A computer-implemented method for sharing data associated with a first user, the method comprising: storing, at a first system, user data associated with the first user; storing, at the first system, a first authorised entity database comprising a plurality of authorised entity labels each indicative of an identifier of an authorised entity, wherein storing the first authorised entity database comprises: transmitting, from the first system to an authorisation system, a plurality of requests to access a second authorised entity database stored at the authorisation system; and receiving and storing, at the first system, at least a portion of the second authorised entity database in response to each one of the plurality of requests to access an authorised entity database; wherein the plurality of requests to access the second authorised entity database are transmitted in a predefined time sequence, wherein the predefined time sequence comprises a predefined time interval between each adjacent one of the requests to access the second authorised entity database, and wherein the predefined time sequence is configured by the first system, based on system conditions storing, at the first system, an unauthorised entity database comprising a plurality of unauthorised entity labels each indicative of an identifier of an unauthorised entity; receiving a first access message, from a second system, associated with a request for access to the user data stored at the first system, the first access message comprising a second system label indicative of an identifier of the second system; in response to receiving the first access message, comparing the second system label with the plurality of authorised entity labels and the plurality of unauthorised entity labels stored at the first system; in response to identifying that the second system label matches an authorised entity label and that the second system label does not match an unauthorised entity label, transmitting a grant message indicative that the request for access is granted; and preventing transmission of the grant message, if the second system label in the first access message matches an unauthorised entity label and/or does not match an authorised entity label. storing, at a first system, user data associated with the first user; storing, at the first system, a first authorised entity database comprising a plurality of authorised entity labels each indicative of an identifier of an authorised entity, wherein storing the first authorised entity database comprises: transmitting, from the first system to an authorisation system, a plurality of requests to access a second authorised entity database stored at the authorisation system; and receiving and storing, at the first system, at least a portion of the second authorised entity database in response to each one of the plurality of requests to access an authorised entity database; wherein the plurality of requests to access the second authorised entity database are transmitted in a predefined time sequence, wherein the predefined time sequence comprises a predefined time interval between each adjacent one of the requests to access the second authorised entity database, and wherein the predefined time sequence is configured by the first system, based on system conditions transmitting, from the first system to an authorisation system, a plurality of requests to access a second authorised entity database stored at the authorisation system; and receiving and storing, at the first system, at least a portion of the second authorised entity database in response to each one of the plurality of requests to access an authorised entity database; wherein the plurality of requests to access the second authorised entity database are transmitted in a predefined time sequence, wherein the predefined time sequence comprises a predefined time interval between each adjacent one of the requests to access the second authorised entity database, and wherein the predefined time sequence is configured by the first system, based on system conditions storing, at the first system, an unauthorised entity database comprising a plurality of unauthorised entity labels each indicative of an identifier of an unauthorised entity; receiving a first access message, from a second system, associated with a request for access to the user data stored at the first system, the first access message comprising a second system label indicative of an identifier of the second system; in response to receiving the first access message, comparing the second system label with the plurality of authorised entity labels and the plurality of unauthorised entity labels stored at the first system; in response to identifying that the second system label matches an authorised entity label and that the second system label does not match an unauthorised entity label, transmitting a grant message indicative that the request for access is granted; and preventing transmission of the grant message, if the second system label in the first access message matches an unauthorised entity label and/or does not match an authorised entity label.