登陆时候的安全码

注意：只是一个演示思想的代码，代码很乱

default.aspx

 <form id="form1" runat="server">
    <div runat="server" id="div1"> 
        <asp:HiddenField ID="HiddenField1" runat="server" />
        <asp:TextBox ID="TextBox1" runat="server" TextMode="Password"></asp:TextBox><br />
    <table>
    <tr>
        <td width="40px">
            <input type="button" ID="Button1" runat="server" style="30px"/></td><td width="40px">
                &nbsp;<input type="button" ID="Button2" runat="server"  style="30px"/></td><td width="40px">
                &nbsp;<input type="button" ID="Button3" runat="server" style="30px"/></td>
    </tr>
      <tr>
        <td width="40px"><input type="button" ID="Button4" runat="server" style="30px"/></td><td width="40px">
            &nbsp;<input type="button" ID="Button5" runat="server" style="30px"/></td><td width="40px">
            &nbsp;<input type="button" ID="Button6" runat="server" style="30px"/></td>
    </tr>
      <tr>
        <td width="40px"><input type="button" ID="Button7" runat="server" style="30px"/></td><td width="40px">
            &nbsp;<input type="button" ID="Button8" runat="server" style="30px"/></td><td width="40px">
            &nbsp;<input type="button" ID="Button9" runat="server" style="30px"/></td>
    </tr>
      <tr>
        <td width="40px"><input type="button" ID="Button10" runat="server" style="30px"/></td><td width="80px" colspan="2"><input type="button" value="重新输入" onclick="location.href=location.href" /></td>
    </tr>
    </table>
    <asp:Button ID="Button12" runat="server" Text="确认" OnClick="Button12_Click" Width="127px" />
    </div>
        
    </form>

default.aspx.cs

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page
{
    private Random rnd = new Random();

    private string GetOneRandomNum()
    {
        string strtemp;
        int itmp = rnd.Next(36);
        if (itmp < 10)
            strtemp = rnd.Next(10).ToString();
        else
            strtemp = Convert.ToChar(rnd.Next(26) + 'A').ToString();
        return strtemp;
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            
            Session["SecurityCode"] = "";
            System.Collections.Generic.Dictionary<string, string> pswList = new System.Collections.Generic.Dictionary<string, string>();
            string psw = Request.QueryString["psw"];
            int strength = 10;

            // 位置初始化
            int left = 50 + rnd.Next(150);
            int top = 50 + rnd.Next(150);
            div1.Attributes.Add("style", "left:" + left + "px; top:" + top + "px; position:absolute;");
            

            // 初始化密码的对应随机数
            for (int i = 0; i < psw.Length; i++)
            {
                string tmp = "";
                for (int j = 0; j < strength; j++)
                {
                    tmp += GetOneRandomNum();
                }
                if (!pswList.ContainsKey(psw[i].ToString())) pswList.Add(psw[i].ToString(), tmp);
            }

            //安全码
            for (int i = 0; i < psw.Length; i++)
            {
                Session["SecurityCode"] += pswList[psw[i].ToString()];
            }

            //为按钮随机排列并且分配安全码
            System.Collections.Generic.List<int> list = new System.Collections.Generic.List<int>();
            for (int i = 0; i <= 9; i++)
                list.Add(i);
            for (int i = 1; i <= 10; i++)
            {
                int num = list[rnd.Next(list.Count)];
                list.Remove(num);
                HtmlInputButton btn = Page.FindControl("Button" + i) as HtmlInputButton;
                if (btn != null)
                {
                    btn.Value = num.ToString();
                    if (pswList.ContainsKey(num.ToString()))
                        btn.Attributes.Add("onclick", "document.getElementById('HiddenField1').value+='" + pswList[num.ToString()] + "';document.getElementById('TextBox1').value+='1';");
                    else
                    {
                        string tmp = "";
                        for (int k = 0; k < strength; k++)
                        {
                            tmp += GetOneRandomNum();
                        }
                        btn.Attributes.Add("onclick", "document.getElementById('HiddenField1').value+='" + tmp + "';document.getElementById('TextBox1').value+='1';");
                    }
                }
            }       
   
        }
    }
 

    protected void Button12_Click(object sender, EventArgs e)
    {
        if (HiddenField1.Value != null && Session["SecurityCode"] != null)
        {
            if (HiddenField1.Value == Session["SecurityCode"].ToString())
            {
                Response.Write("<script>alert('正确');window.top.location.href='ok.aspx';</script>");
            }
            else
            {
                Response.Write("<script>alert('错误');location.href=location.href;</script>");
            }
        }
    }
}