I would make heavy use of old known technologies. Set up Red and Blue teams to keep everyone else honest. Enpower an inspector general to make sure corruption

I would make heavy use of old known technologies. Set up Red and Blue teams to keep everyone else honest. Enpower an inspector general to make sure corruption is kept at bay. Build highly controlled and audited sources of high quality random bits, well isolated from all other computing infrastructure. Generate one time pads at the rate of terabytes per day for physical distribution in tightly logged and controlled distributions. Centralization and tight onsite audited management of sensitive data in air-gapped environments. Data ingress only allowed in tightly controlled formats (to prevent ingress of control), via data diodes. All bulk data outgress to use one time pads. All other access through deliberately low bandwidth channels with multiple logging platforms to prevent exfiltration. Heavy use of append only filesystems. All data at rest to be cryptographically check summed and verified on a regular basis.