加密方式：将 明文 +  六位随机码 进行加密

string safeCode = RandSafeCode.RandCode(6, true);string temp = pwd + safeCode;string ciphertext = MD5.GetMD5Upper(temp);

 

生成随机码：

public class RandSafeCode    {        /// 
        /// 生成随机字母与数字        /// 
        /// 生成长度        /// 是否要在生成前将当前线程阻止以避免重复        /// 
              public static string RandCode(int Length, bool Sleep)        {            if (Sleep)                System.Threading.Thread.Sleep(3);            char[] Pattern = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };            string result = "";            int n = Pattern.Length;            System.Random random = new Random(~unchecked((int)DateTime.Now.Ticks));            for (int i = 0; i < Length; i++)            {                int rnd = random.Next(0, n);                result += Pattern[rnd];            }            return result;        }    }

 

加解密：

public class MD5    {        public static string GetMD5Upper(string value)        {            byte[] b = Encoding.Default.GetBytes(value);            b = new MD5CryptoServiceProvider().ComputeHash(b);            string ret = "";            for (int i = 0; i < b.Length; i++)            {                ret += b[i].ToString("X").PadLeft(2, '0');            }            return DesEncrypt(ret);        }         public const string DEFAULT_ENCRYPT_KEY = "1234567890123";        // 
        /// 使用默认加密        /// 
        ///         /// 
              public static string DesEncrypt(string text)        {            if (string.IsNullOrEmpty(text))                return "";            try            {                return DesEncrypt(text, DEFAULT_ENCRYPT_KEY);            }            catch            {                return "";            }        }        public static string DesEncrypt(string strText, string strEncrKey)        {            byte[] byKey = null;            byte[] IV = { 0x22, 0x37, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };            byKey = Encoding.UTF8.GetBytes(strEncrKey.Substring(0, 8));            DESCryptoServiceProvider des = new DESCryptoServiceProvider();            byte[] inputByteArray = Encoding.UTF8.GetBytes(strText);            MemoryStream ms = new MemoryStream();            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(byKey, IV), CryptoStreamMode.Write);            cs.Write(inputByteArray, 0, inputByteArray.Length);            cs.FlushFinalBlock();            return Convert.ToBase64String(ms.ToArray());        }        /// 
        /// 使用默认解密        /// 
        ///         /// 
              public static string DesDecrypt(string cleartext)        {            if (string.IsNullOrEmpty(cleartext))                return "";            try            {                return DesDecrypt(cleartext, DEFAULT_ENCRYPT_KEY);            }            catch            {                return "";            }        }         public static string DesDecrypt(string text, string decrKey)        {            byte[] byKey = null;            byte[] IV = { 0x22, 0x37, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF };            byte[] inputByteArray = new Byte[text.Length];             byKey = Encoding.UTF8.GetBytes(decrKey.Substring(0, 8));            DESCryptoServiceProvider des = new DESCryptoServiceProvider();            inputByteArray = Convert.FromBase64String(text);            MemoryStream ms = new MemoryStream();            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(byKey, IV), CryptoStreamMode.Write);            cs.Write(inputByteArray, 0, inputByteArray.Length);            cs.FlushFinalBlock();            Encoding encoding = new UTF8Encoding();            return encoding.GetString(ms.ToArray());        }    ​}    ​

 

DES是对称密码，是可逆的，要解密时，需要先从数据库取出随机码，所以在保存数据时，要保存密文和随机码

还有其他的对称密码和非对称密码，转一篇文章以便学习

http://www.cnblogs.com/wuhuacong/archive/2010/09/30/1839119.html

文章出处撰写人：伍华聪