说明：  使用md5校驗和算法保護文件 通俗的說，就是為保證數據的完整性，用一種指定的算法對原始數據計算出的一個校驗值。接收方用同樣的算法計算一次校驗值，如果和隨數據提供的校驗值一樣，就說明數據是完整的。
(Md5 checksum algorithm used to protect documents that popular, that is, in order to ensure the integrity of the data, using a specified algorithm to the raw data to calculate a checksum. Receiver use the same algorithm for calculating a checksum value, if and as the data provided by the same checksum, they note the data is incomplete.)