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eth_getStorageAt

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

Parameters

  • address: [Required] A string representing the address (20 bytes) of the storage.
  • storage position: [Required] A hexadecimal code of the position in the storage.
  • block parameter: [Required] A hexadecimal block number, or one of the string tags latest, earliest, pending, safe, or finalized. See the default block parameter.

Returns

storage value: A hexadecimal equivalent of the integer indicating the value of the storage position at the provided address.

Example

Replace YOUR-API-KEY with an API key from your Infura dashboard.

Request

curl https://optimism-mainnet.infura.io/v3/YOUR-API-KEY \
-X POST \
-H "Content-Type: application/json" \
-d '{"jsonrpc": "2.0", "method": "eth_getStorageAt", "params": ["0x295a70b2de5e3953354a6a8344e616ed314d7251", "0x6661e9d6d8b923d5bbaab1b96e1dd51ff6ea2a93520fdc9eb75d059238b8c5e9", "0x65a8db"], "id": 1}'

Response

{
"jsonrpc": "2.0",
"id": 1,
"result": "0x0000000000000000000000000000000000000000000000000000000000000000"
}

Additional notes

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() public {
pos0 = 1234;
pos1[msg.sender] = 5678;
}
}

Retrieving the value of pos0 is straight forward:

curl https://mainnet.infura.io/v3/YOUR-API-KEY \
-X POST \
-H "Content-Type: application/json" \
-d '{"jsonrpc": "2.0", "method": "eth_getStorageAt", "params": ["0x295a70b2de5e3953354a6a8344e616ed314d7251", "0x0", "0x65a8db"], "id": 1}'
{
"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:

keccak(LeftPad32(key, 0), LeftPad32(map position, 0))

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

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

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

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

Now to fetch the storage:

curl https://mainnet.infura.io/v3/YOUR-PROJECT-ID \
-X POST \
-H "Content-Type: application/json" \
-d '{"jsonrpc": "2.0", "method": "eth_getStorageAt", "params": ["0x295a70b2de5e3953354a6a8344e616ed314d7251", "0x6661e9d6d8b923d5bbaab1b96e1dd51ff6ea2a93520fdc9eb75d059238b8c5e9", "0x65a8db"], "id": 1}'
{
"jsonrpc": "2.0",
"id": 1,
"result": "0x000000000000000000000000000000000000000000000000000000000000162e"
}