Message Submission

eth_sendMessageBlob

Submit a message to the network.

Parameters

{
  "from": "0x...", // Sender address (20 bytes)
  "data": "0x...", // Payload (max 8192 bytes / 8 KB)
  "signature": "0x...", // ECDSA signature (65 bytes)
  "targetBlock": "0x0", // 0 = auto-assign to next available slot
  "nonce": "0x...", // Per-sender nonce scoped to the target block
  "chainId": "0x1a5", // Chain ID (421)
  "bid": "0x0", // 0 = Standard Lane, bid ≥ MinPMBid = Priority Lane
  "vdfCheckpoints": ["0x..."], // Required for Standard Lane (bid=0)
  "vdfCheckpointInterval": "0x...", // Checkpoint spacing
  "vdfIterations": "0x...", // Total iterations
  "vdfAlgVersion": "0x1" // VDF algorithm version (current: 1)
}

Response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "hash": "0x...",
    "targetBlock": "0x...",
    "actualTargetBlock": "0x...",
    "rolledOver": false
  }
}

Example: Priority Message

await provider.send("eth_sendMessageBlob", [
  {
    from: address,
    data: payload,
    signature: sig,
    targetBlock: "0x0",
    nonce: "0x" + Date.now().toString(16),
    chainId: "0x1a5",
    bid: "0x" + ethers.parseEther("0.01").toString(16),
  },
]);

Example: Free Message (SM)

// Get VDF work requirement
const work = await provider.send("eth_getMessageWork", [{ payloadSize: "0x100" }]);

// Compute VDF checkpoints (client-side)
// Submit: vdfCheckpoints[], vdfCheckpointInterval, vdfIterations, vdfAlgVersion

// Submit
await provider.send("eth_sendMessageBlob", [
  {
    from: address,
    data: payload,
    signature: sig,
    targetBlock: "0x0",
    nonce: nonceHex,
    chainId: "0x1a5",
    vdfCheckpoints,
    vdfCheckpointInterval,
    vdfIterations: work.requiredIterations,
    vdfAlgVersion: "0x1",
  },
]);

Errors

Message	Description
Invalid signature	Signature doesn't verify sender address
Payload exceeds maximum size	Message too large (exceeds maxMessageSize)
Invalid VDF proof	VDF checkpoints don't verify
Bid below minimum	Bid > 0 but < MinPMBid
Lane capacity reached	Sidecar limit reached for this slot
Sender balance insufficient	Can't cover debit auth

eth_getMessageWork

Get VDF parameters for free messages.

Parameters

{
  "payloadSize": "0x..." // Size of payload in bytes (hex)
}

Response

{
  "enabled": true,
  "baseIterations": "0x2710",
  "scalingIterationsPerKB": "0x3e8",
  "algVersion": "0x1",
  "requiredIterations": "0x2af8",
  "checkpointInterval": "0x44c",
  "expectedCheckpoints": 10
}

Field	Description
enabled	Whether VDF is required for SM (Standard Messages)
baseIterations	Base iterations (10,000)
scalingIterationsPerKB	Additional iterations per KB of payload (1,000)
algVersion	VDF algorithm version (currently 1)
requiredIterations	Total iterations for this payload size
checkpointInterval	Store checkpoint every N iterations (target: 10 checkpoints)
expectedCheckpoints	Number of checkpoints to submit