The new criteria for covert channels auditing

A new concept, the weight difference of covert channel, was represented firstly, which means the security level span that sensitive information transmits via a certain covert channel. Based on it, the new criteria for covert channels auditing was given. Not as TCSEC only use the bandwidth to evaluate the threat of covert channels, this criteria integrated the weight difference, bandwidth, working hours and instantaneous time of covert channels, so it could given a comprehensive evaluation for the threat of covert channels in multilevel security system.