# CAC Privacy: Selective Disclosure and ZK Anchoring

#### **4.8.1 Why Privacy Is Foundational to Verifiable Governance**

In domains such as:

* Public health
* Supply chain traceability
* Disaster response logistics
* Financial aid disbursement
* Security and migration management

Clause execution often involves **sensitive data**:

* Personal identifiers
* Geolocation traces
* Forecasts with market-moving implications
* Institutional credential metadata
* Enforcement logic under sovereign control

NSF must balance:

| Goal                | Tension                                                |
| ------------------- | ------------------------------------------------------ |
| **Transparency**    | Verifiable, auditable clause execution                 |
| **Confidentiality** | Redacting sensitive data from public logs              |
| **Compliance**      | Supporting GDPR, HIPAA, and treaty-bound data handling |
| **Zero Trust**      | Ensuring trust without revealing secrets               |

The answer: **CAC Privacy Framework** powered by **Selective Disclosure** and **ZK Anchoring**.

***

#### **4.8.2 Core Privacy Constructs in CACs**

CACs support **multi-layered privacy controls**:

| Layer                      | Mechanism                                                                              |
| -------------------------- | -------------------------------------------------------------------------------------- |
| **Input-level redaction**  | Only hashes of inputs stored publicly                                                  |
| **Output filtering**       | Action-only CACs expose decisions, not reasoning                                       |
| **Selective disclosure**   | Disclose only required fields based on VC or policy scope                              |
| **ZK Anchoring**           | Zero-knowledge proofs of correct execution without revealing logic, inputs, or outputs |
| **Encrypted CAC payloads** | For DAO or jurisdiction-specific consumption                                           |
| **Sealed audit trails**    | Accessible only with proper governance credentials                                     |

***

#### **4.8.3 Selective Disclosure Model**

CAC fields are tagged:

```json
"fields": {
  "trigger": {
    "type": "sensor",
    "value": "[REDACTED]",
    "disclosure_policy": "RevealTo:WHO-VC#AdminOnly"
  },
  "outputs": {
    "action": "Revoke:ExportVC",
    "disclosure_policy": "Public"
  }
}
```

Rules are:

* Defined per clause or DAO governance
* Enforced at execution time
* Attached to the CAC and signed as metadata
* Recorded in Registry Layer and optional Access Ledger

Agents only see **what they are authorized to see**, based on:

* Role
* Jurisdiction
* Credential
* Clause trust class

***

#### **4.8.4 ZK Anchoring of Clause Execution**

For fully private clauses:

* Logic is compiled into a ZK circuit (e.g., SNARK, STARK)
* Inputs are committed via hash
* Prover generates:
  * **Proof of execution**
  * **Proof of compliance with simulation or trigger**
* Outputs are embedded or referenced separately
* Public can verify:
  * The clause ran as declared
  * Under attested input hashes
  * In governance-approved scope
  * Without seeing any raw data

Example circuit:

```json
circuit: "DisasterReliefTrigger@3.0"
proof_type: "Groth16"
verifier_contract: "eth://0x7fa8..."
commitments: {
  "input_hash": "0xabc123...",
  "clause_hash": "0xdef456..."
}
```

***

#### **4.8.5 Encrypted CAC Payloads and Decryption Policies**

CACs can contain:

* **Encrypted fields** (e.g., `sensor_data`, `personal_credentials`)
* With **recipient-specified access policies** (e.g., DAO public key, sovereign court key)
* Supporting:
  * Multi-party access
  * Timelocks
  * Jurisdictional filters
  * Emergency override logic

Encryption schemes include:

* AES-GCM (symmetric)
* ECIES (recipient-keyed)
* Proxy re-encryption (for credential-scoped redistribution)

***

#### **4.8.6 Privacy-Tiered CAC Classification**

| Tier                 | Description                                                    |
| -------------------- | -------------------------------------------------------------- |
| **Public CAC**       | All fields visible (e.g., emissions triggers, open governance) |
| **Scoped CAC**       | Inputs/outputs redacted unless in jurisdiction DAO             |
| **Confidential CAC** | Requires VC to decrypt output/action                           |
| **ZK-Proven CAC**    | No content revealed; proof only                                |
| **Ephemeral CAC**    | Action recorded; full trace sealed unless dispute raised       |

Each clause declares its `privacy_profile`:

```json
"privacy_profile": "ZK-Proven + Credential-Gated Output"
```

***

#### **4.8.7 Credential-Linked Decryption**

Only agents with matching verifiable credentials can decrypt sealed CAC components.

Example:

```json
access_control: {
  required_credential: "DisasterOpsCommanderVC",
  jurisdiction: "FRA",
  action: "Decrypt CAC payload"
}
```

This enables:

* Redacted but actionable CAC streams
* Verified internal coordination
* Minimization of data exposure
* Trustable agent autonomy

***

#### **4.8.8 Public Ledger Anchoring Without Disclosure**

CACs can be:

* **Hash-anchored to L1/L2 blockchains**
* **Time-stamped and notarized**
* **Stored as Merkle roots only**
* Without revealing:
  * Clause logic
  * Inputs
  * Agent identity
  * Simulation model

The ledger proves:

> “Something verifiable happened, and you can check inclusion if authorized.”

***

#### **4.8.9 Redaction Trails and Forensic Recovery**

Every redaction is:

* Logged
* Signed by DAO governance
* Accompanied by:
  * `RedactionReasonVC`
  * `AuditRetentionHash`
* Subject to override only by:
  * Dispute court
  * Emergency governance
  * Treaty-mandated disclosure review

This ensures **privacy does not override accountability**.

***

#### **4.8.10 Privacy in NSF as a Pillar of Trust, Not a Barrier**

In NSF:

* Transparency and privacy are not opposites—they are co-designed
* Trust is derived from **verifiable process**, not open exposure
* Auditability, not visibility, is the guarantee
* Credentials, ZKPs, and sealed CACs allow governance to scale without data leaks

Privacy is not a privilege—it is a **constitutional layer of the NSF trust protocol**.


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