System and method for providing a collective decentralized authority for sharing sensitive data

A method of sharing private and/or sensitive data from plurality of data providers to a data user, the data user having a private key and a public key, the method comprising the steps of providing a first data set and encrypting the first data set at a terminal of a first data provider with a collective public key, providing a second data set and encrypting the second data set at a terminal of a second data provider with the collective public key, sending the encrypted data to a server from the plurality of servers, the plurality of servers forming together a collective and decentralized authority, decentralized aggregating the encrypted data of the first and second data providers by the plurality of servers, based on the homomorphic encryption scheme, to compute a first encrypted aggregated data set, modifying the encryption of the first encrypted aggregated data set from the encryption based on the collective public key to an encryption based on the public key of the data user to generate a second encrypted aggregated data set.