.NET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);
  }
  /// <summary>
  /// 解密给定的字符串
  /// </summary>
  /// <param name="str">要解密的字符</param>
  /// <returns></returns>
  public string DecryptString(string str)
  {
   byte[] ivb=Encoding.ASCII.GetBytes(this.iv);
   byte[] keyb=Encoding.ASCII.GetBytes(this.EncryptKey);
   byte[] toDecrypt=this.EncodingMode.GetBytes(str);
   byte[] deCrypted=new byte[toDecrypt.Length];
   ICryptoTransform deCryptor=des.CreateDecryptor(keyb,ivb);
   MemoryStream msDecrypt=new MemoryStream(toDecrypt);
   CryptoStream csDecrypt=new CryptoStream(msDecrypt,deCryptor,CryptoStreamMode.Read);
   try
   {
    csDecrypt.Read(deCrypted,0,deCrypted.Length);
   }
   catch(Exception err)
   {
    throw new ApplicationException(err.Message);
   }
   finally
   {
    try
    {
     msDecrypt.Close();
     csDecrypt.Close();
    }
    catch{;}
   }
   return this.EncodingMode.GetString(deCrypted);
  }
  /// <summary>
  /// 解密指定的文件
  /// </summary>
  /// <param name="filePath">要解密的文件路径</param>
  /// <param name="outPath">解密后的文件输出路径</param>
  public void DecryptFile(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);
    FileInfo file=new FileInfo(filePath);
    byte[] deCrypted=new byte[file.Length];
    //得到要解密文件的字节流
    FileStream fin=new FileStream(filePath,FileMode.Open,FileAccess.Read);
    //解密文件
    try
    {
     ICryptoTransform decryptor=des.CreateDecryptor(keyb,ivb);
     CryptoStream csDecrypt=new CryptoStream(fin,decryptor,CryptoStreamMode.Read);
     csDecrypt.Read(deCrypted,0,deCrypted.Length);
    }
    catch(Exception err)
    {
     throw new ApplicationException(err.Message);
    }
    finally
    {
     try
     {
      fin.Close();
     }
     catch{;}
    }
    FileStream fout=new FileStream(outPath,FileMode.Create,FileAccess.Write);
    fout.Write(deCrypted,0,deCrypted.Length);
    fout.Close();
   }
   else
   {
    throw new FileNotFoundException("指定的解密文件没有找到");
   }
  }
  /// <summary>
  /// 解密文件的重载版本,如果没有给出解密后文件的输出路径,
  /// 则解密后的文件将覆盖先前的文件
  /// </summary>
  /// <param name="filePath"></param>
  public void DecryptFile(string filePath)
  {
   this.DecryptFile(filePath,filePath);
  }
  #endregion
 }
 /// <summary>
 /// MD5加密类,注意经MD5加密过的信息是不能转换回原始数据的
 /// ,请不要在用户敏感的信息中使用此加密技术,比如用户的密码,
 /// 请尽量使用对称加密
 /// </summary>
 public class MD5Encrypt
 {
  private MD5 md5;
  public MD5Encrypt()
  {
   md5=new MD5CryptoServiceProvider();
  }
  /// <summary>
  /// 从字符串中获取散列值
  /// </summary>
  /// <param name="str">要计算散列值的字符串</param>
  /// <returns></returns>
  public string GetMD5FromString(string str)
  {
   byte[] toCompute=Encoding.Unicode.GetBytes(str);
   byte[] hashed=md5.ComputeHash(toCompute,0,toCompute.Length);
   return Encoding.ASCII.GetString(hashed);
  }
  /// <summary>
  /// 根据文件来计算散列值
  /// </summary>
  /// <param name="filePath">要计算散列值的文件路径</param>
  /// <returns></returns>
  public string GetMD5FromFile(string filePath)
  {
   bool isExist=File.Exists(filePath);
   if(isExist)//如果文件存在
   {
    FileStream stream=new FileStream(filePath,FileMode.Open,FileAccess.Read);
    StreamReader reader=new StreamReader(stream,Encoding.Unicode);
    string str=reader.ReadToEnd();
    byte[] toHash=Encoding.Unicode.GetBytes(str);
    byte[] hashed=md5.ComputeHash(toHash,0,toHash.Length);
    stream.Close();
    return Encoding.ASCII.GetString(hashed);
   }
   else//文件不存在
   {
    throw new FileNotFoundException("指定的文件没有找到");
   }
  }
 }
 /// <summary>
 /// 用于数字签名的hash类
 /// </summary>
 public class MACTripleDESEncrypt
 {
  private MACTripleDES mact;
  private string __key="ksn168ch";
  private byte[] __data=null;
  public MACTripleDESEncrypt()
  {
   mact=new MACTripleDES();
  }
  /// <summary>
  /// 获取或设置用于数字签名的密钥
  /// </summary>
  public string Key
  {
   get{return this.__key;}
   set
   {
    int keyLength=value.Length;
    int[] keyAllowLengths=new int[]{8,16,24};
    bool isRight=false;
    foreach(int i in keyAllowLengths)
    {
     if(keyLength==keyAllowLengths[i])
     {
      isRight=true;
      break;
     }
    }
    if(!isRight)
     throw new ApplicationException("用于数字签名的密钥长度必须是8,16,24值之一");
    else
     this.__key=value;
   }
  }
  /// <summary>
  /// 获取或设置用于数字签名的用户数据
  /// </summary>
  public byte[] Data
  {
   get{return this.__data;}
   set{this.__data=value;}
  }
  /// <summary>
  /// 得到签名后的hash值
  /// </summary>
  /// <returns></returns>
  public string GetHashValue()
  {
   if(this.Data==null)
    throw new NotSetSpecialPropertyException("没有设置要进行数字签名的用户"+
                                         "数据(property:Data)");
   byte[] key=Encoding.ASCII.GetBytes(this.Key);
   this.mact.Key=key;
   byte[] hash_b=this.mact.ComputeHash(this.mact.ComputeHash(this.Data));
   return Encoding.ASCII.GetString(hash_b);
  }
 }
}