Design of a physical layer security mechanism for CSMA/CD networks

The paper presents a hardware-oriented security scheme for the physical layer of CSMA/CD networks. In the scheme, connection and data confidentiality in CSMA/CD networks are achieved while the broadcast nature of the networks is preserved. The basic security mechanism is the encipherment of CSMA/CD frames transmitted from CSMA/CD controllers. This mechanism is implemented in a security controller inserted between a CSMA/CD controller and its transceiver. In developing the security key management mechanism in the security controller, a key number (or key reference) concept was introduced. With this new key number concept, the distribution of session keys, either by a key exchange or a key distribution centre, becomes unnecessary. The security scheme allows communications in either normal or security mode; however, stations without the security controller can only receive frames transmitted in the normal mode. Apart from the additional security controller, hardware and software alterations are not required to implement the security scheme in any existing CSMA/CD networks.<>