Cross-Chain Privacy Layer
Cross-Chain Privacy Layer - Technical Specification
This document describes how the Roru Protocol maintains privacy across multiple blockchains through a unified shielded state.
Architecture
Unified Shielded State
Concept: Single shielded state across all chains
Benefits:
Privacy maintained across chains
Unified user experience
Efficient cross-chain operations
Consistent privacy guarantees
Layer Structure
┌─────────────────────────────────────┐
│ Unified Shielded State │
│ (Privacy Layer) │
└──────────────┬──────────────────────┘
│
┌──────────┼──────────┐
│ │ │
┌───▼───┐ ┌───▼───┐ ┌───▼───┐
│Chain 1│ │Chain 2│ │Chain 3│
│Adapter│ │Adapter│ │Adapter│
└───┬───┘ └───┬───┘ └───┬───┘
│ │ │
┌───▼───┐ ┌───▼───┐ ┌───▼───┐
│Chain 1│ │Chain 2│ │Chain 3│
│Block- │ │Block- │ │Block- │
│chain │ │chain │ │chain │
└───────┘ └───────┘ └───────┘Cross-Chain Operations
Shielded Transfers
Process:
User initiates cross-chain transfer
Source chain adapter locks assets
Shielded state updated
Destination chain adapter unlocks
Privacy maintained throughout
Implementation:
fn cross_chain_transfer(
source_chain: ChainId,
dest_chain: ChainId,
amount: u64,
recipient: ShieldedAddress,
) -> Result<Transaction> {
// Lock on source chain
let lock_tx = source_adapter.lock(amount)?;
// Update shielded state
let note = create_note(amount, recipient);
shielded_state.add_note(note)?;
// Unlock on destination chain
let unlock_tx = dest_adapter.unlock(amount)?;
Ok(Transaction::CrossChain {
lock_tx,
unlock_tx,
})
}Privacy Preservation
Privacy Properties:
Source chain hidden
Destination chain hidden
Amount hidden
Recipient hidden
Complete privacy
Adapter Layer
Adapter Interface
Interface Definition:
pub trait ChainAdapter {
async fn lock_assets(&self, amount: u64) -> Result<LockTx>;
async fn unlock_assets(&self, amount: u64, proof: &Proof) -> Result<UnlockTx>;
async fn get_balance(&self, address: &Address) -> Result<u64>;
async fn submit_settlement(&self, tx: &SettlementTx) -> Result<TxHash>;
}Adapter Implementation
Ethereum Adapter:
Smart contract integration
ERC-20 token support
Gas optimization
Event listening
Solana Adapter:
Program integration
SPL token support
Transaction building
Account management
Settlement Mechanism
Unified Settlement
Settlement Process:
Transaction validated in shielded state
Settlement transactions created per chain
Transactions broadcast to chains
Confirmations received
State finalized
Settlement Code:
fn settle_cross_chain(
transaction: &Transaction,
adapters: &[ChainAdapter],
) -> Result<Vec<SettlementResult>> {
let mut results = Vec::new();
for adapter in adapters {
let settlement_tx = adapter.create_settlement(transaction)?;
let hash = adapter.submit_settlement(&settlement_tx).await?;
results.push(SettlementResult {
chain: adapter.chain_id(),
tx_hash: hash,
});
}
Ok(results)
}State Synchronization
Cross-Chain Sync
Sync Process:
Monitor all chains
Detect lock/unlock events
Update shielded state
Maintain consistency
Handle conflicts
Sync Implementation:
async fn sync_cross_chain_state(
shielded_state: &mut ShieldedState,
adapters: &[ChainAdapter],
) -> Result<()> {
for adapter in adapters {
let events = adapter.get_lock_events().await?;
for event in events {
shielded_state.process_lock(event)?;
}
let events = adapter.get_unlock_events().await?;
for event in events {
shielded_state.process_unlock(event)?;
}
}
Ok(())
}Privacy Guarantees
Cross-Chain Privacy
Privacy Properties:
No chain linkability
Unified anonymity set
No cross-chain correlation
Complete privacy
Privacy Mechanisms
Mechanisms:
Shielded state hides chains
Zero-knowledge proofs
Encrypted communications
No metadata leakage
Bridge Integration
Bridge Architecture
Bridge Components:
Lock mechanism
Proof verification
Unlock mechanism
State tracking
Bridge Flow:
Source Chain Shielded State Dest Chain
│ │ │
├─ Lock Assets ────────┼──────────────────────┤
│ │ │
│ Update State │
│ │ │
│ ├─ Unlock Assets ──────┤
│ │ │Multi-Asset Support
Asset Abstraction
Asset Handling:
Unified asset representation
Chain-specific assets
Cross-asset operations
Asset conversion
Asset Format:
pub struct CrossChainAsset {
pub chain_id: ChainId,
pub asset_id: AssetId,
pub amount: u64,
}Performance
Efficiency
Optimizations:
Batch settlements
Parallel processing
Efficient state updates
Optimized proofs
Latency
Typical Latencies:
Shielded state update: <1s
Chain settlement: Chain-dependent
Cross-chain transfer: 1-5 minutes
Final confirmation: Chain-dependent
Security
Security Properties
Security Guarantees:
Atomic operations
No double-spending
State consistency
Cryptographic security
Threat Model
Protected Against:
Cross-chain attacks
State inconsistencies
Double-spending
Privacy breaches
Conclusion
The cross-chain privacy layer provides:
Privacy: Maintained across chains
Unification: Single shielded state
Flexibility: Multiple chains
Security: Cryptographic guarantees
Efficiency: Optimized operations
Understanding this layer is essential for cross-chain development.
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