Electronic device and method for providing secret messenger function through end-to-end encryption on basis of blockchain did technology

1 . A client device comprising:

a communication interface configured to communicate with an agency server and a counterpart device;

a memory; and

at least one processor operably connected to the memory and configured to execute instructions;

wherein the at least one processor is configured to:

transmit a topic creation request to the agency server,

when a topic creation notification is received from the agency server, generate a first subscription Decentralized Identifiers (DID) corresponding to the topic, a pair of first subscription private key and first subscription public key corresponding to the first subscription DID,

transmit the first subscription DID to the counterpart device,

receive a second subscription DID generated by the counterpart device from the agency server,

generate a first encryption key based on the first subscription private key and the second subscription DID, and

transmit message data encrypted with the first encryption key to the agency server.

2 . The client device of claim 1 , wherein the at least one processor is configured to:

generate a message block including the encrypted message data and a hash value of a previous message block, and

transmit the message block to the agency server.

3 . The client device of claim 1 , wherein the at least one processor is configured to:

generate a first account DID corresponding to the client device, a pair of account private key and account public key corresponding to the first account DID,

transmit the first account DID to the agency server, and

receive an address of a cloud DID agent corresponding to the first account DID from the agency server,

wherein the topic is included in the cloud DID agent.

4 . The client device of claim 3 , wherein

the topic creation notification includes a topic ID which is generated by the agency server and corresponds to the topic, and

wherein the at least one processor is configured to:

transmit the first account DID, the topic ID, and the first subscription DID to the counterpart device, and

transmit the encrypted message data to the topic created in the cloud DID agent through the address of the cloud DID agent and the topic ID.

5 . The client device of claim 4 , wherein the address of the cloud DID agent is stored in a blockchain network corresponding to the first account DID.

6 . The client device of claim 3 , wherein the at least one processor is configured to:

obtain a second subscription public key stored in mapping with the second subscription DID from the blockchain network based on the second subscription DID, and

generate the first encryption key based on the obtained second subscription public key and the first subscription private key.

7 . A method for providing messenger service, comprising:

transmitting, by a first client, a topic creation request to an agency server;

creating, by the agency server, a topic in a memory of the agency server in response to the topic creation request;

generating, by the first client, a first subscription DID corresponding to the topic and a pair of first subscription private key and first subscription public key corresponding to the first subscription DID, and transmitting the first subscription DID to a second client;

generating, by the second client, a second subscription DID corresponding to the topic and a pair of second subscription private key and second subscription public key corresponding to the second subscription DID, and transmitting the second subscription DID to the agency server;

transmitting, by the agency server, the second subscription DID to the first client;

transmitting, by the first client, message data encrypted with a first encryption key generated based on the first subscription private key and the second subscription DID to the agency server;

transmitting, by the agency server, the encrypted message data to the second client; and

decrypting, by the second client, the encrypted message data with the first encryption key generated based on the second subscription private key and the first subscription DID.

8 . The method of claim 7 , further comprising:

generating, by the first client, a first account DID corresponding to the first client and a pair of first account private key and first account public key corresponding to the first account DID;

transmitting, by the first client, the first account DID to the agency server;

generating, by the agency server, a cloud DID agent corresponding to the first account DID; and

receiving, by the first client, a cloud DID agent address corresponding to the first account DID from the agency server;

wherein the creating of the topic by the agency server comprises: creating, by the agency server, the topic within the cloud DID agent in response to the topic creation request.

9 . The method of claim 8 , further comprising:

transmitting, by the first client, a deletion request for the topic including a digital signature based on the first account private key to the cloud DID agent;

verifying, by the agency server, the digital signature through a blockchain network;

deleting, by the agency server, the topic stored in the cloud DID agent in response to the deletion request when the digital signature is confirmed to be a valid digital signature generated by the first client.

10 . The method of claim 7 , further comprising:

storing, by the agency server, the encrypted message in the topic; and

displaying, by the second client, the decrypted message through a display of the second client.

11 . The method of claim 7 , further comprising:

generating, by the first client, a message block including the encrypted message data and a hash value of a previous message block, and transmitting the message block to the agency server;

transmitting, by the agency server, the message block to the second client; and

determining, by the second client, whether the hash value of the previous message block stored in the message block is identical to a hash value of a previous message block previously stored in the second client.

12 . The method of claim 11 , further comprising:

transmitting, by the second client, a hash value mismatch alarm to the first client through the agency server when the hash value of the previous message block stored in the message block is not identical to the hash value of the previous message block previously stored in the second client.

13 . The method of claim 7 , wherein generating the first encryption key by the first client using the first subscription private key and the second subscription DID comprises:

obtaining, by the first client, a second subscription public key stored in mapping with the second subscription DID from the blockchain network based on the second subscription DID; and

generating, by the first client, the first encryption key based on the obtained second subscription public key and the first subscription private key.