CRC是由待傳輸的資料區塊計算出的，它的計算方式是將待傳輸的區塊視為一堆連續位元所構成的一整個數值，並將此數值除以一特定的除數，通常以二進位表示，此除數又稱為衍生多項式 (Generation Polynomial)，該除數一般皆由設計硬體或軟體的廠商所提供，而除數值位元數目則視欲得到的 CRC 位元數目而定。-CRC is transmitted by the data block to be calculated, which is calculated by the block to be transmitted as a continuous bit composed of a bunch of a whole value and this value divided by a particular divisor, usually binary, said that this division is also known as derivative polynomial (Generation　Polynomial), the divisor rests general hardware or software design provided by the manufacturers, while the number of inter-bit value as the CRC bits to yield a depending on the number.