of a sender, and is transmitted to a second user terminal of a receiver encrypting the message or attachment; transmitting the message encrypted in the encrypting step to a second user terminal through a centralized messenger server; issuing a blockchain-based non-fungible token corresponding to the encrypted message; and transmitting the non-fungible token to the second user terminal.

In one embodiment, the encrypting encrypts the message or the attached file using the public key of the recipient.

In one embodiment, the block chain-based secure messenger service method may further include changing the owner of the non-fungible token to the recipient after the issuing step.

In an embodiment, the first user terminal and the second user terminal may have a public key infrastructure key pair authenticated by a certificate authority.

In one embodiment, the properties of the non-fungible token may include token identifier (ID), token type, owner information, sender messenger ID, receiver messenger ID, message content encryption symmetric key information, expiration date, and token inquiry status information. have.

In one embodiment, the non-fungible token includes a token attribute for token generation and transmission transaction processing information, wherein the sender or receiver non-repudiates whether a message has been sent or received via the token generation and transmission transaction processing information. proof can be obtained.

In one embodiment, the non-fungible token includes a token attribute for a validity period, where the sender or receiver can self-determine message validity through the validity period.

In an embodiment, the first user terminal and the second user terminal are messenger clients that transmit and receive signals and data through a centralized messenger server, and may use Extensible Messaging and Presence Protocol (XMPP) or a messenger protocol itself.

In one embodiment, the sender may verify the recipient's non-repudiation of receipt via the token inquiry status attribute of the non-fungible token. Alternatively, the receiver verifies the identity of the sender by checking the sender signature and messenger ID recorded in the non-fungible token by inquiring the non-fungible token, or sends an encrypted message through the message encryption symmetric key corresponding to the public key of the recipient. can be decrypted.

In one embodiment, the method further comprises: obtaining a user input or command from a user interface for selecting transmission of a non-secure message and transmission of a secure message from the first user terminal or the second user terminal, according to the user input or command A series of processes including encrypting the message, transmitting the encrypted message, issuing the message token, and transmitting the message token may be performed.

In one embodiment, the attached file of the photo, video, document data, or a combination thereof included in the message is stored in an off-chain space accessible through a network, and the non-fungible token is a storage path of the off-chain space for the attachment. can be recorded.

In one embodiment, the blockchain-based secure messenger service method obtains encrypted attachment data of an attachment on the messenger screen of the first user terminal, and a block-chain-based non-replaceable additional token for the encrypted attachment data The method may further include providing a user interface for issuing and transmitting the non-fungible additional token to the second user terminal.

A block chain-based secure messenger service apparatus according to an aspect of the present invention for solving the above technical problem is a block-chain-based secure messenger service apparatus mounted on a first user terminal of a sender, and a message to be transmitted to a second user terminal of a receiver a message processing unit for transmitting the encrypted message of the attached file to the second user terminal through a centralized messenger server; and a token processing unit that acquires input message data for the encrypted message, issues a blockchain-based non-fungible token for the input message data, and transmits the non-fungible token to the second user terminal.

In one embodiment, the token processing unit, the token issuance module to obtain the input message data for the encrypted message and to issue a blockchain-based non-fungible token for the input message data; a token transmission module for transmitting a non-fungible token to a second user terminal; and a token modification module for changing the owner of the non-fungible token to a recipient.

In one embodiment, the token processing unit further includes a token inquiry module that generates a transaction for inquiring the properties of the message token and transmits the generated transaction to the block chain to inquire the encryption symmetric key of the message token.

In one embodiment, the token processing unit further includes an event management module that receives an event from the block chain when the operation result for the message token by the token issuing module, the token sending module and the token modifying module is finally stored in the block chain. be prepared

In an embodiment, the token processing unit calls the token verification module to check the counterpart's messenger ID recorded in the message token, and matches the user information and public key corresponding to the counterpart's messenger ID with the counterpart's user information and public key By comparing whether or not, the user identity of the other party is authenticated.

In an embodiment, the secure messenger including the messenger processing unit and the token processing unit may select non-secure message transmission and secure message transmission according to a specific input or command from a user interface provided on the messenger service screen of the user terminal.

According to the present invention described above, the message transmitted by the user is encrypted and transmitted, and related metadata such as encryption key information, transmission information, and recipient ID of the message are stored as an irreplaceable token on the block chain and transmitted to the recipient, The integrity and confidentiality of the message content can be guaranteed with the security level of the blockchain.

In addition, according to the present invention, a user can transmit a general plaintext message that does not utilize a block chain or transmit a secure message using a block chain-based secure messenger service according to the importance of the message to be transmitted, so the existing centralized messenger The service and blockchain-based secure messenger service can be used together, and in particular, since it can be implemented as an additional function of the existing commercial messenger service, its usefulness is high.

In addition, according to the present invention, it is possible to obtain identity authentication for message senders and receivers by utilizing token owner information on the block chain through the generation and transmission of non-fungible tokens on the block chain and change of the token owner, and also token generation and Through the transmission transaction processing information, it is possible to provide non-repudiation proof of whether a message is sent or received at the security level of the blockchain.

In addition, according to the present invention, by setting the validity period of the non-fungible token as a token attribute, even if the centralized commercial messenger service independently implements a message storage policy, the user can finally determine the validity of the message through the token validity period. can do.

In addition, according to the present invention, since a user basically transmits a message using a commercial messenger service, various data such as photos, videos, documents, etc. can be attached to the message, and encryption processing for the attached file data is also performed. Since it can be processed in a form similar to the message content, not only message data but also security of attached data can be supported.

In addition, according to the present invention, high security is achieved by using the block chain characteristics to support message sender and receiver identity authentication, message content confidentiality and integrity, and message transmission/reception non-repudiation proof at the security level of the block chain. It has the advantage of being able to actively use it in fields such as the military or financial fields that require it.

1 is an overall configuration diagram of a blockchain-based secure messenger service system according to an embodiment of the present invention.
FIG. 2 is an exemplary diagram for explaining a function of a secure messenger corresponding to a messenger client of the block chain-based secure messenger service system of FIG. 1 .
3 is an exemplary diagram of a data structure that can be employed for a non-fungible token generated in the secure messenger of FIG. 2 .
FIG. 4 is an exemplary diagram for explaining the operation principle of the secure messenger service by the block chain-based secure messenger service system of FIG. 1 .
5 is a flowchart of a blockchain-based secure messenger service method according to an embodiment of the present invention.
6 and 7 are exemplary views illustrating an interface that can be employed in a user terminal of the secure messenger service method of FIG. 5 .

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

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

When an element is referred to as being “connected” or “connected” to another element, it is understood that it may be directly connected or connected to the other element, but other elements may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

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

Before describing a preferred embodiment of the present invention, the main terms are as follows.

Blockchain refers to a system in which nodes participating in a network maintain a decentralized transaction ledger. In other words, the block chain is a data structure in which a block composed of a set of transactions contains the hash value of the previous block and connects all blocks in a chain format. It is a distributed ledger technology that maintains the same data structure and creates and connects new blocks based on a consensus algorithm. Even if the blockchain data of a specific node is arbitrarily manipulated, data manipulation can be detected immediately because it has the hash value of the previous block between blocks, and the manipulated data is not reflected in the blockchain because it is not agreed upon between nodes. As such, blockchain guarantees data integrity and transparency because it is impossible to arbitrarily forge or falsify data.

Blockchain is divided into permissionless blockchain and permissioned blockchain. A permissionless blockchain is a blockchain that allows users and nodes to participate in a blockchain network without any restrictions. Representative unauthorized blockchains include Bitcoin and Ethereum. A permissioned blockchain is a blockchain suitable for use in a business environment where only authorized users and nodes can participate in the blockchain network. A representative permissioned blockchain is Hyperledger Fabric.

A smart contract refers to a contract that concludes and executes various types of contracts, such as notarization and real estate contracts, based on blockchain. It is possible to develop and operate a decentralized application (dApp) by configuring business logic through a smart contract. Smart contracts have the advantage of automatically executing requests according to business logic without the intervention of a third party. A representative dApp is a token.

A token is a digital asset expressed on a blockchain. Tokenizing digital assets on the blockchain can secure advantages such as proof of ownership of digital assets, transparency and liquidity guarantees. Tokens are divided into fungible tokens and non-fungible tokens. A fungible token is a token that expresses a digital asset that can be split, and a non-fungible token is a token that expresses a digital asset that cannot be split.

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

1 is an overall configuration diagram of a blockchain-based secure messenger service system according to an embodiment of the present invention.

Referring to FIG. 1 , the blockchain-based secure messenger service system includes a messenger sender terminal 100a, a messenger receiver terminal 100b, a centralized messenger server 200, and a block chain-based secure messenger service device 500. . Here, the centralized messenger server 200 supports a message transmission/reception function between the messenger transmitter terminal 100a and the messenger receiver terminal 100b through an external messenger service.

The messenger sender terminal 100a and the messenger receiver terminal 100b include a smart phone, a personal computer (PC), a personal mobile communication terminal, and the like, and are responsible for inputting messages and various types of attached data for transmission and reception. do. Message and attached data encryption can be processed by generating an encryption key on the terminal.

In addition, the messenger sender terminal 100a and the messenger receiver terminal 100b may be equipped with a messenger client that interworks with the centralized messenger server 200. In this case, the messenger client is a software module implementing a block chain-based secure messenger service device. It can be linked with a blockchain-based secure messenger service device or a software module that implements it.

Also, the messenger sender terminal 100a may select one of a general message and a secure message to transmit the message. In this case, the secure messenger 300 sends a message to the centralized messenger server 200 through the messenger API SDK 320 in the same manner as in the conventional messenger service when a general message transmission is desired according to the message type selected by the messenger sender terminal 100a. When sending a general message and sending a secure message, the blockchain SDK 310 in the secure messenger 300 sends a blockchain transaction to the blockchain 400 to generate a blockchain non-fungible token associated with the message. At the same time, the corresponding message may be transmitted to the centralized messenger server 200 through the messenger API SDK 320 .

The centralized messenger server 200 supports message transmission and reception services in an Internet environment. It may include messenger services that provide message sending/receiving service APIs, such as KakaoTalk, Line, and Telegram, which currently provide commercial services. In this case, the commercial messenger service may be regarded as a service independent of the contents of the secure messenger service of the present embodiment.

The block chain-based secure messenger service device 500 includes a secure messenger 300 and a block chain 400 . The secure messenger 300 is composed of a block chain software development kit (SDK) 310 in charge of linking with the block chain and the messenger API SDK 320 in charge of linking with the centralized messenger server 200 . The block chain-based secure messenger service device 500 provides a secure messenger service using the block chain according to the present embodiment.

As an example in which the block chain-based secure messenger service device 500 connects with the centralized messenger server 200, in FIG. 1, RESTful form collectively refers to web services that provide API (application programming interface) based on REST (Representational State Transfer). It expresses the connection with the API of

The messenger API SDK 320 of the secure messenger 300 processes message transmission by the messenger sender terminal 100a through the external centralized messenger server 200 . And, the blockchain SDK 310 creates or manages a blockchain-based non-fungible token. The secure messenger 300 supports the inquiry of non-fungible tokens through the block chain SDK 310 for message confirmation in the messenger receiver terminal 100b.

The block chain 400 can be any type of block chain, such as a permissioned or non-permitted block chain, and can be configured independently of the block chain-based secure messenger service of the block-chain-based secure messenger service device.

In the block chain 400, the node of the institution in charge of the content of the message may be composed of participating nodes, and it plays a role of managing the generated message token in a block. At this time, when the messenger server 200 is used for business purposes, it can be configured as a permissioned blockchain to limit participants in the blockchain network, and in other cases, it can also be configured as an unlicensed public blockchain.

FIG. 2 is an exemplary diagram for explaining a function of a secure messenger corresponding to a messenger client of the block chain-based secure messenger service system of FIG. 1 .

Referring to FIG. 2 , the secure messenger 300 of the block chain-based secure messenger service device according to the present embodiment includes a block chain SDK 310 and a messenger API SDK 320, and generates a block chain token per message; It manages messages by supporting functions such as transmission and search.

To this end, the blockchain SDK 310 includes a token issuance module 311, a token transmission module 312, a token modification module 313, a token inquiry module 314, and an event module 315 that receives events occurring on the block chain. ), the token verification module 316 is defined. And the messenger API SDK 320 defines an API module 321 that communicates with the centralized messenger server 200 .

The token issuance module 311 generates a transaction for issuing a message token and transmits the generated transaction to the block chain 400 . More specifically, when the messenger sender terminal 100a requests transmission of a secure message, the secure messenger 300 calls the token issuance module 311 to generate a block chain transaction, and a message token on the block chain 400 . to issue When the initial message token is issued, the entity that issued it becomes the owner of the token. The data structure of the blockchain token will be described in the detailed description below with reference to FIG. 3 .

The token transmission module 312 transmits a transaction for transmitting a message token to a specific target to the block chain 400 . More specifically, the messenger sender terminal 100a, which is the owner of the initial message token, contains information on the messenger receiver terminal 100b, calls the token transmission module 312, creates a transaction, and sends the message token to the messenger receiver terminal 100b. transfer ownership of That is, when the call to the token transmission module 312 is completed, the token owner is changed to the messenger receiver terminal 100b.

At this time, in the message token, the right to call the token transfer module 312 exists for the owner, the approver, and the operator, but in this embodiment, the role of the approved person and the operator is not used. have. However. In another embodiment of the present invention, call authority may be granted to an approved person or an operator.

The token modification module 313 creates a transaction that records the sub-attribute value of the extended attribute of the message token and transmits it to the blockchain 400 . More specifically, only the owner has the right to call the token modification module 313, but in the present embodiment, the messenger sender terminal 100a and the messenger receiver terminal 100b are connected to the token modification module 313 by the secure messenger 500. ) to be called.

When the messenger sender terminal 100a calls the token transmission module 313 to transmit a secure message to the messenger receiver terminal 100b, the messenger receiver terminal 100b calls the token modification module 313 to indicate that the secure message has been received. can be recorded in the token inquiry status attribute. Through this, the messenger transmitter/receiver terminals 100a and 100b can prove later that they have transmitted and received a secure message, respectively.

The token inquiry module 314 creates a transaction that inquires the properties of the message token and transmits it to the blockchain 400 . When the secure message is received, the messenger receiver terminal 100b calls the token inquiry module 314 to inquire the encryption symmetric key property of the message token transmitted by the messenger sender terminal 100a, and retrieves the security message with the inquired encryption symmetric key. You can read the contents of the message by decrypting it.

When the secure messenger 300 receives an event from the block chain 400 , the event management module 315 functions to send a notification to the calling subject. After the token issuance module 311, the token transmission module 312, and the token modification module 313 are called, when the operation result for the message token is finally stored in the block chain 400, the secure messenger 300 is a block chain An event may be received from 400 .

For example, when the messenger sender terminal 100a issues a message token on the blockchain 400 through the token issuance module 311, the event management module 315 sends a successful message token issuance to the messenger sender terminal 100a. inform

In addition, when the messenger sender terminal 100a transfers the ownership of the message token existing on the block chain 400 through the token transmission module 312, the event management module 315 calls the token transmission module 312. Inform the subject of a successful transfer of ownership.

In addition, when the messenger sender terminal 100a and the messenger receiver terminal 100b modify the sub-attribute value of the extended attribute of the message token through the token modification module 313, the event management module 315 returns the successful modification to the messenger. Successful modification may be notified to the transmitter/receiver terminals 100a and 100b.

The token verification module 316 is responsible for authenticating the identity of the user who has issued the non-fungible token. That is, it functions to provide a criterion for determining whether the user who issued the non-fungible token is the user who actually sent the message to him or her.

Since all users are registered on the blockchain after user identity is verified, transactions can be created based on their signature information. Therefore, the message token receiver calls the token verification module 316 to check the sender messenger ID recorded in the message token issued by the sender, and the user information and public key corresponding to the sender messenger ID are the sender's user information and public key By comparing whether it matches with , authentication of the sender's user identity is performed.

The API module 321 of the messenger API SDK 320 functions to communicate with the centralized messenger server 200 . When the sender successfully issues a message token through the secure messenger 300 , the encrypted message content is transmitted to the centralized messenger server 200 through the API module 321 . Finally, the centralized messenger server 200 that has received the secure message may transmit it to the receiver.

The secure messenger of the block chain-based secure messenger service device according to the present embodiment generates a non-fungible token generated on the block chain for an encrypted transmission message, that is, input message data, and the data structure of the generated non-fungible token is An example is shown in FIG. 3 .

FIG. 3 is an exemplary diagram of a data structure that can be employed for a non-fungible token generated in the secure messenger of FIG. 2 .

Referring to FIG. 3 , a data structure of a non-fungible token that is a message token 30 of input message data includes a standard attribute 32 and an extended attribute 34 . The standard attribute 32 includes a token identifier (id), a token type (type), an owner and an approvee, and the extended attribute 34 includes an on-chain extended attribute (xattr) and an off-chain extended attribute. , and define sender/receiver messenger ID, encryption symmetric key, validity period and token inquiry status as sub-properties of on-chain extended attribute (xattr), and define path and hash as off-chain extended sub-attributes.

In addition, the message token may be newly generated per transmission message or newly generated per sender/receiver message communication session. If each outgoing message contains important content, one message token is generated for each transmitted message. The overhead can be reduced by generating tokens. Although this embodiment describes an example as generating one message token per transmission message, a method of generating a message token per sender/receiver message communication session is also included in the scope of this embodiment.

In the sender/receiver messenger ID attribute, ID information of the centralized messenger of the sender and receiver can be input, respectively. In the encryption symmetric key attribute, a symmetric key obtained by encrypting the symmetric key used when the sender encrypts the content of the message transmitted by the receiver's public key can be entered. By entering the validity period of the token in the validity period attribute, the sender or receiver can finally determine the validity of the message regardless of the messenger server. Finally, after the receiver receives the token, he or she can input his or her signature information into the token inquiry status attribute when inquiring about the token.

According to the message token of this embodiment, token identifier (id), token type (type), owner and approver are set as standard properties of a message token that is a token type message (Message), and on-chain expansion Set the sender/receiver messenger ID, encryption symmetric key, validity period, and token inquiry status properties subscribed to the centralized messenger server 200 as sub-properties of the attribute (xattr), and set the path and hash properties as open chain extension sub-properties By setting this, it is possible to effectively provide user authentication according to message transmission/reception, message integrity verification, and non-repudiation of transmission/reception functions.

FIG. 4 is an exemplary diagram for explaining the operation principle of the secure messenger service by the block chain-based secure messenger service system of FIG. 1 .

The overall operation principle of the blockchain-based secure messenger service system according to the present embodiment is shown in FIG. 4 .

Referring to FIG. 4 , both the messenger transmitter/receiver terminals 100a and 100b and the centralized messenger server 200 are users registered in the block chain 400 , and authenticate the user identity during registration. In addition, the authenticated user is issued a PKI-based public key and a private key.

The messenger transmitter/receiver terminals 100a and 100b and the centralized messenger server 200 may be connected to the secure messenger service device 500 through a network. In this embodiment, the secure messenger service device 500 may include the secure messenger 300 and the block chain 400 in the macro aspect, and the secure messenger 300 in the micro aspect and connected to the block chain 400 . or can be linked.

The secure messenger 300 stores user information and public keys to control users who can access the block chain. Accordingly, the authorized user may perform user authentication through a blockchain-based non-fungible token using his/her public key managed by the secure messenger 300 .

When the messenger sender terminal 100a wants to transmit a secure message, a symmetric key is generated to encrypt the message content after inputting the message content, and the public key of the receiver is obtained through the secure messenger 300 .

In addition, when a secure message is to be transmitted, the message content is encrypted with the symmetric key generated by the sender, and the symmetric key encrypted with the message content is encrypted with the recipient's public key through the block chain SDK 310 of the secure messenger 300 to block It is recorded in the message token attribute of the chain 400 . Therefore, the message token of the block chain 400 can be accessed by a third party, but the recipient's private key is required to decrypt the encrypted message content.

Specifically, when the messenger sender terminal 100a transmits a secure message, the operation process of the blockchain-based secure messenger service 500 is as follows.

First, the messenger sender terminal 100a issues a message token (token id is T ₀ ) based on a secure messenger message on the block chain 400 by calling the token issuing module (S110). The message token is a sub-property of the extended attribute, and includes the ID of the messenger sender terminal 100a, the ID of the messenger receiver terminal 100b, symmetric key information encrypted with the receiver's public key, the validity period of the secure message, and the token inquiry status attribute. .

Next, the event management module of the secure messenger 300 notifies the messenger sender terminal 100a that the issuance of the message token T ₀ is completed, and the messenger sender terminal 100a sends the message receiver terminal 100b through the token transmission module. A message token (T ₀ ) is transmitted to (S120).

Next, the messenger sender terminal 100a, having received a notification of the success of the token transmission from the event management module of the secure messenger 300, transmits a secure message including the message token (T ₀ ) and the content of the transmitted message through the network to the centralized messenger server ( 200) (S210).

Next, the centralized messenger server 200 transmits the received secure message to the messenger receiver terminal 100b (S220).

Next, the messenger receiver terminal 100b calls the verification module 316 to verify the received secure message (S310). The messenger receiver terminal 100b verifies the message token issued based on the sender's signature to confirm the sender's identity. In other words, in order for a third party to disguise the identity of the sender and transmit a message, the message must be issued based on the sender's signature, making message transmission impossible. Therefore, the receiver checks the sender messenger ID recorded in the message token issued by the sender, and compares whether the user information and public key related to the sender messenger ID match the user information and public key of the sender known to the receiver, Sender identity authentication is performed.

In addition, to ensure the integrity of the message content, the message sender issues a non-fungible token based on the message content and registers it on the blockchain. Accordingly, the encrypted message content can be decrypted using the symmetric key stored in the message token, and accordingly, the message content can be checked in the messenger receiver terminal 100b (S320).

In addition, for the non-repudiation of message sending/receiving act, token is issued based on the signature information of the messenger sender terminal 100a, so it is possible to prove non-repudiation of the sending act. The message receiver terminal 100b receives the additionally issued message token, and calls the token modification module of the secure messenger 300 when inquiring the symmetric key recorded in the token to check the message content, indicating that the receiver has inquired the message token. In fact, it provides proof of non-repudiation of receipt by recording the recipient's signature information in the token inquiry status attribute of the message token.

According to this embodiment, the blockchain-based secure messenger service method and device can solve user identity authentication, message content integrity and confidentiality guarantee, and non-repudiation proof of sending/receiving actions through blockchain, especially by modeling non-fungible tokens You can have the messenger send or receive security-enhanced messages.

On the other hand, it has been described that the block chain-based secure messenger service device 500 according to the present embodiment is in the form of a separate device connected to the messenger transmitter/receiver terminals 100a and 100b and the centralized messenger server 200 through a network. , the present invention is not limited to such a configuration, and may have an installation structure in which the messenger sender terminal 100a and the messenger receiver terminal 100b are respectively installed in the form of an application application.

5 is a flowchart of a blockchain-based secure messenger service method according to an embodiment of the present invention.

In this embodiment, the first user terminal 100A corresponding to the sender of the specific message includes the first secure messenger 300a, and the second user terminal 100B corresponding to the receiver of the specific message is the second security message. A messenger 300b is provided. The secure messenger may correspond to a messenger client interworking with a centralized messenger server.

The first secure messenger 300a and the second secure messenger 300b may each include the blockchain SDK and the messenger API SDK described above with reference to FIG. 2 . The blockchain SDK may include a token issuance module, a token transmission module, a token modification module, a token inquiry module, an event management module, and a token verification module, and the messenger API SDK may include an API module.

Referring to FIG. 5 , when there is a first user and a second user communicating through a message of a messenger service on a network, the first user terminal 100A sends a message using the recipient public key through the first secure messenger 300a. is encrypted (S51), and the encrypted message is transmitted to the second user terminal 100B through the centralized messenger server 200 (S52, S53). At this time, the messenger server 200 cannot view the contents of the encrypted message because there is no symmetric key for decryption.

Next, as the encrypted message, that is, the secure message is transmitted from the first user terminal 100A to the second user terminal 100B, the first secure messenger 300a obtains input message data (S54). The input message data may include an encrypted message previously sent from the first user terminal 100A to the second user terminal 100B or a unique identifier related thereto.

Next, the first secure messenger 300a issues a message token based on the input message data on the block chain. For example, the first secure messenger 300a transmits a message token issuance request signal for issuing a message token based on the input message data to the block chain 400 (S55) and issues a message token in response to the message token issuance request signal. A message token may be received from the block chain 400 (S56, S57).

Next, the first secure messenger 300a changes the owner of the message token to the second user terminal 100B (S58). Then, the owner transmits the changed message token to the second user terminal 100B (S59).

On the other hand, the second secure messenger 300b of the second user terminal 100B that has received the previously encrypted message decodes the message token in response to the receipt of the message token (S61), and uses the token ID obtained through decoding ( 400), the token may be inquired (S620), and the identity of the sender may be verified (S63).

On the other hand, regardless of before or after reception of the message token, when receiving the encrypted message, the second user terminal 100B may decrypt the message with the symmetric key it owns to check the message content. In this case, the symmetric key refers to a key paired with the public key used to encrypt the encrypted message.

As described above, according to the configuration of the present embodiment, it is possible to effectively secure the messages of users in a commercial messenger service through a secure messenger, which is an application application mounted on the processor of the user terminal, so that a secret or private conversation is possible.

On the other hand, the block chain 400 that can be employed in the secure messenger service method or device of the above-described embodiment may include a chaincode or permission-type block chain system that supports non-fungible tokens, and also the block chain ( 400) may include a peer server that generates a non-fungible token for an object having uniqueness on a block chain using a smart contract. In this case, when the issuance of a non-fungible token for a specific object is requested through a decentralized application (dApp), the peer server calls the token issuance function through the token management unit to include the token identifier, token type, and owner. It is possible to issue a non-fungible token having a data structure composed of basic properties and extended properties set for each token type, and record the current state of the issued non-fungible token in the database.

Here, the non-fungible token may correspond to the message token. If the non-fungible token is an open blockchain such as Ethereum, the non-fungible token has a standard data structure and an extensible data structure, and standards such as ERC-721 and default It may include an interface and an extension interface. In addition, the framework of the secure messenger service device for the non-fungible token may include a standard protocol and an extension protocol for communication with the dApp. Here, the standard protocol may be composed of an ERC-721 protocol and a default protocol. The ERC-721 protocol is defined to provide an Ethereum ERC-721 token standard interface in a fabric environment, and the default protocol defines functions for properties defined in the standard data structure. And the extension protocol defines getter and setter functions for xattr and uri that manage the extended data structure.

In this case, the function defined in the protocol cannot directly access the property in the data structure, but may be implemented to access it through the property management function. For example, an on-chain extended data structure can be implemented with the IType interface and the Adapter design pattern. Property management functions for xattr sub-properties are defined in the IType interface. When type 1 is added, xattr sub-properties are defined in the type 1 class, and property management functions can be implemented by inheriting the IType interface. And type 1 can be registered in the XAttrAdapter class so that different xattr sub-properties can be specified according to the token type through the Adapter design pattern.

In addition, the first secure messenger 300a or the second secure messenger 300b that can be employed in the above-described secure messenger service method is a form in which a security function is added to existing commercial messenger services such as KakaoTalk, Line, and Telegram. may be implemented, but is not limited thereto, and may be implemented in the form of a separate messenger function extension application application coupled to an existing commercial messenger service, or separately implemented in the form of a messenger application application having the security function of the present embodiment. .

6 and 7 are exemplary views illustrating an interface that can be employed in a user terminal implementing the secure messenger service method of FIG. 5 .

Referring to FIG. 6 , the user terminal 100A equipped with a secure messenger performs a series of operations such as encryption of a single message or group message selected on the messenger screen 110 , transmission of an encrypted message, issuance of a message token, transmission of a message token, etc. A user interface for instructing execution of a secure messenger operation may be provided. This user interface includes a message sending user interface that selects between sending a non-secure message and sending a secure message. In this embodiment, the message transmission user interface has the form of a button 120 marked as 'security' at the bottom of the messenger screen 110, but is not limited thereto, and various user input types such as images, voices, and vibrations are single or combined. can be used as

In addition, as shown in FIG. 7 , the user terminal 100A that can be employed in the secure messenger service method or apparatus according to the present embodiment includes a text file, a document file, an image file, an image file, and a voice transmitted during the messenger service. For an attached file including a file, similarly to the method described with reference to FIG. 5 and the like, the attached file is encrypted and transmitted to the user terminal of the receiver side, the input attachment data for the encrypted attached file is obtained, and input A user interface for instructing execution of a series of secure messenger operations, such as issuing a blockchain-based non-fungible additional token for the attachment data, and transmitting the non-fungible additional token to the user terminal of the recipient side, may be provided. Such a user interface has a button 130 displayed as 'attached security' at the top of the messenger screen 110 of FIG. 7, but is not limited thereto.

In addition, although not shown in the drawing, when a user terminal equipped with a secure messenger receives an encrypted message or a message token, the encrypted message displayed with buttons such as 'security release' and 'decoding' on the messenger screen A user interface for decoding or a user interface for decoding a message token may be provided.

Meanwhile, the operation of the secure messenger service method according to the above-described embodiment may be implemented as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored. In addition, the computer-readable recording medium may include a storage or database in which a computer-readable program or code can be stored and executed in a distributed manner by being distributed in a networked computer system.

In addition, the computer-readable recording medium may include a hardware device specially configured to store and execute program instructions, such as ROM, RAM, and flash memory. The program instructions may 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.

In addition, at least a part of a series of procedures of the secure messenger service method according to the present embodiment may be implemented by, for example, a hardware device such as a microprocessor, a programmable computer, or an electronic circuit or using a hardware device. Also, a programmable logic device, such as a field programmable gate array, may be used to perform some or all of the functions of the methods described herein. In embodiments, the field programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described herein. In general, the methods are preferably performed by some hardware device.

Although described above with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention as set forth in the following claims. will be able to understand

Claims (20)

A blockchain-based secure messenger service method executed by a first user terminal of a sender, comprising:
encrypting a message or an attached file to be transmitted to a second user terminal of the recipient;
transmitting the message encrypted in the encrypting step to the second user terminal through a centralized messenger server;
issuing a blockchain-based non-fungible token corresponding to the encrypted message; and
transmitting the non-fungible token to the second user terminal;
A blockchain-based secure messenger service method comprising a. The method according to claim 1,
The encrypting includes encrypting the message or the attached file using the public key of the recipient, a block chain-based secure messenger service method. The method according to claim 1,
Further comprising the step of changing the owner of the non-fungible token to the recipient after the step of issuing, a blockchain-based secure messenger service method. The method according to claim 1,
The first user terminal and the second user terminal hold a public key-based (Public Key Infrastructure) key pair authenticated by a certificate authority, a block chain-based secure messenger service method. The method according to claim 1,
The properties of the non-fungible token include a token identifier (ID), token type, owner information, sender messenger ID, receiver messenger ID, message content encryption symmetric key information, validity period and token inquiry status information, a blockchain-based secure messenger service method. The method according to claim 1,
The non-fungible token includes a token attribute for token generation and transmission transaction processing information, wherein the sender or the receiver non-repudiation as to whether the message has been sent or received through the token generation and transmission transaction processing information A blockchain-based secure messenger service method to obtain proof. The method according to claim 1,
The non-fungible token includes a token attribute for an validity period, wherein the sender or the receiver self-determines message validity through the validity period. The method according to claim 1,
The first user terminal and the second user terminal are messenger clients that transmit and receive signals and data through the centralized messenger server, and use the Extensible Messaging and Presence Protocol (XMPP) or the messenger's own protocol, a blockchain-based secure messenger. service method. The method according to claim 1,
The sender verifies the recipient's non-repudiation of receipt through the token inquiry status attribute of the non-fungible token;
The receiver verifies the identity of the sender by checking the sender signature and messenger ID recorded in the non-fungible token by inquiring the non-fungible token, or encrypted through a message encryption symmetric key corresponding to the public key of the recipient. A blockchain-based secure messenger service method that decrypts messages. The method according to claim 1,
The method further comprising: obtaining a user input or command from a user interface for selecting transmission of a non-secure message and transmission of a secure message from the first user terminal or the second user terminal, wherein the message is encrypted according to the user input or command A block chain-based secure messenger service method in which a series of processes including steps, transmitting the encrypted message, issuing the message token, and transmitting the message token are performed. The method according to claim 1,
Attached files of photos, videos, document data, or a combination thereof included in the message are stored in an off-chain space accessible through a network, and the non-fungible token records the storage path of the off-chain space for the attachment. , Blockchain-based secure messenger service method. 12. The method of claim 11,
Obtaining the encrypted attachment data of the attachment on the messenger screen of the first user terminal, issuing a blockchain-based non-fungible additional token for the encrypted attachment data, and applying the non-fungible additional token to the second A block chain-based secure messenger service method further comprising the step of providing a user interface for transmission to a user terminal. A block chain-based secure messenger service device mounted on a first user terminal of a sender, comprising:
a message processing unit for transmitting a message to be transmitted to a second user terminal of a recipient or an encrypted message of an attached file to the second user terminal through a centralized messenger server; and
a token processing unit that acquires input message data for the encrypted message, issues a blockchain-based non-fungible token for the input message data, and transmits the non-fungible token to the second user terminal;
A blockchain-based secure messenger service device comprising a. The method according to claim 13, The token processing unit,
a token issuance module for obtaining input message data for the encrypted message and issuing a blockchain-based non-fungible token for the input message data;
a token transmission module for transmitting the non-fungible token to the second user terminal; and
a token modification module for changing the owner of the non-fungible token to the recipient;
A block chain-based secure messenger service device comprising a. 14. The method of claim 13,
The block chain-based secure messenger service device further comprising a token inquiry module that generates a transaction for inquiring the properties of the message token and transmits the generated transaction to a block chain to inquire an encryption symmetric key of the message token. 14. The method of claim 13,
Blockchain-based security further comprising an event management module that receives an event from the block chain when the operation result for the message token by the token issuance module, the token transmission module, and the token modification module is finally stored in the block chain messenger service device. 14. The method of claim 13,
The token processing unit calls a token verification module to check the counterpart's messenger ID recorded in the message token, and compares the user information and public key corresponding to the counterpart's messenger ID with the counterpart's user information and public key. , a blockchain-based secure messenger service device that authenticates the user identity of the other party. 14. The method of claim 13,
The first user terminal or the second user terminal holds a public key infrastructure (Public Key Infrastructure) key pair authenticated by a certificate authority, a block chain-based secure messenger service device. 14. The method of claim 13,
The properties of the non-fungible token include a token identifier (ID), token type, owner information, sender messenger ID, receiver messenger ID, message content encryption symmetric key information, validity period and token inquiry status information, a blockchain-based secure messenger service device. 14. The method of claim 13,
The secure messenger including the messenger processing unit and the token processing unit selects non-secure message transmission and secure message transmission according to a specific input or command in a user interface provided on a messenger service screen of a user terminal, a block chain-based secure messenger service device .

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