The project Secure Communiction in ATM Networks (SCAN) funded by the European Commission DG XIII under the Advanced Communications Technologies & Services (ACTS) Programme is targeting ATM cell level based user plane security. Therefore, an ATM network interface card (ATM NIC) equipped with high-speed DES/TripleDES encryption hardware is developed. In addition, the control plane and user plane security services needed for key negotiation and encryption state maintenance are integral part of SCAN. Consequently, a comprehensive solution to security in ATM networks is aimed to, compliant to the Security Specification Version 1.0. Both ATM LANs, and public ATM networks are targeted by providing two physical interfaces, the 155 Mbit/s OC3c, and the 2 Mbit/s G.703.