Kryptosafe: managing and trading data sets using blockchain and IPFS.

Trading data sets is not easy. The owner of valuable data, once they are sold the first time, cannot be sure that they will not be copied and resold. On the other hand, the buyer, cannot be sure that the seller will not sell the same data to a competitor. The advent of blockchain technology, or DLT, can mitigate, or event solve these issues, because it can certify the data ownership, and act as a broker between seller and buyer. In this paper we present Kryptosafe, a system developed following sound software engineering practices, aimed to manage the trade of data sets taking advantage of the unique features of immutability and trustfulness of Ethereum blockchain, and of IPFS distributed DBMS. Kryptosafe allows data sellers to sell a whole encrypted data set or to show potential buyers a subset of it, allowing full access only after the sale is finalized. Using ERC721 and ERC1155 tokens, it also manages one-time sales, when the data set ownership is simply transferred to the buyer, or multiple sales of the same data set to different buyers.