Digital security systems are now frequently made of components networked together at distributed locations which must be monitored and controlled in a coordinated manner. Thus, these systems themselves now require a means for reliable and secure internal communications, often over a public network.

While analog systems may have components that signal each other when certain conditions are met to trigger responses elsewhere, digital systems offer the capability to recognize much more complicated sets of conditions, and activate much more detailed responses than analog systems can achieve. To do this, the components of digital security systems must exchange detailed information with each other. In scenarios demanding high levels of security, these intra-system communications may be targets of interest to intruders.

In these high-security situations, transmissions themselves must be secured. Digital systems may implement this security by encrypting their transmissions, and using authentication and authorization protocols, to protect the security system itself from attacks. These techniques can provide the secure capture, secure transmission, and secure storage that are needed to provide a secure evidence trail in the case of an undesired event.