In one embodiment, a service receives captured traffic flow data regarding a traffic flow sent via a network between a first device assigned to a first network zone and a second device assigned to a second network zone. The service identifies, from the captured traffic flow data, one or more cryptographic parameters of the traffic flow. The service determines whether the one or more cryptographic parameters of the traffic flow satisfy an inter-zone policy associated with the first and second network zones. The service causes performance of a mitigation action in the network when the one or more cryptographic parameters of the traffic flow do not satisfy the inter-zone policy associated with the first and second network zones.