> For the complete Linea documentation index, see [llms.txt](/llms.txt). > Agents can fetch this page as Markdown at [https://docs.linea.build/reference/smart-contracts/lib/utils.md](https://docs.linea.build/reference/smart-contracts/lib/utils.md). # Utils # `Utils` ### _efficientKeccak ```solidity function _efficientKeccak(bytes32 _left, bytes32 _right) internal pure returns (bytes32 value) ``` Performs a gas optimized keccak hash for two bytes32 values. #### Parameters | Name | Type | Description | | --- | --- | --- | | _left | bytes32 | Left value. | | _right | bytes32 | Right value. | ### _efficientKeccak ```solidity function _efficientKeccak(uint256 _left, address _right) internal pure returns (bytes32 value) ``` Performs a gas optimized keccak hash for uint256 and address. #### Parameters | Name | Type | Description | | --- | --- | --- | | _left | uint256 | Left value. | | _right | address | Right value. |