Ford, BryanGasser, LinusKokoris Kogias, EleftheriosJanovic, Philipp2019-12-052019-12-052019-12-052019https://infoscience.epfl.ch/handle/20.500.14299/163737The present invention concerns a computer-implemented method for secure data exchange between a sender (A) and a recipient (B), wherein the method is performed by the sender (A) and comprises encrypting data using a symmetric key k, creating a write transaction T W , wherein the write transaction T W comprises information usable to derive the symmetric key k and an access policy identifying the recipient (B) as being allowed to decrypt the encrypted data, providing the recipient (B) access to the encrypted data, and sending the write transaction T W to a first group of servers (AC) for being stored in a blockchain data structure maintained by the first group of servers (AC).patentUS2021089676WO201915820961231277