MD5即Message-Digest Algorithm 5（信息-摘要算法 5），用于确保信息传输完整一致。是计算机广泛使用的杂凑算法之一（又译摘要算法、哈希算法），主流编程语言普遍已有MD5实现。

　　将数据（如汉字）运算为另一固定长度值是杂凑算法的基础原理，MD5的前身有MD2、MD3和MD4。-MD5 or Message-Digest Algorithm 5 (Information- Digest Algorithm 5), used to ensure a complete and consistent information transfer. Widely used computer, one of hash algorithms (also translated digest algorithm, hash algorithm), mainstream programming languages have generally MD5 implementation. The data (such as Chinese characters) operator to another fixed-length hash value is the basis of principle of the algorithm, MD5' s predecessor are MD2, MD3, and MD4.