Privacy Preserving Verifiable Geofencing with Residency Proofs for Sovereign Workloads

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Table of Contents

1. Introduction

The Workload Identity Agent (e.g., SPIRE Agent) acts as the local-on-host intermediary responsible for managing and issuing identities to workloads. It serves as a vetting mechanism, ensuring that a workload's execution environment meets required security and residency policies before granting it the cryptographic credentials necessary for network communication. This High-Assurance Profile (a specialized RATS Profile) provides the technical mechanics to cryptographically bind this agent to the underlying hardware-verified platform and its privacy-preserving physical location.¶

The architecture follows the RATS Architecture [[RFC9334]], defining the interactions between Provers, Verifiers, and Relying Parties to generate and validate high-confidence evidence regarding the Workload Identity Agent's status. It provides the hardware-rooted evidence layer required by the WIMSE Architecture [[I-D.ietf-wimse-architecture]], establishing a "Silicon-to-Workload" chain of trust that ensures sensitive data is only processed by authorized workloads in approved, measured environments.¶

To maintain location privacy while providing cryptographic verifiability, this profile leverages Transparent Zero-Knowledge Proofs (ZKPs). Unlike traditional ZKP systems, transparent ZKPs require no trusted third party or complex trusted setup phase. They achieve mathematical transparency through non-interactive, hash-based protocols, allowing a platform to prove it is resident within an approved geographic boundary without disclosing the exact coordinates of the underlying hardware.¶

2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [[RFC2119]] [[RFC8174]] when, and only when, they appear in all capitals, as shown here.¶

3. Key Terms

Data Residency:

Requirement that data processing and storage remain within an approved geographic boundary.¶

Geofencing:

Enforcement that workloads execute only on approved hosts within an approved geographic boundary.¶

Workload Identity Agent:

On-host component that issues workload identities (for example, SVIDs) to local workloads, subject to verifier-approved evidence.¶

Location Anchor Host (LAH):

Trusted host or device that produces location evidence used to establish residency within a geofence.¶

Workload Host:

Physical or virtual machine running the Workload Identity Agent and workloads; produces platform evidence. Unless otherwise stated, this document assumes the unified deployment model in which the Workload Host and the Location Anchor Host (LAH) are the same machine.¶

Composite Geolocation:

Location estimate fused from multiple sources and accompanied by a quality indicator.¶

Proof of Residency (PoR) / Co-location:

Evidence that binds a workload (or Workload Host) to an approved local environment and geofence for a specific attestation interval.¶

Silicon Root of Trust:

Hardware trust anchor that supports measured boot and protects attestation keys.¶

Transparent Zero-Knowledge Proof:

ZKP that does not require a trusted setup; used to prove "inside an approved zone" without revealing precise coordinates.¶

Workload Identity Management Plane:

Issues and validates workload identities and trust bundles based on verifier results and policy.¶

Host Identity Management Plane:

Verifies platform integrity and residency evidence, and manages attestation key registration and platform health state (often via OOB paths).¶

V-GAP (Verifiable Geofencing Attestation Profile):

Nested evidence format defined in this document for binding identity to verified platform integrity and verified residency.¶

N_fusion (Workload Fusion Nonce):

Fresh nonce used to bind identity issuance to a specific attestation interval, delivered by the Workload Identity Management Plane. Corresponds to the nonce field in the lah-bundle.¶

4. Use Cases

This profile supports attested data residency and geofencing for workloads and (optionally) users. Common use cases fall into: server-centric enforcement, user-centric enforcement, and compliance and risk reduction.¶

5. Motivation and Gaps

Operators need to enforce where sensitive workloads run without relying on signals that are easy to spoof (IP geolocation, region labels) or credentials that are easy to steal (bearer tokens). In many systems today, platform integrity and residency are inferred from configuration and control-plane metadata rather than verified with cryptographic evidence.¶

Key gaps include:¶

• Unverifiable location metadata (data-at-rest / data-generation): Location tags for arbitrary data objects are not standardized and are typically unsigned, making provenance and integrity difficult to validate.¶
• Token theft and replay (data-in-use): Bearer tokens can be copied and replayed from unauthorized hosts or locations; stronger mechanisms exist but are not consistently deployed and can add operational overhead.¶
• Implicit trust in “region” and transit: A relying party often cannot cryptographically verify a server’s physical residency, and requests may traverse intermediaries (e.g., proxies) that expand the effective trust boundary.¶

6. What This Profile Provides

This document defines a High-Assurance Profile (a specialized RATS profile) that makes platform integrity and geofence residency verifiable inputs to authorization and credential issuance, while supporting privacy-preserving “in-zone” proofs where available.¶

At a high level, the profile enables a relying party (or identity issuer) to require evidence that: 1. the Workload Identity Agent is running on an approved, measured platform; and 2. that platform is resident within an approved geographic boundary (optionally without revealing coordinates).¶

7. Composition with Transitive Attestation and WIMSE

This profile is designed to compose with [[I-D.mw-wimse-transitive-attestation]] and the WIMSE Architecture [[I-D.ietf-wimse-architecture]].¶

• [I-D.mw-wimse-transitive-attestation]: Binds a workload to a local Workload Identity Agent (co-location / PoR), treating the agent as a trust anchor.¶

• This document (Layers 2 and 3): Defines how that Workload Identity Agent is itself verified:¶

  • Layer 2 — Platform integrity: Hardware-rooted evidence of the host state (e.g., TPM-based attestation).¶
  • Layer 3 — Residency: Cryptographically verifiable proof the attested host is inside an approved boundary (optionally privacy-preserving).¶

8. Operational Use: Gating Credentials on Verified Evidence

This profile assumes two cooperating control planes:¶

• Host Identity Management Plane: Verifies platform integrity and residency evidence and produces an attestation result.¶
• Workload Identity Management Plane: Issues or renews workload identities (e.g., SVIDs) only when the attestation result satisfies policy.¶

To prevent mix-and-match and replay, attestation results SHOULD be fresh and SHOULD be bound to the identity issuance event (e.g., by cryptographically binding freshness values used for platform quotes and workload credential issuance within the verifier result).¶

Where policy requires it, the verifier can additionally require that an agent software measurement (e.g., image digest) is covered by validated platform evidence, reducing the risk that a modified or unauthorized agent obtains credentials.¶

In intermittently connected edge deployments, local operation can continue during outages, while centralized policy can be enforced on renewal and on release of high-value secrets once connectivity is available.¶

9. High-Assurance Profile: Verifiable Geofencing Attestation Profile (V-GAP)

V-GAP is a RATS/WIMSE attestation profile that binds a Workload Identity Agent to (1) hardware-rooted host integrity and (2) verified residency within a configured geofence. It does this with an evidence bundle from a Location Anchor Host (LAH).¶

{
  "lah-bundle": { },
  "mno-endorsement": { },
  "workload": { }
}

{
  "lah-bundle": {
    "tpm-ak": "-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG...\n-----END PUBLIC KEY-----",
    "geolocation-id-hash": "7f4a2c1b9e3d8f0a6b5c4d2e1f0a9b8c...",
    "geolocation-proof-hash": "c8bc2ed62a7a650d99e0884197cdf345...",
    "privacy-technique": "zkp",
    "geolocation-payload": {
      "zkp-proof-uri": "https://verifier.example/v1/proof/c8bc2ed6...",
      "zkp-format": "plonky2"
    },
    "nonce": "ZmUyZjdmMzlmZGVlZWQxOTM1YjY0Mjk0...",
    "timestamp": 1740693456,
    "tpm-quote-seal": "ARoAAQALAAUACwEA...",
    "workload-identity-agent-image-digest": "a1b2c3d4e5f6...64-char-hex-sha256"
  },
  "mno-endorsement": {
    "mno-key-cert": "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8A...",
    "mno-sig": "MEYCIQDx9z2k..."
  },
  "workload": {
    "workload-id": "spiffe://example.org/python-app",
    "key-source": "tpm-app-key"
  }
}

chain[n] = SHA-256(chain[n-1] || SHA-256(JCS(bundle[n])))
nonce[n]  = HMAC(secret, n || chain[n-1])

{
 "new-ak-pub": "Base64URL_Encoded_Public_Key",
 "serial-number": "AK_Serial_XYZ",
 "timestamp": 1708845600,
 "hardware-uuid": "Host_Hardware_UUID",
 "signature": "Base64URL_Signature_from_Previous_AK"
}

10. Operational Considerations

11. Policy Use (Informative)

Relying parties and identity issuers can use V-GAP results as inputs to authorization.¶

• ABAC: Residency and integrity can be mandatory claims for sensitive operations.¶
• KMS gatekeeping: Release of high-value assets (for example, decryption keys) SHOULD depend on a recent successful verification result.¶
• Fail closed: If V-GAP evidence is carried in an X.509 extension and marked CRITICAL, any implementation that does not understand the extension will reject the credential.¶

12. Security Considerations

V-GAP reduces reliance on spoofable location signals and stolen tokens by making integrity and residency cryptographically verifiable. Implementers still need to address the following threats:¶

• Replay and mix-and-match: Use nonces and evidence stapling so that old location evidence cannot be combined with a fresh platform quote (or vice versa).¶
• Location spoofing: Treat sensor and network inputs as adversarial. Prefer multiple, corroborating sources where feasible, and apply conservative policy when evidence quality degrades.¶
• Relay and displacement: When proximity mechanisms are introduced in future profiles, implementers should be aware that they are vulnerable to relay attacks and anchor displacement. Mitigations (such as tight RTT-based acceptance windows and anchor health attestation) are deferred to those future profiles.¶
• Management plane compromise: OOB paths reduce dependence on the host OS but introduce dependence on the management controller and its network. Protect this plane with secure boot, authenticated updates, strong access controls, network segmentation, and audit logging.¶
• Time and freshness: Verifiers MUST enforce bounded freshness windows and MUST define recovery behavior (re-attestation, quarantine, or revocation) when clocks drift or evidence becomes stale.¶
• Registry and allowlist integrity: Protect key registries and policy stores against tampering; treat them as high-value privileged assets.¶
• Privacy: Avoid unnecessary collection or retention of precise location data. Prefer "in-zone" proofs (ZKP) where policy permits.¶

13. IANA Considerations

IANA is requested to register the following Object Identifier (OID) in the "SMI Numbers" registry under the "SMI Private Enterprise Numbers" (1.3.6.1.4.1) branch, or as appropriate for the V-GAP profile.¶

Mandatory Criticality: Implementations of this profile MUST mark the X.509 extension containing the V-GAP Evidence Bundle as CRITICAL. This ensures that non-compliant gateways fail closed rather than granting access to residency-constrained workloads.¶

• OID: 1.3.6.1.4.1.55744.1.1¶
• Description: Verifiable Geofencing Attestation Profile (V-GAP) Evidence Bundle¶
• Reference: This document.¶

14. Appendix: Open Issues

The following items are unresolved and are tracked for future revisions of this document.¶

15. Appendix: Public References for Strict Data Residency Rules

India -- Reserve Bank of India (RBI): Payment System Data Localization (2018): From RBI Circular RBI/2017-18/153 (April 6, 2018): "All system providers shall ensure that the entire data relating to payment systems operated by them are stored in a system only in India. This data should include the full end-to-end transaction details / information collected / carried / processed as part of the message / payment instruction."¶

South Korea's Data Localization Regulations -- Geospatial Information Management Act (Spatial Data Act): Article 16, Paragraph 1: Prohibits the export of state-led survey data.¶

Authors' Addresses