Procedure, security management device and computer software product to monitor the security of a communication link between two units

摘要

The invention relates to a procedure, a security management device and a computer software product to monitor the security of a communication link between two entities, where the security of the communication link is handled by a first and a second parallel operating link security unit (20, 22);where the first link security unit (20) provides a first message (Ml) comprising data, a first numeral and a first fault detection code and the second link security unit (22) provides a second message (M2) comprising the same data, a second numeral and a second fault detection code. The security management device includes a monitoring unit (16) that accesses one of the messages, determines a third numeral and replaces the numeral in the message received with the third numeral for the modified message to be sent via the communitarian link.Figure 2