| 摘要 |
In a secure communication system, an adaptable security level is synchronised between devices by inserting security bits (35-37, fig. 3) into the control bits of a message frame or header (32) which indicate the selected security level (eg.0, 32, 64 or 128 bits) and whether encryption is turned on or off, thus allowing modification on a frame-by-frame basis. For multiple recipients, a minimum integrity level common to all of them can be selected. The security bits may also indicate parameters in an algorithm. Communication is organised by a network stack (Fig. 6) which passes payloads [m] and security levels (SEC) between various layers (application, network, MAC, physical etc.) and encryption keys K. Security level information may also be passed via acknowledgement (ACK) messages over a feedback channel. |
