The ACTS programme, Advanced Communications Technologies and Services, has boosted research and development in the area of security and safety of communications systems and services. Within this programme a research cooperation was launched in order to investigate security requirements between Integrated Services Digital Networks (ISDN) and Asynchronous Transfer Mode (ATM). This research project, SCAN, security communication in ATM networks, resulted in a single chip ATM encryptor that is applicable to a wide range of ATM end systems. This single chip encryptor goes by the name of HADES that stands for High-speed ATM Des/TripleDes. It is a very large scaled integrated circuit (VLSI) that supports Data Encryption Standard (DES) and two-key TripleDES in cipher block chaining (CBC) and electronic codebook (ECB) operational mode. The transfer coverage can go up to 155 Mbits per second even though such high rates are not required in ISDN. The cell-payload encryption is conformant to the ATM Forum Security Specification 1.0 which is the framework for secure communication in ATM network environments. In order to achieve efficient encryption-context switching there is a content addressable memory (CAM) on the chip, as well as RAM. Since unavoidably an on-chip memory is limited in size there is an interface to commercial ATM CAM and RAM components.This way there is no limit in the number of virtual connections (VC's) that can be supported. HADES with many more technical features is able to provide a comprehensive solution to ISDN security.Broadband network technologies have changed the way we live and will do so even more in the near future. We will communicate and work more and more through multimedia applications and this calls for the greatest possible security and confidentiality. HADES, a novel single-chip approach to encryption, has been developed to safeguard the gates of our communications much like the ancient god safeguarded the gates of the underworld.