Lesson 18: XRPL EVM Sidechain - Smart Contracts Today

The XRPL EVM Sidechain is an EVM-compatible blockchain connected to XRPL:

EVM SIDECHAIN OVERVIEW

Technical Basis:
├── EVM-compatible execution environment
├── Proof of Authority consensus
├── Connected via Axelar bridge
├── XRP as gas token (bridged)
└── Full Solidity support

Relationship to XRPL:
├── Separate chain (not XRPL mainnet)
├── Assets bridge back and forth
├── Uses XRP for gas (bridged eXRP)
├── Can interact with XRPL via bridge
└── Independent validator set

┌─────────────────┐       ┌─────────────────┐
│   XRPL Mainnet  │       │  EVM Sidechain  │
│                 │       │                 │
│  - XRP native   │       │  - eXRP (gas)   │
│  - DEX, AMM     │  ←─→  │  - Smart        │
│  - Native       │ BRIDGE│    contracts    │
│    features     │       │  - Full EVM     │
│  - No custom    │       │  - PoA          │
│    contracts    │       │    consensus    │
└─────────────────┘       └─────────────────┘

PROOF OF AUTHORITY (PoA)

How It Works:
├── Approved validators run nodes
├── Validators take turns producing blocks
├── No mining/staking for consensus
├── Fast block times (~seconds)
└── Trust in validator set

Trade-offs:
├── Pro: Fast, predictable blocks
├── Pro: Low fees
├── Pro: Energy efficient
├── Con: Centralized validator set
├── Con: Trust required in validators
└── Con: Not trustless like XRPL mainnet

Validators:
├── Selected by governance
├── Known entities (not anonymous)
├── Reputation at stake
└── Different model than XRPL mainnet
```

---

BRIDGING XRP → eXRP

Step 1: LOCK
├── User sends XRP to bridge address on XRPL
├── XRP locked in multisig
└── Transaction confirmed on XRPL

Step 2: VERIFY
├── Axelar network observes lock
├── Validators confirm transaction
└── Consensus on locked amount

Step 3: MINT
├── eXRP minted on EVM Sidechain
├── Equal amount to locked XRP
├── Sent to user's EVM address
└── 1:1 ratio maintained

BRIDGING eXRP → XRP

Step 1: BURN
├── User burns eXRP on EVM Sidechain
├── Transaction confirmed
└── Amount recorded

Step 2: VERIFY
├── Axelar network observes burn
├── Validators confirm
└── Consensus reached

Step 3: UNLOCK
├── XRP unlocked on XRPL mainnet
├── Sent to user's XRPL address
└── 1:1 ratio maintained
```

BRIDGE TRUST MODEL

You Trust:
├── Axelar validator set (honest majority)
├── Bridge smart contracts (secure code)
├── Custodial multisig (no theft)
└── Cross-chain message integrity

Risks:
├── Bridge hack (smart contract exploit)
├── Validator collusion
├── Network congestion delays
├── Temporary imbalances
└── Smart contract bugs

Mitigations:
├── Axelar security track record
├── Audited contracts
├── Insurance/reserves (varies)
├── Monitoring systems
└── Rate limiting

Reality Check:
├── Bridges have been hacked in crypto
├── Axelar has good track record
├── Not risk-free
├── Consider amounts at risk
└── Production-grade but not trustless
```

BRIDGEABLE ASSETS

Native:
├── XRP ↔ eXRP (primary gas token)
└── Full 1:1 backing

Via Axelar (Cross-Chain):
├── Assets from 55+ connected networks
├── USDC, WETH, etc.
├── General Message Passing
└── Cross-chain contracts

Example Flow:
├── User has USDC on Ethereum
├── Bridge USDC to EVM Sidechain
├── Use in XRPL ecosystem DeFi
├── Bridge back when done
```

---

EVM SIDECHAIN DEVELOPMENT STACK

Languages:
├── Solidity (primary)
├── Vyper (alternative)
└── Any EVM-compatible language

Tooling:
├── Hardhat
├── Foundry
├── Remix
├── Truffle
├── OpenZeppelin
└── Standard Ethereum tools

SDKs:
├── ethers.js
├── web3.js
├── viem
└── Standard EVM libraries

Wallets:
├── MetaMask
├── Any EVM wallet
└── Configure for sidechain RPC
```

EVM SIDECHAIN NETWORK DETAILS

Mainnet:
├── Chain ID: 1440002
├── RPC: https://rpc.evm-sidechain.xrpl.org" target="_blank" rel="noopener noreferrer" class="text-cyan-400 hover:text-cyan-300 underline hover:no-underline transition-colors inline-flex items-center gap-1">https://rpc.evm-sidechain.xrpl.org">https://rpc.evm-sidechain.xrpl.org
├── Explorer: https://evm-sidechain.xrpl.org" target="_blank" rel="noopener noreferrer" class="text-cyan-400 hover:text-cyan-300 underline hover:no-underline transition-colors inline-flex items-center gap-1">https://evm-sidechain.xrpl.org">https://evm-sidechain.xrpl.org
├── Currency: eXRP
└── Documentation: xrplevm.org

Testnet (Devnet):
├── Chain ID: 1440001
├── RPC: https://rpc.devnet.xrplevm.org" target="_blank" rel="noopener noreferrer" class="text-cyan-400 hover:text-cyan-300 underline hover:no-underline transition-colors inline-flex items-center gap-1">https://rpc.devnet.xrplevm.org">https://rpc.devnet.xrplevm.org
├── Faucet: Available
└── For development

MetaMask Setup:
{
"chainName": "XRPL EVM Sidechain",
"chainId": "0x15F902", // 1440002 in hex
"rpcUrls": ["https://rpc.evm-sidechain.xrpl.org"]" target="_blank" rel="noopener noreferrer" class="text-cyan-400 hover:text-cyan-300 underline hover:no-underline transition-colors inline-flex items-center gap-1">https://rpc.evm-sidechain.xrpl.org%22%5D">https://rpc.evm-sidechain.xrpl.org"] ,
"nativeCurrency": {
"name": "eXRP",
"symbol": "eXRP",
"decimals": 18
},
"blockExplorerUrls": ["https://evm-sidechain.xrpl.org"]" target="_blank" rel="noopener noreferrer" class="text-cyan-400 hover:text-cyan-300 underline hover:no-underline transition-colors inline-flex items-center gap-1">https://evm-sidechain.xrpl.org%22%5D">https://evm-sidechain.xrpl.org"]
}
```

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

/**

• @title SimplePaymentSplitter
• @notice Splits incoming payments to multiple recipients
• @dev Demonstrates basic EVM Sidechain development
  */
  contract SimplePaymentSplitter {
  address[] public recipients;
  uint256[] public shares;
  uint256 public totalShares;

event PaymentReceived(address indexed from, uint256 amount);
event PaymentSplit(address indexed to, uint256 amount);

constructor(address[] memory _recipients, uint256[] memory _shares) {
require(_recipients.length == _shares.length, "Mismatch");
require(_recipients.length <= 10, "Too many recipients");

recipients = _recipients;
shares = _shares;

for (uint i = 0; i < _shares.length; i++) {
totalShares += _shares[i];
}
}

receive() external payable {
emit PaymentReceived(msg.sender, msg.value);
_distribute();
}

function _distribute() internal {
uint256 total = address(this).balance;

for (uint i = 0; i < recipients.length; i++) {
uint256 payment = (total * shares[i]) / totalShares;
if (payment > 0) {
(bool success, ) = recipients[i].call{value: payment}("");
require(success, "Transfer failed");
emit PaymentSplit(recipients[i], payment);
}
}
}
}
```

// deploy.js (Hardhat)
const hre = require("hardhat");

async function main() {
const recipients = [
"0x1234...", // Recipient 1
"0x5678..." // Recipient 2
];
const shares = [70, 30]; // 70/30 split

const Splitter = await hre.ethers.getContractFactory("SimplePaymentSplitter");
const splitter = await Splitter.deploy(recipients, shares);

await splitter.waitForDeployment();

console.log("PaymentSplitter deployed to:", await splitter.getAddress());
}

main().catch((error) => {
console.error(error);
process.exitCode = 1;
});
```

---

USE EVM SIDECHAIN WHEN:

✓ Need production smart contracts NOW
✓ Have existing Solidity expertise
✓ Porting existing EVM codebase
✓ Complex DeFi logic required
✓ Cross-chain interoperability needed
✓ Standard EVM tooling preferred
✓ Composability between contracts essential
✓ Flash loans, complex patterns needed

DON'T USE WHEN:

✗ Need trustless XRP on Layer 1
✗ XRPL native feature integration critical
✗ Can't accept bridge trust assumptions
✗ Transaction filtering/guarding needed
✗ Must use native XRPL accounts directly
✗ Hooks meet all requirements
```

FEATURE              EVM SIDECHAIN    HOOKS (Xahau)
──────────────────────────────────────────────────────
Status               Live mainnet     Live (Xahau)
Asset                Bridged eXRP     Native XAH
Trust model          Bridge trust     Direct on-chain
Language             Solidity         C
Tooling              Mature           Developing
Composability        Full             Limited
Flash loans          Possible         Impossible
Security model       EVM standard     Constrained
Transaction guard    No               Yes
Learning curve       EVM familiar     Hooks specific

USE CASE                    BEST PLATFORM
──────────────────────────────────────────────────────
Simple payment filter       Hooks (Xahau)
Auto-forward payments       Hooks (Xahau)
DEX aggregator              EVM Sidechain
NFT marketplace             EVM Sidechain
Lending protocol            EVM Sidechain
Account protection          Hooks (Xahau)
Cross-chain DeFi            EVM Sidechain
Simple escrow               Either
Governance/DAO              EVM Sidechain
Token vesting               EVM Sidechain

---

BRIDGING XRP TO EVM SIDECHAIN

BRIDGING BACK

BRIDGE CHARACTERISTICS

Time:
├── XRPL → EVM: ~5-15 minutes
├── EVM → XRPL: ~5-15 minutes
├── Varies with network conditions
└── Not instant (verification required)

Costs:
├── XRPL transaction fee (minimal)
├── Bridge fee (varies, ~0.1-0.5%)
├── EVM gas (paid in eXRP)
└── Total: Generally small but not zero

Minimums:
├── May have minimum bridge amounts
├── Check bridge interface
└── Typically reasonable (e.g., 10 XRP)
```

---

EVM SIDECHAIN SECURITY

Smart Contract Security:
├── Standard EVM security applies
├── Reentrancy guards needed
├── Access control important
├── Audit for production contracts
└── OpenZeppelin for standards

Bridge Security:
├── Limit amounts bridged
├── Don't bridge more than you need
├── Monitor bridge status
├── Have contingency if bridge issues
└── Understand trust assumptions

Operational Security:
├── Secure private keys
├── Use multisig for high-value
├── Monitor contract activity
├── Have upgrade plan if needed
└── Test thoroughly on devnet
```

PERFORMANCE

Block Time:
├── ~2-3 seconds
├── Fast finality
└── Predictable

Throughput:
├── Higher than XRPL mainnet
├── PoA enables speed
└── Suitable for most applications

Gas:
├── Lower than Ethereum mainnet
├── eXRP as gas token
├── Predictable costs
└── Budget appropriately
```

ONGOING OPERATIONS

Monitor:
├── Contract state
├── Bridge health
├── Gas prices
├── Validator status
└── Security alerts

Maintain:
├── Keep dependencies updated
├── Watch for new vulnerabilities
├── Plan for upgrades if needed
├── Document everything
└── Test changes on devnet first
```

---

✅ EVM Sidechain is production-ready. Live since June 2025, functional, growing ecosystem.

✅ Axelar bridge works. Assets transfer, track record established.

✅ Full EVM compatibility. Standard Solidity contracts work.

⚠️ Long-term bridge security. No major incidents, but bridges are attack targets.

⚠️ Ecosystem growth. Will developers and users adopt?

⚠️ Relationship with native XRPL. How will ecosystem evolve?

🔴 Treating bridged eXRP as identical to native XRP. Trust assumptions differ.

🔴 Bridging more than necessary. Minimize bridge exposure.

🔴 Assuming EVM security patterns are perfect. EVM has known vulnerabilities; audit carefully.

The EVM Sidechain is the only production-ready XRPL smart contract option as of late 2025. It offers full Solidity support with reasonable trust assumptions. The trade-off is using bridged assets on a Layer 2 rather than native contracts on Layer 1. For many use cases, this trade-off is acceptable. For others, waiting for Hooks on mainnet or XLS-101 may be better.

---

Assignment: Deploy and interact with a contract on EVM Sidechain testnet.

Requirements:

• Configure MetaMask for EVM Sidechain testnet

• Get testnet eXRP from faucet

• Document setup steps

• Token contract (ERC-20)

• Simple NFT (ERC-721)

• Voting contract

• Escrow contract

• Clear comments

• Events for key actions

• Basic access control

• Deploy to testnet

• Verify on explorer

• Document contract address

• Screenshot of successful deployment

• Call at least 3 contract functions

• Document transactions

• Show state changes

• Verify events emitted

• Working environment (20%)

• Contract quality (30%)

• Successful deployment (25%)

• Complete interaction documentation (25%)

Time investment: 4-6 hours
Value: Hands-on EVM Sidechain experience

---

For Next Lesson:
We'll look at the future of XRPL programmability—upcoming features, ecosystem evolution, and strategic planning.

---

End of Lesson 18

Total words: ~4,200
Estimated completion time: 55 minutes reading + 4-6 hours for deliverable