ASP.NET----DES加密/解密类

using System;
using System.Security.Cryptography;  
using System.Text;
using System.IO;

/// <summary>
/// DES加密/解密类。
/// </summary>
public class DESEncrypt
{
    public DESEncrypt()
    {
    }

    #region ========加密========

    /// <summary>
    /// 加密
    /// </summary>
    /// <param name="Text"></param>
    /// <returns></returns>
    public static string Encrypt(string Text)
    {
        return Encrypt(Text, "HarryJames");
    }
    /// <summary> 
    /// 加密数据 
    /// </summary> 
    /// <param name="Text"></param> 
    /// <param name="sKey"></param> 
    /// <returns></returns> 
    public static string Encrypt(string Text, string sKey)
    {
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        byte[] inputByteArray;
        inputByteArray = Encoding.Default.GetBytes(Text);
        des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8));
        des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8));
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
        cs.Write(inputByteArray, 0, inputByteArray.Length);
        cs.FlushFinalBlock();
        StringBuilder ret = new StringBuilder();
        foreach (byte b in ms.ToArray())
        {
            ret.AppendFormat("{0:X2}", b);
        }
        return ret.ToString();
    }

    #endregion

    #region ========解密========


    /// <summary>
    /// 解密
    /// </summary>
    /// <param name="Text"></param>
    /// <returns></returns>
    public static string Decrypt(string Text)
    {
        return Decrypt(Text, "HarryJames");
    }
    /// <summary> 
    /// 解密数据 
    /// </summary> 
    /// <param name="Text"></param> 
    /// <param name="sKey"></param> 
    /// <returns></returns> 
    public static string Decrypt(string Text, string sKey)
    {
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        int len;
        len = Text.Length / 2;
        byte[] inputByteArray = new byte[len];
        int x, i;
        for (x = 0; x < len; x++)
        {
            i = Convert.ToInt32(Text.Substring(x * 2, 2), 16);
            inputByteArray[x] = (byte)i;
        }
        des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8));
        des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8));
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
        cs.Write(inputByteArray, 0, inputByteArray.Length);
        cs.FlushFinalBlock();
        return Encoding.Default.GetString(ms.ToArray());
    }

    #endregion
}

public class DESEncryptEx
{
    #region ========加密========
    /// <summary>
    /// 加密字符串
    /// </summary>
    /// <param name="pToEncrypt">待加密字符串</param>
    /// <returns></returns>
    public static string Encrypt(string pToEncrypt)
    {
        byte[] desKey = new byte[] { 0x16, 0x29, 0x98, 0x15, 0x07, 0x08, 0x05, 0x03 };
        byte[] desIV = new byte[] { 0x16, 0x09, 0x14, 0x15, 0x07, 0x08, 0x05, 0x03 };

        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        try
        {
            //把字符串放到byte数组中
            //原来使用的UTF8编码，改成Unicode编码了，不行
            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
            //byte[] inputByteArray=Encoding.Unicode.GetBytes(pToEncrypt);

            //建立加密对象的密钥和偏移量
            //原文使用ASCIIEncoding.ASCII方法的GetBytes方法
            //使得输入密码必须输入英文文本
            des.Key = desKey;		// ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = desIV;			//ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            //Write the byte array into the crypto stream
            //(It will end up in the memory stream)
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();

            //Get the data back from the memory stream, and into a string
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                //Format as hex
                ret.AppendFormat("{0:X2}", b);
            }
            ret.ToString();
            return ret.ToString();
        }
        catch
        {
            return pToEncrypt;
        }
        finally
        {
            des = null;
        }
    }
    #endregion

    #region ========解密========
    /// <summary>
    /// 解密字符串
    /// </summary>
    /// <param name="pToDecrypt">待解密字符串</param>
    /// <returns></returns>
    public static string Decrypt(string pToDecrypt)
    {
        byte[] desKey = new byte[] { 0x16, 0x29, 0x98, 0x15, 0x07, 0x08, 0x05, 0x03 };
        byte[] desIV = new byte[] { 0x16, 0x09, 0x14, 0x15, 0x07, 0x08, 0x05, 0x03 };

        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        try
        {
            //Put the input string into the byte array
            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
            for (int x = 0; x < pToDecrypt.Length / 2; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }

            //建立加密对象的密钥和偏移量，此值重要，不能修改
            des.Key = desKey;			//ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = desIV;				//ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            //Flush the data through the crypto stream into the memory stream
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();

            //Get the decrypted data back from the memory stream
            //建立StringBuild对象，CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象
            StringBuilder ret = new StringBuilder();

            return System.Text.Encoding.Default.GetString(ms.ToArray());
        }
        catch
        {
            return pToDecrypt;
        }
        finally
        {
            des = null;
        }
    }

    #endregion
}

做写入数据库的登录时可以对password进行加密！在数据中显示密码时就是经过加密的字符！当然此类也具备解密功能！只需直接调用即可