Requirements & constraints:
- Strict per-country residency (data must not leave customer’s chosen jurisdiction)
- Cross-border controls (explicit consent/whitelists for any transfer)
- DLP (PII/classification, redact or block)
- Consent management & audit trail
- Legal hold / retention overrides
- Low-latency Copilot access, secure ML training while honoring residency
High-level architecture:
- Region-aware ingestion layer → regional processing + region-bound storage → region-scoped model-serving gateways → central control plane for policy orchestration (metadata-only, no plaintext data).
Components & responsibilities:
- Regioned storage: customer documents stored in cloud storage buckets per-region (ISO region mapping). Enforce bucket-level policies, SSE with customer-managed KMS keys per region.
- Private endpoints & networking: VPC endpoints / PrivateLink so uploads and inference traffic never traverse public internet. Load balancers and model servers in same region.
- Ingest pipeline: edge agent or regional API endpoint validates consent token, performs pre-ingest DLP/classification, extracts metadata, and writes encrypted blobs to regional storage.
- DLP engine: policy-driven classifiers (regex, ML models) that can redact, tokenize, or quarantine documents. Runs synchronously on ingest and asynchronously for re-scans.
- Consent & policy store: immutable, auditable consent records (who, what, scope, TTL) stored in regional DBs. Central policy engine (OPA/Rego) evaluates requests against consent/whitelist and legal hold flags before any read/transfer.
- Legal hold & retention: metadata flags on documents preventing deletion or export; retention engine enforces holds and overrides normal TTLs; holds replicated only as metadata, not content.
- Model training & inference: training uses region-only data or privacy-preserving approaches (federated learning, secure aggregation, differential privacy, synthetic data). Global models are only updated from aggregated gradients or DP-sanitized artifacts; no raw data leaves region without explicit consent.
- Audit & monitoring: immutable audit logs (WORM) per region, real-time alerts for policy violations, periodic attestation reports.
Operational controls & automation:
- Policy-as-code: encode residency, DLP, consent rules in OPA; deploy via CI/CD to regional control planes.
- Automated enforcement hooks: pre-ingest, pre-export, runtime enforcement for model calls; deny-by-default.
- Key management: separate KMS per region, strict key usage policies, HSM-backed CMKs.
- Identity & access: least-privilege IAM roles scoped to region; service identities bound to workload and region tags; mutual TLS between services.
- Data catalog & lineage: keep metadata cataloged with provenance, consent, classification, and retention status to support legal discovery.
- Incident response: automated quarantine, forensics snapshot in-region, legal-notification workflow.
- Testing & compliance: continuous compliance tests (policy simulation, chaos tests) and yearly external audits.
Example flow (upload):
- Client hits private regional endpoint with consent token.
- Ingest service verifies token against regional consent store, runs DLP; if redaction needed, redact and store redacted + original in encrypted quarantine if policy allows.
- Write document to regional bucket, tag metadata (region, consent id, retention, holds).
- Copilot inference uses region-scoped model gateway which enforces policy engine checks before allowing prompt access to document content.
Trade-offs & rationale:
- Keeping raw data region-bound increases complexity (multi-region deployments, cost) but meets legal/regulatory constraints.
- Use privacy-preserving ML to allow global improvements without moving raw data.
- Policy-as-code + automation reduces human error and provides auditable, reproducible controls.
This design ensures data never leaves allowed jurisdictions without explicit auditable consent, enforces DLP and legal holds, and enables compliant ML workflows via federated/DP techniques and strict region scoping.
