CRC16加密算法

1、CRC16(Modbus，多项式为0x8005)的Java实现：

        

public int getCrc16_Modbus(byte[] data) {
    int crc = 0xFFFF;
    int POLYNOMIAL = 0xA001;
    for (byte b : data) {
        crc ^= b & 0xFF;
        for (int i = 0; i < 8; i++) {
            if ((crc & 1) == 1) {
                crc = (crc >>> 1) ^ POLYNOMIAL;
            } else {
                crc = crc >>> 1;
            }
        }
    }
    return crc;
}

2、CRC16(CCITT-FALSE，多项式0x1021)的Java实现：

public int getCrc16CCITT_False(byte[] bytes) {
    int crc = 0xffff; // initial value
    int polynomial = 0x1021; // poly value
    for (int index = 0; index < bytes.length; index++) {
        byte b = bytes[index];
        for (int i = 0; i < 8; i++) {
            boolean bit = ((b >> (7 - i) & 1) == 1);
            boolean c15 = ((crc >> 15 & 1) == 1);
            crc <<= 1;
            if (c15 ^ bit)
                crc ^= polynomial;
        }
    }
    crc &= 0xffff;
    return crc;
}