DOTNET的加密技术应用

using System;
using System.Text;
using System.Security;
using System.Security.Cryptography;
using System.IO;
namespace EncryptClasses
{
 /// <summary>
 /// 此处定义的是DES加密,为了便于今后的管理和维护
 /// 请不要随便改动密码,或者改变了密码后请一定要
 /// 牢记先前的密码,否则将会照成不可预料的损失
 /// </summary>
 public class DESEncrypt
 {
  #region "member fields"
  private string iv="12345678";
  private string key="12345678";
  private Encoding encoding=new UnicodeEncoding();
  private DES des;
  #endregion
  /// <summary>
  /// 构造函数
  /// </summary>
  public DESEncrypt()
  {
   des=new DESCryptoServiceProvider();
  }
  #region "propertys"
  /// <summary>
  /// 设置加密密钥
  /// </summary>
  public string EncryptKey
  {
   get{return this.key;}
   set
   {
      this.key=value;
   }
  }
  /// <summary>
  /// 要加密字符的编码模式
  /// </summary>
  public Encoding EncodingMode
  {
   get{return this.encoding;}
   set{this.encoding=value;}
  }
  #endregion
  #region "methods"
  /// <summary>
  /// 加密字符串并返回加密后的结果
  /// </summary>
  /// <param name="str"></param>
  /// <returns></returns>
  public string EncryptString(string str)
  {
   byte[] ivb=Encoding.ASCII.GetBytes(this.iv);
   byte[] keyb=Encoding.ASCII.GetBytes(this.EncryptKey);//得到加密密钥
   byte[] toEncrypt=this.EncodingMode.GetBytes(str);//得到要加密的内容
   byte[] encrypted;
   ICryptoTransform encryptor=des.CreateEncryptor(keyb,ivb);
   MemoryStream msEncrypt=new MemoryStream();
   CryptoStream csEncrypt=new CryptoStream(msEncrypt,encryptor,CryptoStreamMode.Write);
   csEncrypt.Write(toEncrypt,0,toEncrypt.Length);
   csEncrypt.FlushFinalBlock();
   encrypted=msEncrypt.ToArray();
   csEncrypt.Close();
   msEncrypt.Close();
   return this.EncodingMode.GetString(encrypted);
  }
  /// <summary>
  /// 加密指定的文件,如果成功返回True,否则false
  /// </summary>
  /// <param name="filePath">要加密的文件路径</param>
  /// <param name="outPath">加密后的文件输出路径</param>
  public void EncryptFile(string filePath,string outPath)
  {
   bool isExist=File.Exists(filePath);
   if(isExist)//如果存在
   {
    byte[] ivb=Encoding.ASCII.GetBytes(this.iv);
    byte[] keyb=Encoding.ASCII.GetBytes(this.EncryptKey);
    //得到要加密文件的字节流
    FileStream fin=new FileStream(filePath,FileMode.Open,FileAccess.Read);
    StreamReader reader=new StreamReader(fin,this.EncodingMode);
    string dataStr=reader.ReadToEnd();
    byte[] toEncrypt=this.EncodingMode.GetBytes(dataStr);
    fin.Close();

    FileStream fout=new FileStream(outPath,FileMode.Create,FileAccess.Write);
    ICryptoTransform encryptor=des.CreateEncryptor(keyb,ivb);
    CryptoStream csEncrypt=new CryptoStream(fout,encryptor,CryptoStreamMode.Write);
    try
    {
     //加密得到的文件字节流
     csEncrypt.Write(toEncrypt,0,toEncrypt.Length);
     csEncrypt.FlushFinalBlock();
    }
    catch(Exception err)
    {
     throw new ApplicationException(err.Message);
    }
    finally
    {
     try
     {
      fout.Close();
      csEncrypt.Close();
     }
     catch
     {
      ;
     }
    }
   }
   else
   {
    throw new FileNotFoundException("没有找到指定的文件");
   }
  }
  /// <summary>
  /// 文件加密函数的重载版本,如果不指定输出路径,
  /// 那么原来的文件将被加密后的文件覆盖
  /// </summary>
  /// <param name="filePath"></param>
  public void EncryptFile(string filePath)
  {
   this.EncryptFile(filePath,filePath);
  }

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