对称算法SymmetricAlgorithm的抽象基类实现带私钥的加密/解密算法的封装类

程序编辑当中安全是比较重要的，很多文件我们需要进行加密才能确保其安全，现在流行的加密就是md5加密，md5加密虽说是不可逆的，但是现在网上有专破解md5的机构，使得md5不再安全。

其实我们可以利用对称算法SymmetricAlgorithm的抽象基类实现带私钥的加密/解密算法。例如：我们可以对数据库连接字符串进行加密，即使我们的程序有漏洞，黑客侵入到源码服务器，但是我们的数据库字符串是加密的，黑客也无法得到数据库连接地址，这就不能够修改数据库信息。

下面提供对称算法SymmetricAlgorithm的抽象基类实现带私钥的加密/解密算法的封装类,把代码复制，命名cs文件名为：conn.cs。

/*开始
using System.Collections;
using System.Configuration;
using System.Web.UI.HtmlControls;
using System.Security.Cryptography;
using System.Text.RegularExpressions;

namespace chat.comm
{
    /// <summary>
    /// 数据库连接加密解密程序
    /// </summary>
    public class conn
    {
        private SymmetricAlgorithm mobjCryptoService;
        private string DecKey;
        private string DecIV;
        public conn()
        {
            mobjCryptoService = new RijndaelManaged();
            DecKey = "asdfsdfsdf534534543*(&(^)(*(*)/KVwgPDwDhEB1c2qPEQOuUI7Wxu/Lh%(HilFiqWr4uJ$j!y6&(*jkP87jH7";
            DecIV = "JKHJLJK(*&^&)&HKLJKLJL$NauRU7cEQjADEewXXQxJW(u%g6HJ($jh7&!hg4ui%$hjk";
        }

        /// <summary>
        /// 获得数据库连接
        /// </summary>
        /// <returns>数据库连接字符串</returns>
        public string GetConnString()
        {
            string getConnectionString = ConfigurationSettings.AppSettings["ConnString"];
            string strConn = Decrypto(getConnectionString);
            return strConn;
        }

        /// <summary>
        /// 加密数据库连接
        /// </summary>
        /// <returns>加密数据库连接字符串</returns>
        public string EnGetConnString()
        {
            string getConnectionString = ConfigurationSettings.AppSettings["ConnString"];
            string strConn = Encrypto(getConnectionString);
            return strConn;
        }

        /// <summary>
        /// 获得密钥
        /// </summary>
        /// <returns>密钥</returns>
        private byte[] GetLegalKey()
        {
            string sTemp = DecKey;
            mobjCryptoService.GenerateKey();
            byte[] bytTemp = mobjCryptoService.Key;
            int KeyLength = bytTemp.Length;
            if (sTemp.Length > KeyLength)
                sTemp = sTemp.Substring(0, KeyLength);
            else if (sTemp.Length < KeyLength)
                sTemp = sTemp.PadRight(KeyLength, ' ');
            return ASCIIEncoding.ASCII.GetBytes(sTemp);
        }

        /// <summary>
        /// 获得初始向量IV
        /// </summary>
        /// <returns>初试向量IV</returns>
        private byte[] GetLegalIV()
        {
            string sTemp = DecIV;
            mobjCryptoService.GenerateIV();
            byte[] bytTemp = mobjCryptoService.IV;
            int IVLength = bytTemp.Length;
            if (sTemp.Length > IVLength)
                sTemp = sTemp.Substring(0, IVLength);
            else if (sTemp.Length < IVLength)
                sTemp = sTemp.PadRight(IVLength, ' ');
            return ASCIIEncoding.ASCII.GetBytes(sTemp);
        }

        /// <summary>
        /// 加密方法
        /// </summary>
        /// <param name="Source">待加密的串</param>
        /// <returns>经过加密的串</returns>
        public string Encrypto(string Source)
        {
            byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
            MemoryStream ms = new MemoryStream();
            mobjCryptoService.Key = GetLegalKey();
            mobjCryptoService.IV = GetLegalIV();
            ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
            cs.Write(bytIn, 0, bytIn.Length);
            cs.FlushFinalBlock();
            ms.Close();
            byte[] bytOut = ms.ToArray();
            return Convert.ToBase64String(bytOut);
        }
        /// <summary>
        /// 解密方法
        /// </summary>
        /// <param name="Source">待解密的串</param>
        /// <returns>经过解密的串</returns>
        public string Decrypto(string Source)
        {
            byte[] bytIn = Convert.FromBase64String(Source);
            MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
            mobjCryptoService.Key = GetLegalKey();
            mobjCryptoService.IV = GetLegalIV();
            ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
            StreamReader sr = new StreamReader(cs);
            return sr.ReadToEnd();
        }
    }
}

/*结束

例如我们要对数据库连接字符串加密：Data Source=RGGF-9265FDC038\SQL2000;User ID=sa;Password=sa123456。
调用conn.cs代码为：string connStr = new conn().EnGetConnString()，把加密后的字符串放到web.config当中。程序中需要调用数据库连接字符串的时候，只需解密就可以了：string connStr = new conn().GetConnString()，