Step 4: Sign & Submit

Transaction Signing Process

CRITICAL: Sign transaction parameters without modification. Any alteration will result in execution failure.


const signedTx = await signer.signTransaction(
  data.mevProtection.transactionParams
);
 
// Output: RLP-encoded signed transaction (hex string)
// Format: "0x02f8b30182..." (EIP-1559 transaction)

Order Submission via MEV-Protected Routing


const submitResponse = await fetch("https://api.unikron.ch/api/v1/mev/orders", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.UNIKRON_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    signedTransaction: signedTx,
  }),
});
 
const { ok, data: order } = await submitResponse.json();
if (ok) {
  console.log(`ORDER_SUBMITTED: ${order.orderId}`);
  console.log(`TRANSACTION_HASH: ${order.txHash}`);
} else {
  console.error(`SUBMISSION_FAILED: ${submitResponse.error}`);
}

Transaction Routing Flow


Client → UNIKRON API → MEV Blocker RPC → Block Builders → Ethereum Validators
         [Validation]   [Private Mempool]  [Auction]      [Inclusion]
                        [MEV Protection]

Security Benefits

MEV Protection Advantages:

Frontrunning Protection: Transaction not visible in public mempool
Sandwich Attack Prevention: Private routing eliminates attack surface
Builder Auction: Competitive block building ensures fair execution
Best Execution Standard: Transaction routing optimized for price and execution quality

Previous: Step 3: Token Approval Next: Step 5: Transaction Monitoring