A computer-implemented system for secure storage and transfer of digital data between users of a network for data sharing, comprising: (a) a plurality of users' computing devices for access to a network for data sharing; (b) a digital identity associated to each user of the network and comprising an authentication means, said authentication means comprising a processor capable of automatically generating an authentication code in response to an interrogation for validating the digital identity of a user, wherein a new authentication code is generated in response to each new interrogation; (c) at least one certificatory entity in communication with the authentication means and computing devices of the system, and comprising a processor capable of validating a user's digital identity by interrogating the authentication means and verifying the authentication code generated by the authentication means in response to the interrogation, and configured to issue an electronic certificate to the computing devices of validated users whose digital identity is validated; (d) at least one transaction involving two or more users, authorized by validation of said two or more users' digital identities by the at least one certificatory entity, each transaction comprising digital information that is generated, owned and/or shared by at least one of said two or more validated users; (e) at least one digital repository having a digital address and storing at least part of the digital information of an authorized transaction, said digital repository comprising a gateway configured to share the digital information only with the computing devices of one or more of the validated users involved in the transaction; characterized in that it further comprises: (f) a personal ledger database associated to each user of the network, stored in or in communication with the users' computing device, each personal ledger database comprising blocks linked by a cryptographic key, and being structured so that, when a transaction between two or more validated users is authorized, a new block is added to the personal databases associated to each of said two or more validated users, wherein said new block records the digital addresses of the at least one digital repository storing at least part of the digital information of said transaction. (a) a plurality of users' computing devices for access to a network for data sharing; (b) a digital identity associated to each user of the network and comprising an authentication means, said authentication means comprising a processor capable of automatically generating an authentication code in response to an interrogation for validating the digital identity of a user, wherein a new authentication code is generated in response to each new interrogation; (c) at least one certificatory entity in communication with the authentication means and computing devices of the system, and comprising a processor capable of validating a user's digital identity by interrogating the authentication means and verifying the authentication code generated by the authentication means in response to the interrogation, and configured to issue an electronic certificate to the computing devices of validated users whose digital identity is validated; (d) at least one transaction involving two or more users, authorized by validation of said two or more users' digital identities by the at least one certificatory entity, each transaction comprising digital information that is generated, owned and/or shared by at least one of said two or more validated users; (e) at least one digital repository having a digital address and storing at least part of the digital information of an authorized transaction, said digital repository comprising a gateway configured to share the digital information only with the computing devices of one or more of the validated users involved in the transaction;