请教一个加密问题。

密码用md5加密后，放到数据库中。
等这个用户再次登陆时，把他输入的密码再次用相同方法的md5加密，然后和数据库中的比较，如果相同，说明密码正确，否则不正确。这样做的目的是后台不知道用户的真正密码是什么。因为md5是不可逆的

我通常适应对称加密算法参看Rijndael
_______
MD5通常用来验证完整性而不是加密

string 加密密码 = System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(密码,"md5");

ms-help://MS.MSDNQTR.v80.chs/MS.MSDN.v80/MS.NETDEVFX.v20.chs/cpref11/html/T_System_Security_Cryptography_MD5.htm

using System;
using System.Text;namespace ICR.Security
{
/// <summary>
/// Base64
/// </summary>
public class Base64_
{
public Base64_()
{
}

//code_type取值:UTF-16LE,UTF-16BE,windows-1252,UTF-7,UTF-8,ASCII,GB18030
/// <summary>
/// 编码
/// </summary>
public string encodebase64(string code_type,string code)
{
string encode = "";
byte[] bytes = Encoding.GetEncoding(code_type).GetBytes(code);
try
{
encode = Convert.ToBase64String(bytes);
}
catch
{
encode = code;
}
return encode;
} /// <summary>
/// 解码
/// </summary>
public string decodebase64(string code_type,string code)
{
string decode = "";
byte[] bytes = Convert.FromBase64String(code);
try
{
decode = Encoding.GetEncoding(code_type).GetString(bytes);
}
catch
{
decode = code;
}
return decode;
}
}
}

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;namespace ICR.Security
{
    /// <summary>
    /// DES
    /// </summary>
    public class DES_
    {
        private DES mydes;
        public string Key;
        public string IV;
        /// <summary>
        /// 对称加密类的构造函数        /// </summary>
        public DES_(string key)
        {
            mydes = new DESCryptoServiceProvider();
            Key = key;
            IV="728#$$%^TyguyshdsufhsfwofnhKJHJKHIYhfiusf98*(^%$^&&(*&()$##@%%$RHGJJHHJ";
        }
        /// <summary>
        /// 对称加密类的构造函数        /// </summary>
        public DES_(string key, string iv)
        {
            mydes = new DESCryptoServiceProvider();
            Key = key;
            IV = iv;
        }
        /// <summary>
        /// 获得密钥
        /// </summary>
        /// <returns>密钥</returns>
        private byte[] GetLegalKey()
        {
            string sTemp = Key;
            mydes.GenerateKey();
            byte[] bytTemp = mydes.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 = IV;
            mydes.GenerateIV();
            byte[] bytTemp = mydes.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 Encrypt(string Source)
        {
            try
            {
                byte[] bytIn = UTF8Encoding.UTF8.GetBytes(Source);
                MemoryStream ms = new MemoryStream();
                mydes.Key = GetLegalKey();
                mydes.IV = GetLegalIV();
                ICryptoTransform encrypto = mydes.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);
            }
            catch (Exception ex)
            {
                throw new Exception("在文件加密的时候出现错误！错误提示： \n" + ex.Message);
            }
        }

/// <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 Decrypt(string Source)
        {
            try
            {
                byte[] bytIn = Convert.FromBase64String(Source);
                MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
                mydes.Key = GetLegalKey();
                mydes.IV = GetLegalIV();
                ICryptoTransform encrypto = mydes.CreateDecryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
                StreamReader sr = new StreamReader(cs);
                return sr.ReadToEnd();
            }
            catch (Exception ex)
            {
                throw new Exception("在文件解密的时候出现错误！错误提示： \n" + ex.Message);
            }
        }
        /// <summary>
        /// 加密方法byte[] to byte[]
        /// </summary>
        /// <param name="Source">待加密的byte数组</param>
        /// <returns>经过加密的byte数组</returns>
        public byte[] Encrypt(byte[] Source)
        {
            try
            {
                byte[] bytIn = Source;
                MemoryStream ms = new MemoryStream();
                mydes.Key = GetLegalKey();
                mydes.IV = GetLegalIV();
                ICryptoTransform encrypto = mydes.CreateEncryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
                cs.Write(bytIn, 0, bytIn.Length);
                cs.FlushFinalBlock();
                ms.Close();
                byte[] bytOut = ms.ToArray();
                return bytOut;
            }
            catch (Exception ex)
            {
                throw new Exception("在文件加密的时候出现错误！错误提示： \n" + ex.Message);
            }
        }
        /// <summary>
        /// 解密方法byte[] to byte[]
        /// </summary>
        /// <param name="Source">待解密的byte数组</param>
        /// <returns>经过解密的byte数组</returns>
        public byte[] Decrypt(byte[] Source)
        {
            try
            {
                byte[] bytIn = Source;
                MemoryStream ms = new MemoryStream(bytIn, 0, bytIn.Length);
                mydes.Key = GetLegalKey();
                mydes.IV = GetLegalIV();
                ICryptoTransform encrypto = mydes.CreateDecryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
                StreamReader sr = new StreamReader(cs);
                return UTF8Encoding.UTF8.GetBytes(sr.ReadToEnd());
            }
            catch (Exception ex)
            {
                throw new Exception("在文件解密的时候出现错误！错误提示： \n" + ex.Message);
            }
        }
        /// <summary>
        /// 加密方法File to File
        /// </summary>
        /// <param name="inFileName">待加密文件的路径</param>
        /// <param name="outFileName">待加密后文件的输出路径</param>

        public void Encrypt(string inFileName, string outFileName)
        {
            try
            {                FileStream fin = new FileStream(inFileName, FileMode.Open, FileAccess.Read);
                FileStream fout = new FileStream(outFileName, FileMode.OpenOrCreate, FileAccess.Write);
                fout.SetLength(0);                mydes.Key = GetLegalKey();
                mydes.IV = GetLegalIV();                byte[] bin = new byte[100];
                long rdlen = 0;
                long totlen = fin.Length;
                int len;                                     ICryptoTransform encrypto = mydes.CreateEncryptor();
                CryptoStream cs = new CryptoStream(fout, encrypto, CryptoStreamMode.Write);
                while (rdlen < totlen)
                {
                    len = fin.Read(bin, 0, 100);
                    cs.Write(bin, 0, len);
                    rdlen = rdlen + len;
                }
                cs.Close();
                fout.Close();
                fin.Close();                }
            catch (Exception ex)
            {
                throw new Exception("在文件加密的时候出现错误！错误提示： \n" + ex.Message);
            }
        }
        /// <summary>
        /// 解密方法File to File
        /// </summary>
        /// <param name="inFileName">待解密文件的路径</param>
        /// <param name="outFileName">待解密后文件的输出路径</param>
        public void Decrypt(string inFileName, string outFileName)
        {
            try
            {
                FileStream fin = new FileStream(inFileName, FileMode.Open, FileAccess.Read);
                FileStream fout = new FileStream(outFileName, FileMode.OpenOrCreate, FileAccess.Write);
                fout.SetLength(0);                byte[] bin = new byte[100];
                long rdlen = 0;
                long totlen = fin.Length;
                int len;
                mydes.Key = GetLegalKey();
                mydes.IV = GetLegalIV();
                ICryptoTransform encrypto = mydes.CreateDecryptor();
                CryptoStream cs = new CryptoStream(fout, encrypto, CryptoStreamMode.Write);
                while (rdlen < totlen)
                {
                    len = fin.Read(bin, 0, 100);
                    cs.Write(bin, 0, len);
                    rdlen = rdlen + len;
                }
                cs.Close();
                fout.Close();
                fin.Close();                }
            catch (Exception ex)
            {
                throw new Exception("在文件解密的时候出现错误！错误提示： \n" + ex.Message);
            }
        }    }
}

调试易

请教一个加密问题。

解决方案 »