下面的代码实现了一个可逆加密的方法。可以用于对Cookie，QueryString等加密处理。
查看例子
VB.net代码
<%@ Page Language="vb" AutoEventWireup="false" Codebehind="EncString.<a href="http://dev.21tx.com/web/asp/" target="_blank">ASP</a>x.vb"
Inherits="aspx<a href="http://dev.21tx.com/web/" target="_blank">Web</a>.EncString" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<title>一个可逆加密的例子</title>
<meta name="GENERATOR" content="Microsoft Visual Studio.NET 7.0">
<meta name="CODE_LANGUAGE" content="Visual Basic 7.0">
<meta name="vs_defaultClientScript" content="<a href="http://dev.21tx.com/web/javascript/" target="_blank">JavaScript</a>">
<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
</HEAD>
<body MS_POSITIONING="GridLayout">
<asp:Label id="Label1" runat="server"></asp:Label>
<p align="center">
<form id="Form1" method="post" runat="server">
<FONT face="宋体">
<asp:TextBox id="TextBox1" runat="server" Width="96%"></asp:TextBox>
<asp:RadioButtonList id="RadioButtonList1" runat="server" Font-Bold="True"
RepeatDirection="Horizontal" AutoPostBack="True" OnSelectedIndexChanged="ShowRes">
</asp:RadioButtonList>
<asp:TextBox id="TextBox2" runat="server" Width="96%"></asp:TextBox>
</FONT>
</form>
</p>
</body>
</HTML>
后端代码EncString.aspx.vb：
Imports System
Imports System.IO
Imports System.Xml
Imports System.Text
Imports System.Security.Cryptography
Public Class EncString
Inherits System.Web.UI.Page
Protected WithEvents TextBox1 As System.Web.UI.WebControls.TextBox
Protected WithEvents TextBox2 As System.Web.UI.WebControls.TextBox
Protected WithEvents Form1 As System.Web.UI.HtmlControls.HtmlForm
Protected WithEvents Label1 As System.Web.UI.WebControls.Label
Protected WithEvents RadioButtonList1 As System.Web.UI.WebControls.RadioButtonList
#Region " Web Form Designer Generated Code "
'This call is required by the Web Form Designer.
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
End Sub
Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles
MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub
#End Region
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles
MyBase.Load
'Put user code to initialize the page here
Label1.Text = "<h3 align='center'>一个可逆加密的例子</h3>"
If Not IsPostBack Then
Dim MyList As New ArrayList()
MyList.Add("加密")
MyList.Add("解密")
RadioButtonList1.DataSource = MyList
RadioButtonList1.DataBind()
End If
End Sub
' 加密
Public Shared Function EncryptText(ByVal strText As String) As String
Return Encrypt(strText, "&%#@?,:*")
End Function
'解密
Public Shared Function DecryptText(ByVal strText As String) As String
Return Decrypt(strText, "&%#@?,:*")
End Function
'加密函数
Private Shared Function Encrypt(ByVal strText As String, ByVal strEncrKey As String) As String
Dim byKey() As Byte = {}
Dim IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}
Try
byKey = System.Text.Encoding.UTF8.GetBytes(Left(strEncrKey, 8))
Dim des As New DESCryptoServiceProvider()
Dim inputByteArray() As Byte = Encoding.UTF8.GetBytes(strText)
Dim ms As New MemoryStream()
Dim cs As New CryptoStream(ms, des.CreateEncryptor(byKey, IV), CryptoStreamMode.Write)
cs.Write(inputByteArray, 0, inputByteArray.Length)
cs.FlushFinalBlock()
Return Convert.ToBase64String(ms.ToArray())
Catch ex As Exception
Return ex.Message
End Try
End Function
'解密函数
Private Shared Function Decrypt(ByVal strText As String, ByVal sDecrKey As String) As String
Dim byKey() As Byte = {}
Dim IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}
Dim inputByteArray(strText.Length) As Byte
Try
byKey = System.Text.Encoding.UTF8.GetBytes(Left(sDecrKey, 8))
Dim des As New DESCryptoServiceProvider()
inputByteArray = Convert.FromBase64String(strText)
Dim ms As New MemoryStream()
Dim cs As New CryptoStream(ms, des.CreateDecryptor(byKey, IV), CryptoStreamMode.Write)
cs.Write(inputByteArray, 0, inputByteArray.Length)
cs.FlushFinalBlock()
Dim encoding As System.Text.Encoding = System.Text.Encoding.UTF8
Return encoding.GetString(ms.ToArray())
Catch ex As Exception
Return ex.Message
End Try
End Function
Public Sub ShowRes(ByVal sender As Object, ByVal e As System.EventArgs)_
Handles RadioButtonList1.SelectedIndexChanged
If RadioButtonList1.SelectedIndex = 0 Then
TextBox2.Text = EncryptText(TextBox1.Text)
Else
TextBox2.Text = DecryptText(TextBox1.Text)
End If
End Sub
End Class
