sentences:  This is in many ways similar to DSTO's work, except that it allows a limited backchannel going from the high side to the low side for the transmission of acknowledgments.This technology allows more protocols to be used over the network, but introduces a potential covert channel if both the high- and low-side are compromised through artificially delaying the timing of the acknowledgment.Different implementations also have differing levels of third party certification and accreditation.