用ASP.NET加密Cookie数据(2)

     '标准的DES解密
  
  Public Shared Function Decrypt(ByVal value As String) As String
  
  If value <> "" Then
  
  Dim cryptoProvider As DESCryptoServiceProvider = _
  
  New DESCryptoServiceProvider()
  
  
  '从字符串转换为字节组
  
  Dim buffer As Byte() = Convert.FromBase64String(value)
  
  Dim ms As MemoryStream = New MemoryStream(buffer)
  
  Dim cs As CryptoStream = _
  
  New CryptoStream(ms, cryptoProvider.CreateDecryptor(KEY_64, IV_64), _
  
  CryptoStreamMode.Read)
  
  Dim sr As StreamReader = New StreamReader(cs)
  
  
  Return sr.ReadToEnd()
  
  End If
  
  End Function
  
  
  'TRIPLE DES加密
  
  Public Shared Function EncryptTripleDES(ByVal value As String) As String
  
  If value <> "" Then
  
  Dim cryptoProvider As TripleDESCryptoServiceProvider = _
  
  New TripleDESCryptoServiceProvider()
  
  Dim ms As MemoryStream = New MemoryStream()
  
  Dim cs As CryptoStream = _
  
  New CryptoStream(ms, cryptoProvider.CreateEncryptor(KEY_192, IV_192), _
  
  CryptoStreamMode.Write)
  
  Dim sw As StreamWriter = New StreamWriter(cs)
  
  
  sw.Write(value)
  
  sw.Flush()
  
  cs.FlushFinalBlock()
  
  ms.Flush()
  
  
  '再转换为一个字符串
  
  Return Convert.ToBase64String(ms.GetBuffer(), 0, ms.Length)
  
  End If
  
  End Function
  
  
  
  'TRIPLE DES解密
  
  Public Shared Function DecryptTripleDES(ByVal value As String) As String
  
  If value <> "" Then
  
  Dim cryptoProvider As TripleDESCryptoServiceProvider = _
  
  New TripleDESCryptoServiceProvider()
  
  
  '从字符串转换为字节组
  
  Dim buffer As Byte() = Convert.FromBase64String(value)
  
  Dim ms As MemoryStream = New MemoryStream(buffer)
  
  Dim cs As CryptoStream = _
  
  New CryptoStream(ms, cryptoProvider.CreateDecryptor(KEY_192, IV_192), _
  
  CryptoStreamMode.Read)
  
  Dim sr As StreamReader = New StreamReader(cs)
  
  
  Return sr.ReadToEnd()
  
  End If
  
  End Function
  
  
  End Class
  
  上面我们将一组字节初始化为密钥，并且使用的是数字常量，如果你在实际应用中也这样做，这些字节一定要在0和255之间，这是一个字节允许的范围值。
  
  三、创建一个Cookie的应用类
  
  下面我们就创建一个简单的类，来设置和获取Cookies。
  
  Public Class CookieUtil
  
  
  '设置COOKIE *****************************************************
  
  
  'SetTripleDESEncryptedCookie （只针对密钥和Cookie数据）
  
  Public Shared Sub SetTripleDESEncryptedCookie(ByVal key As String, _
  
  ByVal value As String)
  
  key = CryptoUtil.EncryptTripleDES(key)
  
  value = CryptoUtil.EncryptTripleDES(value)
  
  
  SetCookie(key, value)
  
  End Sub
  
  
  'SetTripleDESEncryptedCookie （增加了Cookie数据的有效期参数）
  
  Public Shared Sub SetTripleDESEncryptedCookie(ByVal key As String, _
  
  ByVal value As String, ByVal expires As Date)
  
  key = CryptoUtil.EncryptTripleDES(key)
  
  value = CryptoUtil.EncryptTripleDES(value)
  
  
  SetCookie(key, value, expires)
  
  End Sub
  
  
  
  'SetEncryptedCookie（只针对密钥和Cookie数据）
  
  Public Shared Sub SetEncryptedCookie(ByVal key As String, _
  
  ByVal value As String)
  
  key = CryptoUtil.Encrypt(key)
  
  value = CryptoUtil.Encrypt(value)
  
  
  SetCookie(key, value)
  
  End Sub
  
  
  'SetEncryptedCookie （增加了Cookie数据的有效期参数）
  
  Public Shared Sub SetEncryptedCookie(ByVal key As String, _
  
  ByVal value As String, ByVal expires As Date)
  
  key = CryptoUtil.Encrypt(key)
  
  value = CryptoUtil.Encrypt(value)
  
  
  SetCookie(key, value, expires)
  
  End Sub
  
  
  
  'SetCookie （只针对密钥和Cookie数据）
  
  Public Shared Sub SetCookie(ByVal key As String, ByVal value As String)
  
  '编码部分
  
  key = HttpContext.Current.Server.UrlEncode(key)
  
  value = HttpContext.Current.Server.UrlEncode(value)
  
  
  Dim cookie As HttpCookie
  
  cookie = New HttpCookie(key, value)
  
  SetCookie(cookie)
  
  End Sub
  
  
  'SetCookie（增加了Cookie数据的有效期参数）
  
  Public Shared Sub SetCookie(ByVal key As String, _
  
  ByVal value As String, ByVal expires As Date)
  
  '编码部分
  
  key = HttpContext.Current.Server.UrlEncode(key)
  
  value = HttpContext.Current.Server.UrlEncode(value)
  
  
  Dim cookie As HttpCookie
  
  cookie = New HttpCookie(key, value)
  
  cookie.Expires = expires
  
  SetCookie(cookie)
  
  End Sub
  
  
  'SetCookie （只针对HttpCookie）
  
  Public Shared Sub SetCookie(ByVal cookie As HttpCookie)
  
  HttpContext.Current.Response.Cookies.Set(cookie)
  
  End Sub
  
  
  '获取COOKIE *****************************************************
  
  
  Public Shared Function GetTripleDESEncryptedCookieValue(ByVal key As String) _
  
  As String
  
  '只对密钥加密
  
  key = CryptoUtil.EncryptTripleDES(key)
  
  
  '获取Cookie值
  
  Dim value As String
  
  value = GetCookieValue(key)
  
  '解密Cookie值
  
  value = CryptoUtil.DecryptTripleDES(value)
  
  Return value
  
  End Function
  
  
  Public Shared Function GetEncryptedCookieValue(ByVal key As String) As String
  
  '只对密钥加密
  
  key = CryptoUtil.Encrypt(key)
  
  
  '获取Cookie值
  
  Dim value As String
  
  value = GetCookieValue(key)
  
  '解密Cookie值
  
  value = CryptoUtil.Decrypt(value)
  
  Return value
  
  End Function
  
  
  Public Shared Function GetCookie(ByVal key As String) As HttpCookie
  
  '编码密钥
  
  key = HttpContext.Current.Server.UrlEncode(key)
  
  Return HttpContext.Current.Request.Cookies.Get(key)
  
  End Function
  
  
  Public Shared Function GetCookieValue(ByVal key As String) As String
  
  Try
  
  '编码在GetCookie里完成
  
  '获取Cookie值
  
  Dim value As String
  
  value = GetCookie(key).Value
  
  '解码所存储的值
  
  value = HttpContext.Current.Server.UrlDecode(value)
  
  Return value
  
  Catch
  
  End Try
  
  End Function
  
  
  End Class
  
  上面的设置功能中，有些功能附加提供了Cookie有效期这个参数。不设置该参数，Cookie将只为浏览器会话才保存在内存中。为了设置永久的Cookie，就需要设置有效期参数。
  
  上面我们对密钥和Cookies值进行了编码与解码，其原因是Cookies与URLs有同样的限制，字符“=”和“；”是保留的，不能使用。这在保存加密后的数据时尤其重要，因为加密算法将添加“=”，按所分配块的大小来填满该数据块。
  
  好了，你会保护Cookies数据了吧？
    做人要厚道，请注明转自chinazhan中国站长(www.ChinaZhan.com)。