See Exhibit 1 for an overview of the process. Computer matching contributes greatly to the establishment and maintenance of the digital persona, because it brings together data which would otherwise be isolated. It may, in the process, jeopardise the information privacy of everyone whose data is involved, and even significantly alter the balance of power between consumers and corporations, and citizens and the State. A digital persona is of limited use unless new data can be associated with that already held. To be useful for social control, it must also be able to be related to a specific, locatable human being.
Digital identity is the means whereby data is associated with a digital persona.
Organisations which pursue relationships with individuals can generally establish an identifier for use on its master file and on transactions with or relating to the individual. The challenges are greater when multiple organisations involved. This is because the number is widely available, and its integrity regarded by the agencies as adequate. Some agencies, in order to address acknowledged quality problems, use additional data-items to confirm matches. In European countries it has been the practice for many years for a single identifier to be used for a limited range of purposes, in particular taxation, social security, health insurance and national superannuation.