pragma solidity 0.4.24;


contract StorageDemo {
  mapping(bytes32 => string) public data;

  event DataStored(
    address user,
    bytes32 key
  );

  function setData(
    string _data
  )
    external
  {
    bytes32 _key = keccak256(abi.encodePacked(_data));
    data[_key] = _data;

    emit DataStored(msg.sender, _key);
  }
}