City Chain Architecture Overview
City Chain is a Layer 3 rollup designed for geographic communities, combining local governance with Ethereum's security and L{CORE}'s IoT attestation infrastructure.
System Architecture
L3 Architecture Stack
CITY-CHAIN L3 ARCHITECTURE
L3: City Chain
Local governance, IoT data, stablecoins
Nitro StackCustom PrecompilesL{CORE} Integration
L2: Arbitrum One/Nova
Batch processing, state roots
SequencerFraud Proofs
L1: Ethereum
Final settlement, security guarantees
Core Components
1. Rollup Infrastructure
The base layer that provides blockchain functionality:
| Component | Purpose | Technology |
|---|---|---|
| Sequencer | Orders transactions, produces blocks | OP Stack / Arbitrum Orbit |
| State | Maintains account balances, contract state | EVM-compatible |
| Fraud Proofs | Ensures state validity | Optimistic rollup |
| Data Availability | Stores transaction data | Arbitrum DA |
2. L{CORE} IoT Layer
The data attestation layer that brings verifiable real-world data on-chain:
IoT Device to On-Chain Architecture
Edge Layer
IoT Devices
- ESP32/Arduino
- Raspberry Pi
- Sensors
Attestation
Reclaim TEE
- Verify signatures
- zkTLS proofs
- did:key auth
On-Chain
City Chain L3
- SQLite storage
- Privacy buckets
- Query API
Key capabilities:
- Device Identity — Every IoT device has a did:key for cryptographic signatures
- TEE Verification — Reclaim Protocol's attestor verifies device signatures in a trusted environment
- Privacy Buckets — Sensitive data stored as ranges ("temperature: 20-25°C")
- Fraud Proofs — Cartesi rollup provides verifiable data storage
See L{CORE} Documentation for details.
3. Application Layer
Smart contracts and dApps built on City Chain:
- Local Payments — Low-cost, instant transactions in local currency
- Locale Lending — Community lending pools connecting local investors and borrowers
- Governance — On-chain voting for community decisions
- Data Marketplace — Residents sell verified sensor data
4. Governance Layer
Community-controlled protocol management:
- Voting — Token-weighted or quadratic voting on proposals
- Treasury — Community-managed funds from transaction fees
- Upgrades — Coordinated protocol improvements
- Parameters — Gas limits, fee structures, access controls
Data Flow
Transaction Flow
City Chain Transaction Flow
User
L3
L2
L1
Submit
TransactionExecute
~250msBatch
~10minFinality
~15minIoT Data Flow
City Chain IoT Data Flow
Sensor
Read data
SDK
Sign + bucket
Attestor
Verify TEE
L3 Storage
Encrypted
Security Model
Inherited Security (Ethereum → Arbitrum → City Chain)
| Layer | Security Guarantee |
|---|---|
| Ethereum L1 | Proof-of-stake consensus, $40B+ staked |
| Arbitrum L2 | Fraud proofs, 7-day challenge period |
| City Chain L3 | Inherits Arbitrum security via settlement |
IoT Data Security (L{CORE})
| Component | Security Guarantee |
|---|---|
| Device Signatures | did:key cryptographic identity |
| TEE Attestor | Hardware-secured verification (Reclaim Protocol) |
| Cartesi Rollup | Deterministic execution with fraud proofs |
| Privacy | NaCl encryption, privacy buckets |
Integration Points
For dApp Developers
| Integration | Description |
|---|---|
| RPC Endpoint | Connect via standard EVM JSON-RPC |
| Contract Deployment | Deploy Solidity contracts like any EVM chain |
| L{CORE} Queries | Query IoT attestations via L{CORE} SDK |
See Building on Locale for complete integration guides.
For IoT Device Operators
| Step | Description |
|---|---|
| Generate Identity | Create device did:key via L{CORE} SDK |
| Configure Attestor | Connect to L{CORE} attestor endpoint |
| Submit Data | Send signed sensor readings |
See L{CORE} Device Setup for complete device integration guides.
Next Steps
- Layer 3 Design — Deep dive into L3 architecture
- Rollup Infrastructure — Sequencer and state management
- L{CORE} Integration — Connecting IoT devices
- Governance Model — Community decision-making