Australia’s authority regarding signals intelligence and information security. The DSD has two primary functions: to collect and disseminate foreign signals intelligence (called Sigint) and to provide Information security (Infosec) services and products to the government and its Defence force. Though the DSD’s information security role is not classified information, the Directorate’s foreign signals intelligence role is, to a great degree, classified information. Defence Signals Directorate. Welcome to the Website of the Defence Signals Directorate. [Online, May 14, 2004.] Defence Signals Directorate Website. http://www .dsd.gov.au/.