MD5的全称是Message-Digest Algorithm 5(信息-摘要算法)，在90年代初由MIT Laboratory for Computer Science和RSA Data Security Inc的Ronald L. Rivest开发出来，经MD2、MD3和MD4发展而来。

是让大容量信息在用签署私人密匙前被"压缩"成一种保密的格式(就是把一个任意长度的字节串变换成一定长的大整数)。不管是MD2、MD4还是MD5，它们都需要获得一个随机长度的信息并产生一个128位的信息摘要。虽然这些算法的结构或多或少有些相似，但MD2的设计与MD4和MD5完全不同，那是因为MD2是为8位机器做过设计优化的，而MD4和MD5却是面向32位的电脑。

1.新建一个窗体应用程序

有三种方式来加密，上两种注释的是不需要秘钥加密的，下一种是是需要秘钥和向量的；

代码如下：

 

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Globalization;using System.IO;using System.Linq;using System.Security.Cryptography;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace AES加密解密{    public partial class MD5_DES_加密解密 : Form    {        public MD5_DES_加密解密()        {            InitializeComponent();        }        private void MD5_DES_加密解密_Load(object sender, EventArgs e)        {        }        /// 
        /// 32位MD5加密        /// 
        ///         ///         /*  private void button1_Click(object sender, EventArgs e)          {//这两种方式都可以              /*  byte[] result = Encoding.Default.GetBytes(this.textBox1.Text.Trim());    //textBox1为输入密码的文本框                MD5 md5 = new MD5CryptoServiceProvider();                byte[] output = md5.ComputeHash(result);                this.richTextBox1.Text = BitConverter.ToString(output).Replace("-", "");  //richTextBox1为输出加密文本的文本框           */        /*  if (richTextBox1.Text!=null)         {             richTextBox1.Text = "";             string str = textBox1.Text;             MD5 md = MD5.Create();             byte[] bytes = md.ComputeHash(System.Text.Encoding.UTF8.GetBytes(str));             foreach (byte b in bytes)             {                 richTextBox1.Text += b.ToString();             }         }     }*/        private void button1_Click(object sender, EventArgs e)        {
    //加密-此种方法要输入秘钥键值            richTextBox1.Text = Encode(textBox1.Text, textBox2.Text, textBox3.Text);        }        private void button2_Click(object sender, EventArgs e)        {
    //解密-此种方法要输入秘钥键值            richTextBox1.Text = Decode(textBox4.Text, textBox2.Text, textBox3.Text);        }               //加密        public static string Encode(string data, string Key_64, string Iv_64)        {            string KEY_64 = Key_64;// "VavicApp";            string IV_64 = Iv_64;// "VavicApp";//64位的键值和IV值要为8位            try            {                byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64);                byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64);                DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();                int i = cryptoProvider.KeySize;                MemoryStream ms = new MemoryStream();                CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateEncryptor(byKey, byIV), CryptoStreamMode.Write);                StreamWriter sw = new StreamWriter(cst);                sw.Write(data);                sw.Flush();                cst.FlushFinalBlock();                sw.Flush();                return Convert.ToBase64String(ms.GetBuffer(), 0, (int)ms.Length);            }            catch (Exception x)            {                return x.Message;            }        }        //解密        public static string Decode(string data, string Key_64, string Iv_64)        {            string KEY_64 = Key_64;// "VavicApp";密钥            string IV_64 = Iv_64;// "VavicApp"; 向量IV必须是 8 字节长度的十六进制数。            try            {                byte[] byKey = System.Text.ASCIIEncoding.ASCII.GetBytes(KEY_64);                byte[] byIV = System.Text.ASCIIEncoding.ASCII.GetBytes(IV_64);                byte[] byEnc;                byEnc = Convert.FromBase64String(data); //把需要解密的字符串转为8位无符号数组                DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();                MemoryStream ms = new MemoryStream(byEnc);                CryptoStream cst = new CryptoStream(ms, cryptoProvider.CreateDecryptor(byKey, byIV), CryptoStreamMode.Read);                StreamReader sr = new StreamReader(cst);                return sr.ReadToEnd();            }            catch (Exception x)            {                return x.Message;            }        }    }}

2.实验效果