In the case of a supply chain attack, you don't even need ingress or egress. Say the posgres binary or image is set to encrypt the data on a certain date. Then

In the case of a supply chain attack, you don't even need ingress or egress. Say the posgres binary or image is set to encrypt the data on a certain date. Then it asks you to pay X ZEC to a shielded address to get your decryption key. This would work even if the actual database was airgapped.