A two-dimensional sharding model for access control and data privilege management of blockchain

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This paper presents a method to manage private data stored on a blockchain. With our method, the blockchain’s features for log transparency and tamper-resistance are maintained, even though the data is only available to authorized users. The most relevant work so far randomly selects nodes to store the decryption key shares of a threshold cryptosystem for some data which are not maintained in the system. They provide the decryption keys to the data requester via on-chain methods. This is for guaranteeing the availability and distributing the incentives. If the system maintains the data and wants to achieve the same guarantees, it has to post the data to the blockchain. This will make the blockchain oversized and the work impractical. This paper shows that nodes in our method may provide data to the requester directly without posing to the blockchain while guaranteeing availability and that the incentives be fairly distributed. Furthermore, each data request incurs a tiny size of transactions. We achieve so by implementing a two-dimensional sharding model, where nodes are randomly assigned to shards. Data is arithmetically compressed and then split into pieces. Each data piece is stored by a node in a first dimension shard. Without getting all the pieces, the data cannot be successfully decompressed. Each node in the first dimension shard is monitored by a second dimension shard. We propose designs that empower the corresponding second dimension shard for evaluating whether the first dimension node has provided the correct data piece to the data requester. This waives the need for placing the data into transactions and being witnessed by all. In case when a first dimension node fails, its data will be recovered by the corresponding second dimension shard.
Original languageEnglish
Article number102678
JournalSimulation Modelling Practice and Theory
Publication statusPublished - 2023

ID: 325821666