> For the complete documentation index, see [llms.txt](/llms.txt).

# `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[​](#parameters "Direct link to Parameters")

- `block`: (integer) [_Required_] Block where the message was emitted.
- `sender`: (string) [_Required_] The sender (account) of the message.
- `msg`: [_Required_] The keccak256 hash of the sent message.
- `l2_log_position`: The index in the block of the event that was emitted by the L1Messenger when submitting this message. If it is omitted, the proof for the first message is returned.

## Response[​](#response "Direct link to Response")

- `id` - The position of the leaf in the Merkle tree of L2 to L1 messages for the block.
- `proof` - The Merkle proof for the message.
- `root` - The root hash representing the Merkle tree root at the time the log was generated.

## Example[​](#example "Direct link to Example")

Replace `<YOUR-API-KEY>` with an API key from your [Infura dashboard](https://app.infura.io/).

### Request[​](#request "Direct link to Request")

- curl
- WSS

```
curl https://zksync-mainnet.infura.io/v3/<YOUR-API-KEY> \
  -X POST \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc": "2.0", "id": 1, "method": "zks_getL2ToL1MsgProof", "params": [5187, "0x87869cb87c4Fa78ca278dF358E890FF73B42a39E", "0x22de7debaa98758afdaee89f447ff43bab5da3de6acca7528b281cc2f1be2ee9"]}'

```

```
wscat -c wss://zksync-mainnet.infura.io/ws/v3/<YOUR-API-KEY> -x '{"jsonrpc": "2.0", "id": 1, "method": "zks_getL2ToL1MsgProof", "params": [5187, "0x87869cb87c4Fa78ca278dF358E890FF73B42a39E", "0x22de7debaa98758afdaee89f447ff43bab5da3de6acca7528b281cc2f1be2ee9"]}'

```

### Response[​](#response-1 "Direct link to Response")

- JSON

```
{
  "jsonrpc": "2.0",
  "result": "0x25f64db",
  "id": 2
}

```