这个C#类封装的DES加密解密，可以使用默认秘钥进行加密、解密，也可以自定义秘钥进行加密、解密，调用简单方便。

示例一：

using System;
using System.Security.Cryptography; 
using System.Text;
namespace DotNet.Utilities
{
  /// <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,"sharejs.com");
    }
    /// <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,"sharejs.com");
    }
    /// <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
  
  
  }
}

示例二：

///<summary><![CDATA[加密解密帮助类]]></summary> 
  public class Help_Encrypt 
  { 
  
    ///<summary><![CDATA[字符串DES加密函数]]></summary> 
    ///<param name="str"><![CDATA[被加密字符串 ]]></param> 
    ///<param name="key"><![CDATA[密钥 ]]></param>  
    ///<returns><![CDATA[加密后字符串]]></returns>   
    public static string Encode(string str, string key) 
    { 
      try
      { 
        DESCryptoServiceProvider provider = new DESCryptoServiceProvider(); 
        provider.Key = Encoding.ASCII.GetBytes(key.Substring(0, 8)); 
        provider.IV = Encoding.ASCII.GetBytes(key.Substring(0, 8)); 
        byte[] bytes = Encoding.GetEncoding("GB2312").GetBytes(str); 
        MemoryStream stream = new MemoryStream(); 
        CryptoStream stream2 = new CryptoStream(stream, provider.CreateEncryptor(), CryptoStreamMode.Write); 
        stream2.Write(bytes, 0, bytes.Length); 
        stream2.FlushFinalBlock(); 
        StringBuilder builder = new StringBuilder(); 
        foreach (byte num in stream.ToArray()) 
        { 
          builder.AppendFormat("{0:X2}", num); 
        } 
        stream.Close(); 
        return builder.ToString(); 
      } 
      catch (Exception) { return "xxxx"; } 
    } 
    ///<summary><![CDATA[字符串DES解密函数]]></summary> 
    ///<param name="str"><![CDATA[被解密字符串 ]]></param> 
    ///<param name="key"><![CDATA[密钥 ]]></param>  
    ///<returns><![CDATA[解密后字符串]]></returns>   
    public static string Decode(string str, string key) 
    { 
      try
      { 
        DESCryptoServiceProvider provider = new DESCryptoServiceProvider(); 
        provider.Key = Encoding.ASCII.GetBytes(key.Substring(0, 8)); 
        provider.IV = Encoding.ASCII.GetBytes(key.Substring(0, 8)); 
        byte[] buffer = new byte[str.Length / 2]; 
        for (int i = 0; i < (str.Length / 2); i++) 
        { 
          int num2 = Convert.ToInt32(str.Substring(i * 2, 2), 0x10); 
          buffer[i] = (byte)num2; 
        } 
        MemoryStream stream = new MemoryStream(); 
        CryptoStream stream2 = new CryptoStream(stream, provider.CreateDecryptor(), CryptoStreamMode.Write); 
        stream2.Write(buffer, 0, buffer.Length); 
        stream2.FlushFinalBlock(); 
        stream.Close(); 
        return Encoding.GetEncoding("GB2312").GetString(stream.ToArray()); 
      } 
      catch (Exception) { return ""; } 
    } 
  } 
JAVADES加密解密类 
package com.bgxt.messages; 
import java.io.UnsupportedEncodingException; 
import java.security.*; 
import javax.crypto.Cipher; 
import javax.crypto.SecretKey; 
import javax.crypto.SecretKeyFactory; 
import javax.crypto.spec.DESKeySpec;  
import javax.crypto.spec.IvParameterSpec; 
/** 
* 字符串工具集合 
* @author Liudong 
*/
public class StringUtils { 
  
private static final String PASSWORD_CRYPT_KEY = XmlUtil.getConfig().getPasswdKey().substring(0,8);  
//private final static String DES = "DES";  
//private static final byte[] desKey;  
//解密数据   
public static String decrypt(String message,String key) throws Exception {   
      
    byte[] bytesrc =convertHexString(message);    
    Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");     
    DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"));    
    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");    
    SecretKey secretKey = keyFactory.generateSecret(desKeySpec);    
    IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"));   
    cipher.init(Cipher.DECRYPT_MODE, secretKey, iv);      
    byte[] retByte = cipher.doFinal(bytesrc);     
    return new String(retByte);   
}  
public static byte[] encrypt(String message, String key)   
    throws Exception {   
  Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");  
  DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"));  
  SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");   
  SecretKey secretKey = keyFactory.generateSecret(desKeySpec);   
  IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"));   
  cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);  
  return cipher.doFinal(message.getBytes("UTF-8"));   
}  
public static String encrypt(String value){ 
String result=""; 
try{ 
value=java.net.URLEncoder.encode(value, "utf-8");  
result=toHexString(encrypt(value, PASSWORD_CRYPT_KEY)).toUpperCase(); 
}catch(Exception ex){ 
  ex.printStackTrace(); 
  return ""; 
} 
return result;  
} 
public static byte[] convertHexString(String ss)   
{   
byte digest[] = new byte[ss.length() / 2];   
for(int i = 0; i < digest.length; i++)   
{   
String byteString = ss.substring(2 * i, 2 * i + 2);   
int byteValue = Integer.parseInt(byteString, 16);   
digest[i] = (byte)byteValue;   
}   
return digest;   
}   
public static String toHexString(byte b[]) {   
  StringBuffer hexString = new StringBuffer();   
  for (int i = 0; i < b.length; i++) {   
    String plainText = Integer.toHexString(0xff & b[i]);   
    if (plainText.length() < 2)   
      plainText = "0" + plainText;   
    hexString.append(plainText);   
  }    
  return hexString.toString();   
}   
public static void main(String[] args) throws Exception {   
  String value="01";   
  System.out.println("加密数据:"+value);  
  System.out.println("密码为:"+XmlUtil.getConfig().getPasswdKey());  
  String a=encrypt( value);   
  System.out.println("加密后的数据为:"+a);   
}   
}