For many years the Access Control and Security Industry concentrated on the security of the data exchange between the access control credential (card) and the reader.
Early systems were quickly compromised when cards were cloned and security was breached. Encrypting the data between the card and reader provided a more secure interface but there was still a weak link in the system. Having encrypted the card to reader data, this data was then passed to the access control system using industry standard Wiegand protocol. Basically, an unencrypted signal that is easily intercepted and copied.
