> ## Documentation Index
> Fetch the complete documentation index at: https://docs.uniblock.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# zks_getL2ToL1MsgProof

> Returns the proof for a message sent through the L1Messenger system contract, given a block, sender, message, and an optional message log index containing the L1 to L2 message.

### Parameters

<ParamField query="chainId" type="string" default="11124" required>
  Unique identifier for a blockchain network.
</ParamField>

<ParamField body="id" type="number" default={1} required>
  Request identifier used to match responses.
</ParamField>

<ParamField body="jsonrpc" type="string" default="2.0" required>
  JSON-RPC version.
</ParamField>

<ParamField body="method" type="string" default="zks_getL2ToL1MsgProof" required>
  JSON-RPC method name.
</ParamField>

<ParamField body="params" type="object" default={[5187,"0x87869cb87c4Fa78ca278dF358E890FF73B42a39E","0x22de7debaa98758afdaee89f447ff43bab5da3de6acca7528b281cc2f1be2ee9"]} placeholder="[5187,&#x22;0x87869cb87c4Fa78ca278dF358E890FF73B42a39E&#x22;,&#x22;0x22de7debaa98758afdaee89f447ff43bab5da3de6acca7528b281cc2f1be2ee9&#x22;]" required>
  Positional parameters for <code>zks\_getL2ToL1MsgProof</code>:

  <ul>
    <li><code>params\[0]</code>: The block number in which the message was emitted.</li>
    <li><code>params\[1]</code>: The address that sent the message.</li>
    <li><code>params\[2]</code>: The keccak256 hash of the message being proved.</li>
    <li><code>params\[3]</code>: Optional index in the block of the L1Messenger event log. Defaults to the first message if omitted.</li>
  </ul>
</ParamField>

### Returns

<ResponseField name="result" type="object">
  The JSON-RPC result.

  <Expandable title="properties">
    <ResponseField name="id" type="integer">
      The position of the message in the Merkle tree.
    </ResponseField>

    <ResponseField name="proof" type="array">
      The Merkle proof array for the message.

      <Expandable title="items">
        <ResponseField name="items[]" type="string" />
      </Expandable>
    </ResponseField>

    <ResponseField name="root" type="string">
      The Merkle root at the time the message was logged.
    </ResponseField>
  </Expandable>
</ResponseField>

<RequestExample>
  ```bash Curl theme={null}
  curl --request POST \
    --url https://api.uniblock.dev/uni/v1/json-rpc?chainId=11124 \
    --header 'content-type: application/json' \
    --data '{
      "id": 1,
      "jsonrpc": "2.0",
      "method": "zks_getL2ToL1MsgProof",
      "params": [
        5187,
        "0x87869cb87c4Fa78ca278dF358E890FF73B42a39E",
        "0x22de7debaa98758afdaee89f447ff43bab5da3de6acca7528b281cc2f1be2ee9"
      ]
    }'
  ```
</RequestExample>

<ResponseExample>
  ```json Success theme={null}
  {
    "jsonrpc": "2.0",
    "id": 1,
    "result": {
      "id": 0,
      "proof": [
        "0xabc123...",
        "0xdef456..."
      ],
      "root": "0xf1adac176fc939313eea4b72055db0622a10bbd9b7a83097286e84e471d2e7df"
    }
  }
  ```
</ResponseExample>