0x20 range - crypto
function (runState) {
    const [offset, length] = runState.stack.popN(2)
    subMemUsage(runState, offset, length)
    let data = Buffer.alloc(0)
    if (!length.isZero()) {
      data = runState.memory.read(offset.toNumber(), length.toNumber())
    }
    // copy fee
    subGas(runState, new BN(runState._common.param('gasPrices', 'sha3Word')).imul(length.divCeil(new BN(32))))
    const r = new BN(utils.keccak256(data))
    runState.stack.push(r)
  }