C# DES 加密/解密

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Security;
using System.Security.Cryptography;
/*----------------------------------------------
 *  DES加密、解密类库，字符串加密结果使用BASE64编码返回，支持文件的加密和解密
 *  作者： Leo.wl
 * ---------------------------------------------
 */
namespace ZU14{ 
      public sealed class DES    
      { 
       string iv = "1234的yzo";        
       string key = "123在yzo";       
       /// <summary>        
       /// DES加密偏移量，必须是>=8位长的字符串        
       /// </summary>        
       public string IV        
       {            
           get { return iv; }            
           set { iv = value; }       
        }        
       /// <summary>        
       /// DES加密的私钥，必须是8位长的字符串        
       /// </summary>        
       public string Key       
       {            
         get { return key; }            
         set { key = value; }       
       }        
       /// <summary>        
       /// 对字符串进行DES加密       
       /// </summary>        
       /// <param name="sourceString">待加密的字符串</param>        
       /// <returns>加密后的BASE64编码的字符串</returns>        
       public string Encrypt(string sourceString)        
       {            
              byte[] btKey = Encoding.Default.GetBytes(key);            
              byte[] btIV = Encoding.Default.GetBytes(iv);            
              DESCryptoServiceProvider des = new DESCryptoServiceProvider();            
              using (MemoryStream ms = new MemoryStream())            
              {                
                   byte[] inData = Encoding.Default.GetBytes(sourceString);              
                    try                
                     {                    
                        using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(btKey, btIV), CryptoStreamMode.Write))                    
                        {   
                            cs.Write(inData, 0, inData.Length); 
                            cs.FlushFinalBlock();                    
                         }                    
                         return Convert.ToBase64String(ms.ToArray());             
                     } 
                      catch{ throw;}            
               }       
              }        
              /// <summary>        
              /// 对DES加密后的字符串进行解密        
              /// </summary>        
              /// <param name="encryptedString">待解密的字符串</param>        
              /// <returns>解密后的字符串</returns>        
              public string Decrypt(string encryptedString)        
              {            
                 byte[] btKey = Encoding.Default.GetBytes(key);            
                 byte[] btIV = Encoding.Default.GetBytes(iv);            
                 DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                  using (MemoryStream ms = new MemoryStream())            
                  {                
                     byte[] inData = Convert.FromBase64String(encryptedString);
                      try {                    
                       using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(btKey, btIV), CryptoStreamMode.Write)) 
                      {                        
                         cs.Write(inData, 0, inData.Length);
                          cs.FlushFinalBlock(); 
                       }                    
                       return Encoding.Default.GetString(ms.ToArray());
                }               
                 catch                
                 { throw;  }           
                }        
               }        
               /// <summary>        
               /// 对文件内容进行DES加密        
               /// </summary>        
               /// <param name="sourceFile">待加密的文件绝对路径</param>
               /// <param name="destFile">加密后的文件保存的绝对路径</param> 
                public void EncryptFile(string sourceFile, string destFile)
                {            
                    if (!File.Exists(sourceFile)) 
                    throw new FileNotFoundException("指定的文件路径不存在！", sourceFile);
                     byte[] btKey = Encoding.Default.GetBytes(key);
                      byte[] btIV = Encoding.Default.GetBytes(iv); 
                     DESCryptoServiceProvider des = new DESCryptoServiceProvider();
                     byte[] btFile = File.ReadAllBytes(sourceFile); 
                     using (FileStream fs = new FileStream(destFile, FileMode.Create, FileAccess.Write))
                    {                
                        try
                         {     
                             using (CryptoStream cs = new CryptoStream(fs, des.CreateEncryptor(btKey, btIV), CryptoStreamMode.Write)) 
                             {                        
                                 cs.Write(btFile, 0, btFile.Length); 
                                 cs.FlushFinalBlock();  
                               }               
                          }catch {    throw;  }  
                          finally {                    fs.Close();                } 
            }        }        
/// <summary>        
/// 对文件内容进行DES加密，加密后覆盖掉原来的文件
        /// </summary>        
/// <param name="sourceFile">待加密的文件的绝对路径</param>        
public void EncryptFile(string sourceFile)        
{           
 EncryptFile(sourceFile, sourceFile);        
}        
/// <summary>        
/// 对文件内容进行DES解密        
/// </summary>        
/// <param name="sourceFile">待解密的文件绝对路径</param>        
/// <param name="destFile">解密后的文件保存的绝对路径</param>        
public void DecryptFile(string sourceFile, string destFile)        
{            
if (!File.Exists(sourceFile)) 
throw new FileNotFoundException("指定的文件路径不存在！", sourceFile);
            byte[] btKey = Encoding.Default.GetBytes(key);
            byte[] btIV = Encoding.Default.GetBytes(iv);
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            byte[] btFile = File.ReadAllBytes(sourceFile);            
using (FileStream fs = new FileStream(destFile, FileMode.Create, FileAccess.Write)) 
{                try                
{                    
using (CryptoStream cs = new CryptoStream(fs, des.CreateDecryptor(btKey, btIV), CryptoStreamMode.Write))
                    {  cs.Write(btFile, 0, btFile.Length);
                        cs.FlushFinalBlock();                    
}                }                
catch               
 {                    throw;                }
                finally                
{                    fs.Close();                }            }        }       
 /// <summary>        
/// 对文件内容进行DES解密，加密后覆盖掉原来的文件       
 /// </summary>        
/// <param name="sourceFile">待解密的文件的绝对路径</param>        
public void DecryptFile(string sourceFile)       
 {            DecryptFile(sourceFile, sourceFile);        }    
}} 
 
使用实例：
ZU14.DES des = new ZU14.DES();des.IV = "abcd哈哈笑";des.Key = "必须八位";string es = des.Encrypt("在");Console.WriteLine(es);Console.Write(des.Decrypt(es));des.EncryptFile(@"d:\a.txt", @"d:\b.txt");des.DecryptFile(@"d:\b.txt");Console.ReadKey(true);