Method for controlling access to data sets (106, 108, 110, 112, 114, 116), comprising the steps of: - linking a first owner certificate (128, 130), which is assigned to a payload database, to a first user, wherein an owner certificate is a certificate that is assigned to one or more payload databases and each user to whom it is linked has the right to enter data sets in this payload database; - providing a first interface, which allows the first user to create a second owner certificate for the payload database and to link this certificate to a second user in order to allow said second user to enter data sets in the payload database; - providing a second interface, which allows the second user, who has created a data set (106, 108) in the payload database, to create at least one access certificate (Z.Zert_U2, Z.Zert_U2, Z.Zert_U2), which specifies a type of data set access to the data set created by the second user, and to link it to the user certificate of a user who is to be granted access to this data set, wherein the linking of the at least one access certificate to the generated data set is performed such that the at least one access certificate of the user who has created the data set is stored as part of the data set in a dedicated field of the payload database, wherein the at least one access certificate contains a plurality of access certificates (Z.Zert_U2, Z.Zert_U2, Z.Zert_U2) for other certificate types; - for each of the access types, generating an index structure from the access certificates of all data sets which specifies this access type, - in response to a database query of a user accessing one or more of the indices of the access certificates created for the payload database, verifying whether the user is allocated an index access certificate (Z.Zert_U2) which allows a user knowledge of the existence of the data set in the payload database and read access to metadata of the dataset, and allowing the use of the one or more indices to carry out the database query only if the user is allocated the index access certificate; - verifying the access authorisation of the first user to a data set entered by the second user, wherein the payload database grants the access only if the first user is assigned both an owner certificate for the payload database and an access certificate for the access to the data set. - linking a first owner certificate (128, 130), which is assigned to a payload database, to a first user, wherein an owner certificate is a certificate that is assigned to one or more payload databases and each user to whom it is linked has the right to enter data sets in this payload database; - providing a first interface, which allows the first user to create a second owner certificate for the payload database and to link this certificate to a second user in order to allow said second user to enter data sets in the payload database; - providing a second interface, which allows the second user, who has created a data set (106, 108) in the payload database, to create at least one access certificate (Z.Zert_U2, Z.Zert_U2, Z.Zert_U2), which specifies a type of data set access to the data set created by the second user, and to link it to the user certificate of a user who is to be granted access to this data set, wherein the linking of the at least one access certificate to the generated data set is performed such that the at least one access certificate of the user who has created the data set is stored as part of the data set in a dedicated field of the payload database, wherein the at least one access certificate contains a plurality of access certificates (Z.Zert_U2, Z.Zert_U2, Z.Zert_U2) for other certificate types; - for each of the access types, generating an index structure from the access certificates of all data sets which specifies this access type, - in response to a database query of a user accessing one or more of the indices of the access certificates created for the payload database, verifying whether the user is allocated an index access certificate (Z.Zert_U2) which allows a user knowledge of the existence of the data set in the payload database and read access to metadata of the dataset, and allowing the use of the one or more indices to carry out the database query only if the user is allocated the index access certificate; - verifying the access authorisation of the first user to a data set entered by the second user, wherein the payload database grants the access only if the first user is assigned both an owner certificate for the payload database and an access certificate for the access to the data set.