LP-535: Verifiable Data Integrity Seal Protocol

Abstract

LP-0535 specifies the Verifiable Data Integrity Seal Protocol (VDIS), a unified framework for creating tamper-proof, independently verifiable cryptographic seals over arbitrary data using the Lux FHE+ZK stack. A DataSeal binds a cryptographic fingerprint of any digital asset -- documents, AI models, media files, financial records, sensor readings -- to the Z-Chain Receipt Registry (LP-0530) via Poseidon2 hashing (LP-3658) and STARK/SNARK verification (LP-0510). Seals are independently verifiable without reliance on any central authority, exportable cross-chain via Groth16 wrappers, and optionally privacy-preserving through FHE encryption (LP-200) or ZK selective disclosure. The protocol provides a scalable, blockchain-anchored alternative to centralized verification services, enabling court-admissible proof of data authenticity, AI model provenance, media integrity, and regulatory compliance at enterprise scale.

Motivation

The Trust Crisis

Digital data integrity faces unprecedented challenges:

AI-Generated Content: Deepfakes, synthetic media, and LLM-generated text are indistinguishable from authentic content, eroding trust in journalism, legal evidence, and business records.
Data Manipulation: Cybercriminals alter financial records, audit logs, and compliance documents at scale. By 2030, fraud costs are projected to exceed $10 trillion annually.
Model Tampering: AI/ML models can be poisoned, backdoored, or altered post-training without detection, creating liability for enterprises deploying AI systems.
Regulatory Pressure: The EU AI Act, US Executive Order on AI Safety, and emerging global frameworks demand auditable, verifiable AI governance and data provenance.

Why Existing Solutions Fail

Approach	Limitation
Manual review	Does not scale; subjective
Centralized signatories	Single point of failure; trust bottleneck
Private hashing	No independent verification; non-repudiation gap
Timestamping services	Centralized; no proof of content integrity
Traditional blockchain	Expensive at scale; no privacy; no ZK proofs

The Lux Advantage

The Lux FHE+ZK stack provides a unique combination of capabilities:

ZK Proof Verification (LP-0510): Verify computational integrity without revealing inputs
Receipt Registry (LP-0530): Canonical on-chain proof storage with Merkle accumulator
Poseidon2 Hashing (LP-3658): ZK-friendly, post-quantum-safe cryptographic fingerprints at 2M hashes/sec
FHE Encryption (LP-200): Compute over encrypted data without decryption
fheCRDT (LP-6500): Privacy-preserving document management with DA integration
Cross-Chain Export (LP-0530): Groth16 wrapper proofs for external verification

VDIS unifies these primitives into a single, product-level protocol.

Specification

Core Concepts

DataSeal

A DataSeal is an immutable cryptographic binding between:

A data fingerprint (Poseidon2 hash of the sealed content)
A seal metadata envelope (creator, timestamp, schema, classifications)
A Z-Chain receipt (on-chain proof of existence and integrity)
An optional Merkle inclusion proof (for independent offline verification)

struct DataSeal {
    bytes32 sealId;              // Unique seal identifier
    bytes32 contentHash;         // Poseidon2(content)
    bytes32 metadataHash;        // Poseidon2(metadata)
    uint32  sealType;            // Type of sealed content
    uint64  timestamp;           // Block timestamp at seal creation
    address creator;             // Seal creator address
    bytes32 receiptId;           // LP-0530 receipt reference
    uint32  proofSystemId;       // Proof system used (1=STARK, 2=Groth16, etc.)
    bytes32 merkleRoot;          // Root at time of sealing
    bytes   inclusionProof;      // Merkle path for offline verification
}

Seal Types

Type ID	Name	Description	Use Case
1	`DOCUMENT`	Text documents, PDFs, legal filings	Legal, compliance
2	`MEDIA`	Images, audio, video files	Journalism, content auth
3	`AI_MODEL`	ML model weights, architectures	AI governance
4	`AI_OUTPUT`	LLM/model inference outputs	AI content provenance
5	`DATASET`	Training data, datasets	Data provenance
6	`TRANSACTION`	Financial records, trades	Finance, audit
7	`IOT_READING`	Sensor data, telemetry	Supply chain, IoT
8	`SOFTWARE`	Code, binaries, configurations	Software supply chain
9	`IDENTITY`	Credentials, attestations	KYC, identity
10	`EVIDENCE`	Court evidence, whistleblower data	Legal proceedings
11-99	Reserved	Future standard types	-
100+	Custom	Application-defined types	-

Seal Metadata

struct SealMetadata {
    string  contentType;         // MIME type (e.g., "application/pdf")
    string  schema;              // Metadata schema version
    bytes32 previousSealId;      // Chain of seals (for versioned documents)
    bytes32 parentSealId;        // Hierarchical sealing (model → output)
    string  description;         // Human-readable description
    bytes   extensions;          // Application-specific metadata (ABI-encoded)
}

Precompile Interface

Address Map

Address	Name	Description
`0x0535`	`SEAL_REGISTRY`	Main seal creation and query interface
`0x0536`	`SEAL_VERIFY`	Seal verification and validation
`0x0537`	`SEAL_BATCH`	Batch sealing for high-volume scenarios
`0x0538`	`SEAL_PRIVACY`	Privacy-preserving seal operations

Seal Creation

interface IDataSealRegistry {
    /// @notice Create a seal for data content
    /// @param contentHash Poseidon2 hash of the content being sealed
    /// @param sealType Type classification (see Seal Types)
    /// @param metadata Encoded SealMetadata
    /// @return sealId Unique seal identifier
    /// @return receiptId LP-0530 receipt reference
    function createSeal(
        bytes32 contentHash,
        uint32 sealType,
        bytes calldata metadata
    ) external returns (bytes32 sealId, bytes32 receiptId);

    /// @notice Create a seal with ZK proof of content properties
    /// @param contentHash Poseidon2 hash of the content
    /// @param sealType Type classification
    /// @param metadata Encoded SealMetadata
    /// @param proof ZK proof of content properties (e.g., "content is unaltered")
    /// @param publicInputs Public inputs to the proof
    /// @return sealId Unique seal identifier
    function createVerifiedSeal(
        bytes32 contentHash,
        uint32 sealType,
        bytes calldata metadata,
        bytes calldata proof,
        bytes32[] calldata publicInputs
    ) external returns (bytes32 sealId);

    /// @notice Create a privacy-preserving seal (content hash encrypted)
    /// @param encryptedContentHash FHE-encrypted content hash
    /// @param sealType Type classification
    /// @param metadata Encoded SealMetadata (may be partially encrypted)
    /// @return sealId Unique seal identifier
    function createPrivateSeal(
        bytes calldata encryptedContentHash,
        uint32 sealType,
        bytes calldata metadata
    ) external returns (bytes32 sealId);
}

Seal Verification

interface IDataSealVerify {
    /// @notice Verify a seal against content
    /// @param sealId The seal to verify
    /// @param contentHash Poseidon2 hash of the content to check
    /// @return valid True if content matches the sealed hash
    /// @return seal The full DataSeal record
    function verifySeal(
        bytes32 sealId,
        bytes32 contentHash
    ) external view returns (bool valid, DataSeal memory seal);

    /// @notice Verify a seal using only the inclusion proof (offline-capable)
    /// @param seal The DataSeal with inclusion proof
    /// @param merkleRoot The trusted Merkle root
    /// @return valid True if the seal is authentic
    function verifyOffline(
        DataSeal calldata seal,
        bytes32 merkleRoot
    ) external pure returns (bool valid);

    /// @notice Verify a chain of seals (document version history)
    /// @param sealIds Ordered list of seal IDs in the chain
    /// @return valid True if the chain is unbroken and authentic
    /// @return chainLength Number of valid seals in chain
    function verifySealChain(
        bytes32[] calldata sealIds
    ) external view returns (bool valid, uint256 chainLength);

    /// @notice Verify a parent-child seal relationship (model → output)
    /// @param parentSealId The parent seal (e.g., AI model)
    /// @param childSealId The child seal (e.g., model output)
    /// @return valid True if the relationship is authentic
    function verifyLineage(
        bytes32 parentSealId,
        bytes32 childSealId
    ) external view returns (bool valid);
}

Batch Sealing

interface IDataSealBatch {
    /// @notice Seal multiple items in a single transaction
    /// @param contentHashes Array of Poseidon2 content hashes
    /// @param sealTypes Array of seal type classifications
    /// @param metadataArray Array of encoded metadata
    /// @return sealIds Array of created seal identifiers
    function batchSeal(
        bytes32[] calldata contentHashes,
        uint32[] calldata sealTypes,
        bytes[] calldata metadataArray
    ) external returns (bytes32[] memory sealIds);

    /// @notice Create a Merkle tree seal over a batch of items
    /// @param contentHashes Array of content hashes (tree leaves)
    /// @param sealType Common seal type for all items
    /// @param batchMetadata Metadata for the batch as a whole
    /// @return batchSealId Seal for the batch root
    /// @return itemSealIds Individual seals for each item
    function batchTreeSeal(
        bytes32[] calldata contentHashes,
        uint32 sealType,
        bytes calldata batchMetadata
    ) external returns (bytes32 batchSealId, bytes32[] memory itemSealIds);
}

Privacy Operations

interface IDataSealPrivacy {
    /// @notice Prove a sealed document has a property without revealing content
    /// @param sealId The seal to prove against
    /// @param propertyProof ZK proof of the property
    /// @param propertyId Identifier for the property being proven
    /// @return valid True if the property holds
    function proveProperty(
        bytes32 sealId,
        bytes calldata propertyProof,
        bytes32 propertyId
    ) external view returns (bool valid);

    /// @notice Reveal a seal's content hash to a specific party (FHE re-encryption)
    /// @param sealId The private seal
    /// @param recipientPubKey Recipient's public key for re-encryption
    /// @return reEncryptedHash Content hash re-encrypted for recipient
    function selectiveDisclose(
        bytes32 sealId,
        bytes calldata recipientPubKey
    ) external returns (bytes memory reEncryptedHash);

    /// @notice Prove two private seals reference the same content (without revealing it)
    /// @param sealId1 First seal
    /// @param sealId2 Second seal
    /// @param equalityProof ZK proof of equality
    /// @return equal True if seals reference identical content
    function proveEquality(
        bytes32 sealId1,
        bytes32 sealId2,
        bytes calldata equalityProof
    ) external view returns (bool equal);
}

Gas Schedule

Operation	Gas Cost	Notes
`createSeal`	50,000	Includes Poseidon2 hash + receipt creation
`createVerifiedSeal`	50,000 + proof_gas	Additional cost for ZK proof verification
`createPrivateSeal`	75,000	FHE encryption overhead
`verifySeal`	5,000	Read-only verification
`verifyOffline`	3,000	Pure computation, no storage reads
`verifySealChain`	5,000 × N	N = chain length
`verifyLineage`	10,000	Two seal reads + relationship check
`batchSeal`	30,000 + 20,000 × N	Amortized batch overhead
`batchTreeSeal`	50,000 + 15,000 × N	Merkle tree construction
`proveProperty`	10,000 + proof_gas	ZK proof verification
`selectiveDisclose`	100,000	FHE re-encryption
`proveEquality`	20,000 + proof_gas	ZK equality proof

Seal Lifecycle

                    ┌──────────┐
                    │  Content  │
                    │  (file,   │
                    │  model,   │
                    │  media)   │
                    └─────┬────┘
                          │
                    ┌─────▼────┐
                    │ Poseidon2 │
                    │   Hash    │ ← LP-3658
                    └─────┬────┘
                          │
              ┌───────────┼───────────┐
              │           │           │
        ┌─────▼────┐ ┌───▼───┐ ┌────▼─────┐
        │  Public   │ │  ZK   │ │ Private  │
        │   Seal    │ │ Seal  │ │  Seal    │
        │           │ │       │ │ (FHE)    │
        └─────┬────┘ └───┬───┘ └────┬─────┘
              │           │          │
              └───────────┼──────────┘
                          │
                    ┌─────▼────┐
                    │ Receipt  │
                    │ Registry │ ← LP-0530
                    └─────┬────┘
                          │
                    ┌─────▼────┐
                    │  Merkle  │
                    │   Root   │ ← Poseidon2 tree
                    └─────┬────┘
                          │
              ┌───────────┼───────────┐
              │           │           │
        ┌─────▼────┐ ┌───▼────┐ ┌───▼──────┐
        │ On-Chain  │ │ Cross- │ │ Offline  │
        │  Query    │ │ Chain  │ │ Verify   │
        │           │ │ Export │ │ (proof)  │
        └──────────┘ └────────┘ └──────────┘

Cross-Chain Export

Seals can be verified on external chains via two mechanisms:

Groth16 Wrapper (LP-0530 export): Wrap the Merkle inclusion proof in a Groth16 proof verifiable on Ethereum or any EVM chain
Light Client Proof (LP-6350): Use Lux light client to verify the Z-Chain block containing the seal

/// Export a seal for cross-chain verification
function exportSeal(bytes32 sealId) external returns (
    bytes memory groth16Proof,    // Verifiable on external EVM chains
    bytes32 merkleRoot,           // Z-Chain Merkle root
    uint256 blockNumber,          // Block containing the root
    bytes memory blockProof       // Light client block proof
);

REST API

For non-blockchain integrations, the Z-Chain exposes a REST API:

Endpoint	Method	Description
`/seal/create`	POST	Create a new data seal
`/seal/{sealId}`	GET	Retrieve seal details
`/seal/{sealId}/verify`	POST	Verify content against a seal
`/seal/{sealId}/proof`	GET	Get Merkle inclusion proof
`/seal/{sealId}/export`	GET	Export for cross-chain verification
`/seal/batch`	POST	Batch seal creation
`/seal/chain/{sealId}`	GET	Get seal chain (version history)
`/seal/lineage/{sealId}`	GET	Get parent/child seal relationships

RPC Methods

Method	Description
`seal_create`	Create a data seal
`seal_verify`	Verify seal against content hash
`seal_get`	Query seal by ID
`seal_getProof`	Get Merkle inclusion proof
`seal_export`	Export seal with Groth16 wrapper
`seal_batch`	Batch seal creation
`seal_verifyChain`	Verify seal version chain
`seal_verifyLineage`	Verify parent-child relationship
`seal_proveProperty`	ZK property proof on sealed content

Rationale

Why Poseidon2 for Content Hashing

Hash Function	PQ-Safe	ZK-Friendly	Speed	Choice
SHA-256	Yes	No (expensive in circuits)	Fast	-
Keccak-256	Yes	No (expensive in circuits)	Fast	-
Poseidon2	Yes	Yes (native in STARK/SNARK)	2M/sec	Selected
Pedersen	No	Yes	1K/sec	Legacy only

Poseidon2 enables efficient ZK proofs about sealed content (e.g., "this document contains field X with value Y" without revealing the full document) because the hash can be verified inside a ZK circuit at ~300 constraints vs. ~25,000 for SHA-256.

Why Three Seal Modes

Public Seal: Maximum transparency. Anyone can verify. Suitable for journalism, open-source software, public records.
ZK Seal: Content hidden, properties provable. Suitable for trade secrets, proprietary models, confidential transactions.
Private Seal: Content encrypted via FHE. Selective disclosure to authorized parties. Suitable for whistleblower evidence, medical records, classified information.

Seal Chains vs. Seal Trees

Seal Chains (linear version history):

SealV1 → SealV2 → SealV3  (document revisions)

Seal Trees (hierarchical provenance):

ModelSeal ──→ OutputSeal1
           ├─→ OutputSeal2
           └─→ OutputSeal3

Both are supported because real-world data relationships are both sequential (document versions) and hierarchical (model → outputs).

Use Cases

1. AI Model Provenance

1. Train model → hash weights → createSeal(hash, AI_MODEL, metadata)
2. Run inference → hash output → createVerifiedSeal(hash, AI_OUTPUT, metadata, proof)
   where proof demonstrates output was produced by sealed model
3. verifyLineage(modelSealId, outputSealId) → confirms provenance chain

2. Investigative Journalism

1. Journalist obtains source document
2. createSeal(hash, DOCUMENT, metadata) → immutable timestamp
3. Edits published with verifySealChain() showing version history
4. Court subpoena → exportSeal() provides cross-chain verifiable proof

3. Whistleblower Protection

1. Whistleblower seals evidence: createPrivateSeal(encHash, EVIDENCE, metadata)
2. Existence proven without revealing content (seal is on-chain, content is encrypted)
3. Selective disclosure: selectiveDisclose(sealId, investigatorPubKey)
4. Investigator verifies: verifySeal(sealId, contentHash)

4. AI Regulatory Compliance (EU AI Act)

1. Seal training dataset: batchSeal(datasetHashes, DATASET, metadata)
2. Seal model: createSeal(modelHash, AI_MODEL, metadata)
3. Seal inference outputs: createVerifiedSeal(outputHash, AI_OUTPUT, ...)
4. Regulator audits: verifySealChain() + verifyLineage() → full provenance

5. Enterprise Document Integrity

1. Financial report created → createSeal(hash, DOCUMENT, metadata)
2. Quarterly review → verifySeal(sealId, hash) confirms no tampering
3. Cross-org verification → exportSeal() for partner chain verification
4. Audit trail → seal chain shows complete document history

6. Media Content Authentication

1. Photographer captures image → createSeal(hash, MEDIA, metadata)
   metadata includes: camera EXIF, GPS, timestamp
2. Published online → verifySeal() confirms original
3. Deepfake detected → compare against sealed original
4. Legal proceeding → exportSeal() for court-admissible proof

7. Cyber Insurance Claims

1. System logs sealed in real-time: batchSeal(logHashes, DOCUMENT, ...)
2. Incident occurs → sealed logs prove pre-incident state
3. Claim filed → verifySealChain() proves log integrity
4. Insurer verifies → exportSeal() for independent verification

Backwards Compatibility

This LP introduces new precompile addresses (0x0535-0x0538) that do not conflict with existing allocations. The protocol builds on and is fully compatible with:

LP-0530 Receipt Registry (receipts are stored there)
LP-0510 STARK Verification (proofs use existing verification)
LP-3658 Poseidon2 (hashing uses existing precompile)
LP-200 fhEVM (privacy seals use existing FHE operations)

No changes to existing LP interfaces are required.

Test Cases

Unit Tests

Test	Description	Expected
`TestCreateSeal`	Create seal with valid content hash	Seal ID returned, receipt created
`TestVerifySeal`	Verify seal against correct content	`valid = true`
`TestVerifySealWrongContent`	Verify seal against wrong content	`valid = false`
`TestCreateVerifiedSeal`	Create seal with ZK proof	Seal created, proof verified
`TestCreatePrivateSeal`	Create FHE-encrypted seal	Seal created, hash encrypted
`TestVerifySealChain`	Verify document version chain	All links valid
`TestVerifyLineage`	Verify model→output relationship	Lineage confirmed
`TestBatchSeal`	Seal 100 items in one transaction	All seals created
`TestBatchTreeSeal`	Create Merkle tree over batch	Root seal + item seals
`TestExportSeal`	Export seal with Groth16 wrapper	Valid cross-chain proof
`TestOfflineVerify`	Verify seal without chain access	`valid = true` with proof
`TestSelectiveDisclose`	Re-encrypt hash for recipient	Recipient can decrypt
`TestProveProperty`	ZK proof of content property	Property verified
`TestProveEquality`	Prove two private seals match	Equality confirmed
`TestGasAccuracy`	Verify gas costs match schedule	Within 5% of spec

Integration Tests

Test	Description
`TestSealToReceiptRegistry`	Verify seals appear in LP-0530 registry
`TestSealCrossChainExport`	Export seal, verify on mock external chain
`TestSealWithFheCRDT`	Seal fheCRDT document updates
`TestSealAIModelPipeline`	Full model→output provenance chain
`TestBatchScaling`	Seal 10,000 items, verify gas scaling

Performance Benchmarks (Target)

Operation	Target Latency	Target Throughput
`createSeal`	< 10ms	10,000 seals/sec
`verifySeal`	< 1ms	100,000 verifications/sec
`batchSeal(100)`	< 50ms	200,000 items/sec (batched)
`exportSeal`	< 100ms	1,000 exports/sec

Reference Implementation

Implementation location: geth/precompile/contracts/dataseal/

dataseal/
├── seal_registry.go          // Core seal creation and storage
├── seal_verify.go            // Verification logic
├── seal_batch.go             // Batch operations
├── seal_privacy.go           // FHE and ZK privacy operations
├── seal_export.go            // Cross-chain export with Groth16
├── seal_types.go             // Type definitions and constants
├── seal_registry_test.go     // Unit tests
├── seal_integration_test.go  // Integration tests
└── seal_bench_test.go        // Performance benchmarks

Security Considerations

Content Hash Collision Resistance

Poseidon2 provides 128-bit security against collision attacks. For applications requiring higher security, double-hashing (Poseidon2 + SHA-256) is supported via the metadata extensions field.

Seal Immutability

Once a seal is created and its receipt is included in the Merkle tree, it cannot be modified or deleted. This is enforced by the LP-0530 Receipt Registry's append-only design.

Privacy Seal Key Management

Private seals depend on FHE key management (LP-203, K-Chain). Key compromise would allow decryption of private seal content hashes. Mitigations:

Threshold FHE (LP-6474) distributes key custody
Key rotation creates new seals for ongoing data
Forward secrecy ensures past seals remain protected after rotation

Denial of Service

Batch sealing could be used to spam the registry. Mitigations:

Gas costs scale linearly with batch size
Rate limiting at the RPC layer
Minimum stake requirement for high-volume sealers

Cross-Chain Verification Trust

Exported seals are only as trustworthy as the Groth16 proof and the light client verification. Users should verify:

The Groth16 verification key matches the known Z-Chain circuit
The Merkle root is included in a finalized Z-Chain block
The light client proof is valid against the known validator set

Quantum Resistance

All cryptographic operations in VDIS are post-quantum safe:

Poseidon2: Algebraic hash, no discrete log dependency
STARK proofs: Hash-based, quantum-resistant
FHE: Lattice-based, quantum-resistant

Groth16 export proofs (pairing-based) are NOT post-quantum safe. A STARK-based export pathway is planned for LP-0510 v2.

Economic Impact

Fee Structure

Seal creation fees are set to be economically accessible while preventing spam:

Single seal: ~$0.01 at typical gas prices
Batch seal (100 items): ~$0.50 (5x amortization)
Enterprise tiers possible via staking-based fee discounts

Market Opportunity

The global data integrity verification market is projected at $8.4B by 2028. VDIS positions Lux Network as infrastructure for:

AI governance and compliance
Digital media authentication
Enterprise document integrity
Cyber insurance automation
Supply chain verification

Verifiable Data Integrity Seal Protocol