Method to control the access of personal data of a user (UT1, UT2) by a trusted centre comprising at least one database comprising for a specific user, memory locations for personal data, access conditions associated to the personal data, and management data, - loading by a user into the database of the trusted center, its personal data and assigning access conditions to said data, said personal data being divided into at least two categories having two different access conditions, each category being associated with a user's value, - requesting access to the trusted centre by a third party (TPWS) to the personal data of a plurality of users, said request comprising search criteria, characterized in that, the management data further comprises at least a counter, and in case that the third party has not indicated a third party value: - executing by the trusted center the search criteria on the personal data of the users so as to determine a first set of users matching the search criteria, - returning to the third party (TPWS) information showing the quantity of the first set of users matching the criteria, as well as the sum of the user's value of each user of the first set, - acknowledging all of part of the sum by the third party, thus defining a second set of users that can comprise all or part of the first set, - returning the personal data of the second set of users for which the sum covers the accumulated values of the extracted users, Otherwise: - said request further comprises the third party value, - executing by the trusted center the search criteria on the personal data of the users so as to determine a second set of users matching the search criteria for which the user's value is equal or lower than the third party value, - returning the personal data of the second set of users, and - updating the counter of the second set of users with the content of the value of their respective personal data. - loading by a user into the database of the trusted center, its personal data and assigning access conditions to said data, said personal data being divided into at least two categories having two different access conditions, each category being associated with a user's value, - requesting access to the trusted centre by a third party (TPWS) to the personal data of a plurality of users, said request comprising search criteria, - executing by the trusted center the search criteria on the personal data of the users so as to determine a first set of users matching the search criteria, - returning to the third party (TPWS) information showing the quantity of the first set of users matching the criteria, as well as the sum of the user's value of each user of the first set, - acknowledging all of part of the sum by the third party, thus defining a second set of users that can comprise all or part of the first set, - returning the personal data of the second set of users for which the sum covers the accumulated values of the extracted users, - said request further comprises the third party value, - executing by the trusted center the search criteria on the personal data of the users so as to determine a second set of users matching the search criteria for which the user's value is equal or lower than the third party value, - returning the personal data of the second set of users, - updating the counter of the second set of users with the content of the value of their respective personal data.