code: private void xor(byte[] data, byte[] kdfOut, int dOff, int dRemaining) {
  		for (int i = 0; i != dRemaining; i++) {
  			data[dOff + i] ^= kdfOut[i];
  		}
  	}
docs: 异或
  
  @param data 数据
  @param kdfOut kdf输出值
  @param dOff d偏移
  @param dRemaining d剩余