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Privacy

Private Validium is a deployment model for the Linea stack that keeps transaction data offchain while maintaining cryptographic guarantees through zero-knowledge proofs. It is designed for regulated financial institutions and applications requiring privacy, compliance controls, and selective data disclosure.

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Reach out to support.linea.build to enquire about rollup-as-a-service, wherein all or part of the operations are supported by Linea and her partners.

Validium differentiators​

In validium mode, the Linea network proves state transitions using zk-SNARKs while retaining transaction data within a private data availability layer. After blocks are produced by the sequencer, they are aggregated and batched, and a zk-SNARK proof attesting to the resulting state transition is generated and submitted to the finalization layer.

Key features​

Offchain data availability​

Transaction data is stored offchain in a private node set rather than posted to the finalization layer. Only state commitments and zero-knowledge proofs are posted onchain, ensuring transaction privacy while maintaining cryptographic guarantees.

Role-based access control​

Role-Based Access Control (RBAC) controls access to network functionality:

  • RPC endpoints: Access controlled by API keys and permissions
  • API portal: Institution-level access controls
  • Transaction visibility: Participants see only transactions they're authorized to view

Privacy and compliance​

Private Validium supports regulated financial applications:

  • Transaction privacy: Transaction details not visible on finalization layer
  • Selective disclosure: Authorized parties (auditors, regulators) can access transaction data
  • Compliance controls: Compliance checks can be enforced at the API and sequencer levels
  • Audit trails: Complete audit trails while maintaining privacy

API portal​

The API portal provides controlled access to network functionality:

  • Institution onboarding and management
  • Token issuance and management
  • Settlement workflows (CBP, PVP, DVP)
  • Balance queries and reporting

Finalization layer options​

Private Validium can finalize on:

  • Ethereum L1: direct finalization on Ethereum with higher costs and longer finality times
  • Linea Mainnet: finalization on Linea Mainnet with lower costs and faster finality

See a comparison of finalization layer options.

Use cases​

Private Validium is ideal for:

  • Regulated financial institutions: Banks, payment processors, and financial market infrastructures requiring compliance and privacy
  • Multi-party workflows: Applications where participants should not see all transaction details
  • Tokenized assets: Issuance and settlement of tokenized securities and cash
  • Cross-border payments: Settlement systems requiring privacy and compliance controls

Architecture​

Private Validium deployments include:

  • Consensus layer: Maru with Quorum-Based Byzantine Fault Tolerance (QBFT) consensus (minimum 4 nodes)
  • Execution layer: Linea Besu with sequencer plugins
  • Coordinator: Orchestrates proof generation and finalization
  • Prover: Generates zero-knowledge proofs
  • State manager: Maintains state for proof generation
  • Private RPC nodes: RBAC-protected RPC endpoints
  • API portal: Controlled access to network functionality
  • Data availability: Private node set for data storage

Security and trust​

Trust assumptions​

Private Validium requires trust in:

  • Data availability providers: Must make data available when needed
  • Validator set: Must follow consensus protocol (QBFT provides fault tolerance)
  • Finalization layer: Inherits security from Ethereum

Security features​

  • Minimum node count: 4 nodes for QBFT fault tolerance
  • Access controls: Role-Based Access control (RBAC) on RPC and API endpoints
  • Key management: Supports Web3Signer remote signing backed by a hardware security module (HSM) or key management service (KMS)
  • Network isolation: Private network topology

Data availability​

Where deployments use a private node set for data storage, participants must trust that data availability providers will make data available when needed.

Next steps​