connectionString加密

首先是加密，解密类。

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace SqlConnectionEncryp
{
    public class Encrypt
    {
        /// <summary>
        ///  MD5加密
        /// </summary>
        public static string MD5Encrypt(string Text, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] inputByteArray = Encoding.Default.GetBytes(Text);
            des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(, ));
            des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(, ));
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, , inputByteArray.Length);
            cs.FlushFinalBlock();
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }
            return ret.ToString();
        }

        /// <summary>
        ///  MD5解密
        /// </summary>
        public static string MD5Decrypt(string Text, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            int len;
            len = Text.Length / ;
            byte[] inputByteArray = new byte[len];
            int x, i;
            for (x = ; x < len; x++)
            {
                i = Convert.ToInt32(Text.Substring(x * , ), );
                inputByteArray[x] = (byte)i;
            }
            des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(, ));
            des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(, ));
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, , inputByteArray.Length);
            cs.FlushFinalBlock();
            return Encoding.Default.GetString(ms.ToArray());
        }

        /// <summary>
        /// TripleDES加密
        /// </summary>
        public static string TripleDESEncrypting(string strSource)
        {
            try
            {
                byte[] bytIn = Encoding.Default.GetBytes(strSource);
                byte[] key = { , , , , , , , , , , , , , , , , , , , , , , ,  }; //定义密钥
                byte[] IV = { , , , , , , ,  };  //定义偏移量
                TripleDESCryptoServiceProvider TripleDES = new TripleDESCryptoServiceProvider();
                TripleDES.IV = IV;
                TripleDES.Key = key;
                ICryptoTransform encrypto = TripleDES.CreateEncryptor();
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
                cs.Write(bytIn, , bytIn.Length);
                cs.FlushFinalBlock();
                byte[] bytOut = ms.ToArray();
                return System.Convert.ToBase64String(bytOut);
            }
            catch (Exception ex)
            {
                throw new Exception("加密时候出现错误!错误提示:\n" + ex.Message);
            }
        }

        /// <summary>
        /// TripleDES解密
        /// </summary>
        public static string TripleDESDecrypting(string Source)
        {
            try
            {
                byte[] bytIn = System.Convert.FromBase64String(Source);
                byte[] key = { , , , , , , , , , , , , , , , , , , , , , , ,  }; //定义密钥
                byte[] IV = { , , , , , , ,  };   //定义偏移量
                TripleDESCryptoServiceProvider TripleDES = new TripleDESCryptoServiceProvider();
                TripleDES.IV = IV;
                TripleDES.Key = key;
                ICryptoTransform encrypto = TripleDES.CreateDecryptor();
                System.IO.MemoryStream ms = new System.IO.MemoryStream(bytIn, , bytIn.Length);
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
                StreamReader strd = new StreamReader(cs, Encoding.Default);
                return strd.ReadToEnd();
            }
            catch (Exception ex)
            {
                throw new Exception("解密时候出现错误!错误提示:\n" + ex.Message);
            }
        }
    }
}

加密使用MD5Decrypt，自己给定一个密钥。下面是对连接字符串加密的界面：

代码和测试效果：

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btnCreate_Click(object sender, EventArgs e)
        {
            if (string.IsNullOrEmpty(txtClear.Text))
            {
                MessageBox.Show("明文不能为空！");
            }
            if (string.IsNullOrEmpty(txtKey.Text))
            {
                MessageBox.Show("密钥不能为空！");
            }

            string strCipher = Encrypt.MD5Encrypt(txtClear.Text, txtKey.Text);
            txtCipher.Text = strCipher;
        }
    }

加密的原因是，为客户开发的某些程序，需要访问公司（我们自己工作的）在公网的数据库，但是我们不能将明文数据库访问字符串，存放在客户的应用程序上，最好的办法就是将其加密。下面就在一个为客户开发的程序中使用这个加密连接。这里，我将密钥和密文都写在了配置文件中。如果用户猜出我的加密算法，他们可以根据密钥，可以轻松获得我的明文。所以，不要傻到直接将密钥配置命名成key。如果将密钥写死在代码中就不方便控制，客户反编译同样能获知加密算法和密钥，从而获得本来的连接字符串。

下面在获取连接字符串时，都要对其进行解密，所以构造一个解密类是必要的。

public class ConfigHelper
    {
        /// <summary>
        /// 获取普通连接
        /// </summary>
        public static string GetConn(string conn)
        {
            return ConfigurationManager.ConnectionStrings[conn].ConnectionString;
        }
        /// <summary>
        /// 获取appsetting
        /// </summary>
        public static string GetAppSetting(string key)
        {
            return ConfigurationManager.AppSettings[key];
        }
        /// <summary>
        /// 获取解密连接
        /// </summary>
        public static string GetConn(string conn, string key)
        {
            string strConn = GetConn(conn);
            string strKey = GetAppSetting(key);
            return MD5Decrypt(strConn, strKey);
        }

        /// <summary>
        ///  MD5解密
        /// </summary>
        private static string MD5Decrypt(string Text, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            int len;
            len = Text.Length / ;
            byte[] inputByteArray = new byte[len];
            int x, i;
            for (x = ; x < len; x++)
            {
                i = Convert.ToInt32(Text.Substring(x * , ), );
                inputByteArray[x] = (byte)i;
            }
            des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(, ));
            des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(, ));
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, , inputByteArray.Length);
            cs.FlushFinalBlock();
            return Encoding.Default.GetString(ms.ToArray());
        }
    }

下面是解密效果，如果客户不是专业人士，我们公网数据库连接就是安全的了：