Index server, user terminal, and method of indexing blockchain transaction data

A user terminal, comprising:

• a communication module configured to establish a communication channel to an index server which manages an index database (DB) for indexing of transaction data stored in a blockchain network;
• and
• a processor,
• wherein the index DB indexes two-dimensional (2D) location data included in the transaction data as a K-d-B tree, constructs partial Merkle trees for a group of leaf nodes in the K-d-B tree, and provides hierarchical hash information of the K-d-B tree on the basis of the partial Merkle trees in connection with each of nodes in the K-d-B tree, and
• the processor transmits a query related to the location data via the communication module,
• receives a query result and verification data which is provided by the index server as a result of searching the K-d-B tree for the query result wherein verification data includes the hierarchical hash information and construction-related information of the partial Merkle trees;
• and the query result includes searched leaf node;
• calculates root hash information of the K-d-B tree related to a searched leaf node using construction-related information and the hierarchical hash information, and
• verifies integrity of the query result on the basis of the calculated root hash information.

A method of indexing blockchain transaction data by an index server, the method comprising:

• indexing two-dimensional (2D) location data in transaction data stored in a blockchain network in block units as a K-d-B tree;
• constructing partial Merkle trees for a group of leaf nodes in the K-d-B tree and storing hierarchical hash information based on the partial Merkle trees in each of nodes of the K-d-B tree;
• when a query related to the location data is acquired from a user terminal, searching the K-d-B tree to search a query result corresponding to the acquired query;
• generating verification data for verifying the searched query result on the basis of the partial Merkle trees and the hierarchical hash information;
• and
• providing the query result and the verification data to the user terminal to verify integrity of the query result using the partial Merkle trees and the hierarchical hash information by the user terminal.