Abstract: A blockchain based data management method performed by a computing device according to an embodiment of the present disclosure includes recording a deletion event for off-chain data and time information of the deletion event in a blockchain network, and selectively deleting the off-chain data based on a validity verification result calculated for the time information, wherein the validity verification result is calculated using a time-consensus algorithm of the blockchain network.

Abstract: A blockchain data recording method includes determining a recording type as one of an on-chain type and an off-chain type according to a target data to be recorded in a blockchain, transmitting a first transaction proposal for recording the target data in a blockchain node configured to store an on-chain data on a blockchain to the blockchain node when the recording type is an on-chain type, and recording the target data in a storage node provided to store an off-chain data, and transmitting a second transaction proposal for storing recording information of the target data in the blockchain to the blockchain node when the recording type is an off-chain type.

Abstract: A data management system according to an embodiment of this invention includes a blockchain node configured to store on-chain data on blockchain and a service server, upon receiving a service request associated with the original data from a client, i) accessing off-chain data stored in a storage node or recording off-chain data in the storage node according to the service request, and ii) sending a transaction proposal to the blockchain node for a record associated with the service request to be stored in the blockchain.

Abstract: An apparatus for guaranteeing the integrity of a state database includes a memory for storing one or more instructions, a communication interface for communicating with one or more blockchain nodes and a processor. The processor is configured, by executing the stored one or more instructions, to receive a request to query for a state value, obtain a first state value by querying a state database in response to the request, forward the request to the one or more blockchain nodes to receive a second state value from the one or more blockchain nodes and compare the first state value with the second state value to determine integrity of a state value.

Abstract: A blockchain based data management method performed by a computing device according to an embodiment of the present disclosure includes recording a deletion event for off-chain data and time information of the deletion event in a blockchain network, and selectively deleting the off-chain data based on a validity verification result calculated for the time information, wherein the validity verification result is calculated using a time-consensus algorithm of the blockchain network.

Abstract: A blockchain data recording method includes determining a recording type as one of an on-chain type and an off-chain type according to a target data to be recorded in a blockchain, transmitting a first transaction proposal for recording the target data in a blockchain node configured to store an on-chain data on a blockchain to the blockchain node when the recording type is an on-chain type, and recording the target data in a storage node provided to store an off-chain data, and transmitting a second transaction proposal for storing recording information of the target data in the blockchain to the blockchain node when the recording type is an off-chain type.

Abstract: A data management system according to an embodiment of this invention includes a blockchain node configured to store on-chain data on blockchain and a service server, upon receiving a service request associated with the original data from a client, i) accessing off-chain data stored in a storage node or recording off-chain data in the storage node according to the service request, and ii) sending a transaction proposal to the blockchain node for a record associated with the service request to be stored in the blockchain

Abstract: An apparatus for guaranteeing the integrity of a state database includes a memory for storing one or more instructions, a communication interface for communicating with one or more blockchain nodes and a processor. The processor is configured, by executing the stored one or more instructions, to receive a request to query for a state value, obtain a first state value by querying a state database in response to the request, forward the request to the one or more blockchain nodes to receive a second state value from the one or more blockchain nodes and compare the first state value with the second state value to determine integrity of a state value.

Abstract: Provided are a nonvolatile semiconductor memory device including ferroelectric semiconductor patterns in respective memory cells and methods of writing and reading data. The device includes a substrate; a plurality of first conductive lines disposed in or on the substrate; a plurality of second conductive lines disposed in or on the substrate and having a different height from the first conductive lines, wherein the second conductive lines intersect the first conductive lines, respectively, to define a plurality of intersection regions; and a plurality of memory cells disposed on the substrate. Herein, the memory cells include ferroelectric semiconductor patterns, respectively, which are disposed between the first conductive lines and the second conductive lines that define the intersection regions.