# eth\_getStorageAt

Returns the value from a storage position at a given address.

**Parameters**

1. `DATA`, 20 Bytes - address of the storage.
2. `QUANTITY` - integer of the position in the storage.
3. `QUANTITY|TAG` - integer block number, or the string `"latest"`, `"earliest"` or `"pending"`, see the default block parameter

**Returns**

`DATA` - the value at this storage position.

**Example** Calculating the correct position depends on the storage to retrieve. Consider the following contract deployed at `0x295a70b2de5e3953354a6a8344e616ed314d7251` by address `0x391694e7e0b0cce554cb130d723a9d27458f9298`.

```
contract Storage {
    uint pos0;
    mapping(address => uint) pos1;
    function Storage() {
        pos0 = 1234;
        pos1[msg.sender] = 5678;
    }
}
```

Retrieving the value of pos0 is straight forward:

```js
curl -X POST --data '{"jsonrpc":"2.0", "method": "eth_getStorageAt", "params": ["0x295a70b2de5e3953354a6a8344e616ed314d7251", "0x0", "latest"], "id": 1}' localhost:8545
{"jsonrpc":"2.0","id":1,"result":"0x00000000000000000000000000000000000000000000000000000000000004d2"}
```

Retrieving an element of the map is harder. The position of an element in the map is calculated with:

```js
keccack(LeftPad32(key, 0), LeftPad32(map position, 0))
```

This means to retrieve the storage on pos1\["0x391694e7e0b0cce554cb130d723a9d27458f9298"] we need to calculate the position with:

```js
keccak(
  decodeHex(
    "000000000000000000000000391694e7e0b0cce554cb130d723a9d27458f9298" +
      "0000000000000000000000000000000000000000000000000000000000000001"
  )
)
```

The geth console which comes with the web3 library can be used to make the calculation:

```js
> var key = "000000000000000000000000391694e7e0b0cce554cb130d723a9d27458f9298" + "0000000000000000000000000000000000000000000000000000000000000001"
undefined
> web3.sha3(key, {"encoding": "hex"})
"0x6661e9d6d8b923d5bbaab1b96e1dd51ff6ea2a93520fdc9eb75d059238b8c5e9"
```

Now to fetch the storage:

```js
curl -X POST --data '{"jsonrpc":"2.0", "method": "eth_getStorageAt", "params": ["0x295a70b2de5e3953354a6a8344e616ed314d7251", "0x6661e9d6d8b923d5bbaab1b96e1dd51ff6ea2a93520fdc9eb75d059238b8c5e9", "latest"], "id": 1}' localhost:8545
{"jsonrpc":"2.0","id":1,"result":"0x000000000000000000000000000000000000000000000000000000000000162e"}
```
