MVC使用极验验证制作登录验证码

       在之前的项目中，如果有需要使用验证码，基本都是自己用GDI+画图出来，简单好用，但是却也存在了一些小问题，首先若较少干扰线，则安全性不是很高，验证码容易被机器识别，若多画太多干扰线条，机器人识别率下降的同时，人眼的识别率也同步下降（震惊哭）。更为重要的是，GDI+绘制的验证码一般来说也不会很美观，如果做一个炫酷的登陆界面却配了这样一个验证码，画风诡异，丑到极致。

      再后来浏览网页的过程中，发现很多很多网站项目中都使用了一种叫极验验证的验证码，采用移动滑块的方式进行验证，方便美观。而一番搜索之后了解到，官方提供的免费版也足以应付我手头的大多数项目了，不禁想把在MVC学习过程中试着使用极验验证来作为登录的验证码。

      极验官方提供了C#的SDK和Demo供开发者参考，不过是Webform版本的，可读性不是很高，而现在使用Webform进行网站开发的也基本消失了，我将在官方Webform代码的基础上，将其用在ASP.NET MVC程序中。

注册极验

到极验官网注册账号之后进入后台管理界面，点击添加验证

添加后我们可以得到ID和KEY

完成验证逻辑

1. 首先我们需要引入官方的Geetestlib类

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.Net;
using System.IO;
 
namespace PMS.WebApp.Models
{
 /// <summary>
 /// GeetestLib 极验验证C# SDK基本库
 /// </summary>
 public class GeetestLib
 {
  /// <summary>
  /// SDK版本号
  /// </summary>
  public const String version = "3.2.0";
  /// <summary>
  /// SDK开发语言
  /// </summary>
  public const String sdkLang = "csharp";
  /// <summary>
  /// 极验验证API URL
  /// </summary>
  protected const String apiUrl = "http://api.geetest.com";
  /// <summary>
  /// register url
  /// </summary>
  protected const String registerUrl = "/register.php";
  /// <summary>
  /// validate url
  /// </summary>
  protected const String validateUrl = "/validate.php";
  /// <summary>
  /// 极验验证API服务状态Session Key
  /// </summary>
  public const String gtServerStatusSessionKey = "gt_server_status";
  /// <summary>
  /// 极验验证二次验证表单数据 Chllenge
  /// </summary>
  public const String fnGeetestChallenge = "geetest_challenge";
  /// <summary>
  /// 极验验证二次验证表单数据 Validate
  /// </summary>
  public const String fnGeetestValidate = "geetest_validate";
  /// <summary>
  /// 极验验证二次验证表单数据 Seccode
  /// </summary>
  public const String fnGeetestSeccode = "geetest_seccode";
  private String userID = "";
  private String responseStr = "";
  private String captchaID = "";
  private String privateKey = "";
 
  /// <summary>
  /// 验证成功结果字符串
  /// </summary>
  public const int successResult = 1;
  /// <summary>
  /// 证结失败验果字符串
  /// </summary>
  public const int failResult = 0;
  /// <summary>
  /// 判定为机器人结果字符串
  /// </summary>
  public const String forbiddenResult = "forbidden";
 
  /// <summary>
  /// GeetestLib构造函数
  /// </summary>
  /// <param name="publicKey">极验验证公钥</param>
  /// <param name="privateKey">极验验证私钥</param>
  public GeetestLib(String publicKey, String privateKey)
  {
   this.privateKey = privateKey;
   this.captchaID = publicKey;
  }
  private int getRandomNum()
  {
   Random rand =new Random();
   int randRes = rand.Next(100);
   return randRes;
  }
 
  /// <summary>
  /// 验证初始化预处理
  /// </summary>
  /// <returns>初始化结果</returns>
  public Byte preProcess()
  {
   if (this.captchaID == null)
   {
    Console.WriteLine("publicKey is null!");
   }
   else
   {
    String challenge = this.registerChallenge();
    if (challenge.Length == 32)
    {
     this.getSuccessPreProcessRes(challenge);
     return 1;
    }
    else
    {
     this.getFailPreProcessRes();
     Console.WriteLine("Server regist challenge failed!");
    }
   }
 
   return 0;
 
  }
  public Byte preProcess(String userID)
  {
   if (this.captchaID == null)
   {
    Console.WriteLine("publicKey is null!");
   }
   else
   {
    this.userID = userID;
    String challenge = this.registerChallenge();
    if (challenge.Length == 32)
    {
     this.getSuccessPreProcessRes(challenge);
     return 1;
    }
    else
    {
     this.getFailPreProcessRes();
     Console.WriteLine("Server regist challenge failed!");
    }
   }
 
   return 0;
 
  }
  public String getResponseStr()
  {
   return this.responseStr;
  }
  /// <summary>
  /// 预处理失败后的返回格式串
  /// </summary>
  private void getFailPreProcessRes()
  {
   int rand1 = this.getRandomNum();
   int rand2 = this.getRandomNum();
   String md5Str1 = this.md5Encode(rand1 + "");
   String md5Str2 = this.md5Encode(rand2 + "");
   String challenge = md5Str1 + md5Str2.Substring(0, 2);
   this.responseStr = "{" + string.Format(
     "\"success\":{0},\"gt\":\"{1}\",\"challenge\":\"{2}\"", 0,
    this.captchaID, challenge) + "}";
  }
  /// <summary>
  /// 预处理成功后的标准串
  /// </summary>
  private void getSuccessPreProcessRes(String challenge)
  {
   challenge = this.md5Encode(challenge + this.privateKey);
   this.responseStr ="{" + string.Format(
    "\"success\":{0},\"gt\":\"{1}\",\"challenge\":\"{2}\"", 1, 
    this.captchaID, challenge) + "}";
  }
  /// <summary>
  /// failback模式的验证方式
  /// </summary>
  /// <param name="challenge">failback模式下用于与validate一起解码答案， 判断验证是否正确</param>
  /// <param name="validate">failback模式下用于与challenge一起解码答案， 判断验证是否正确</param>
  /// <param name="seccode">failback模式下，其实是个没用的参数</param>
  /// <returns>验证结果</returns>
  public int failbackValidateRequest(String challenge, String validate, String seccode)
  {
   if (!this.requestIsLegal(challenge, validate, seccode)) return GeetestLib.failResult;
   String[] validateStr = validate.Split(&#39;_&#39;);
   String encodeAns = validateStr[0];
   String encodeFullBgImgIndex = validateStr[1];
   String encodeImgGrpIndex = validateStr[2];
   int decodeAns = this.decodeResponse(challenge, encodeAns);
   int decodeFullBgImgIndex = this.decodeResponse(challenge, encodeFullBgImgIndex);
   int decodeImgGrpIndex = this.decodeResponse(challenge, encodeImgGrpIndex);
   int validateResult = this.validateFailImage(decodeAns, decodeFullBgImgIndex, decodeImgGrpIndex);
   return validateResult;
  }
  private int validateFailImage(int ans, int full_bg_index, int img_grp_index)
  {
   const int thread = 3;
   String full_bg_name = this.md5Encode(full_bg_index + "").Substring(0, 10);
   String bg_name = md5Encode(img_grp_index + "").Substring(10, 10);
   String answer_decode = "";
   for (int i = 0;i < 9; i++)
   {
    if (i % 2 == 0) answer_decode += full_bg_name.ElementAt(i);
    else if (i % 2 == 1) answer_decode += bg_name.ElementAt(i);
   }
   String x_decode = answer_decode.Substring(4);
   int x_int = Convert.ToInt32(x_decode, 16);
   int result = x_int % 200;
   if (result < 40) result = 40;
   if (Math.Abs(ans - result) < thread) return GeetestLib.successResult;
   else return GeetestLib.failResult;
  }
  private Boolean requestIsLegal(String challenge, String validate, String seccode)
  {
   if (challenge.Equals(string.Empty) || validate.Equals(string.Empty) || seccode.Equals(string.Empty)) return false;
   return true;
  }
 
  /// <summary>
  /// 向gt-server进行二次验证
  /// </summary>
  /// <param name="challenge">本次验证会话的唯一标识</param>
  /// <param name="validate">拖动完成后server端返回的验证结果标识字符串</param>
  /// <param name="seccode">验证结果的校验码，如果gt-server返回的不与这个值相等则表明验证失败</param>
  /// <returns>二次验证结果</returns>
  public int enhencedValidateRequest(String challenge, String validate, String seccode)
  {
   if (!this.requestIsLegal(challenge, validate, seccode)) return GeetestLib.failResult;
   if (validate.Length > 0 && checkResultByPrivate(challenge, validate))
   {
    String query = "seccode=" + seccode + "&sdk=csharp_" + GeetestLib.version;
    String response = "";
    try
    {
     response = postValidate(query);
    }
    catch (Exception e)
    {
     Console.WriteLine(e);
    }
    if (response.Equals(md5Encode(seccode)))
    {
     return GeetestLib.successResult;
    }
   }
   return GeetestLib.failResult;
  }
  public int enhencedValidateRequest(String challenge, String validate, String seccode, String userID)
  {
   if (!this.requestIsLegal(challenge, validate, seccode)) return GeetestLib.failResult;
   if (validate.Length > 0 && checkResultByPrivate(challenge, validate))
   {
    String query = "seccode=" + seccode + "&user_id=" + userID + "&sdk=csharp_" + GeetestLib.version;
    String response = "";
    try
    {
     response = postValidate(query);
    }
    catch (Exception e)
    {
     Console.WriteLine(e);
    }
    if (response.Equals(md5Encode(seccode)))
    {
     return GeetestLib.successResult;
    }
   }
   return GeetestLib.failResult;
  }
  private String readContentFromGet(String url)
  {
   try
   {
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
    request.Timeout = 20000;
    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
    Stream myResponseStream = response.GetResponseStream();
    StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));
    String retString = myStreamReader.ReadToEnd();
    myStreamReader.Close();
    myResponseStream.Close();
    return retString;
   }
   catch
   {
    return "";  
   }
 
  }
  private String registerChallenge()
  {
   String url = "";
   if (string.Empty.Equals(this.userID))
   {
    url = string.Format("{0}{1}?gt={2}", GeetestLib.apiUrl, GeetestLib.registerUrl, this.captchaID);
   }
   else
   {
    url = string.Format("{0}{1}?gt={2}&user_id={3}", GeetestLib.apiUrl, GeetestLib.registerUrl, this.captchaID, this.userID);
   }
   string retString = this.readContentFromGet(url);
   return retString;
  }
  private Boolean checkResultByPrivate(String origin, String validate)
  {
   String encodeStr = md5Encode(privateKey + "geetest" + origin);
   return validate.Equals(encodeStr);
  }
  private String postValidate(String data)
  {
   String url = string.Format("{0}{1}", GeetestLib.apiUrl, GeetestLib.validateUrl);
   HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
   request.Method = "POST";
   request.ContentType = "application/x-www-form-urlencoded";
   request.ContentLength = Encoding.UTF8.GetByteCount(data);
   // 发送数据
   Stream myRequestStream = request.GetRequestStream();
   byte[] requestBytes = System.Text.Encoding.ASCII.GetBytes(data);
   myRequestStream.Write(requestBytes, 0, requestBytes.Length);
   myRequestStream.Close();
 
   HttpWebResponse response = (HttpWebResponse)request.GetResponse();
   // 读取返回信息
   Stream myResponseStream = response.GetResponseStream();
   StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));
   string retString = myStreamReader.ReadToEnd();
   myStreamReader.Close();
   myResponseStream.Close();
 
   return retString;
 
  }
  private int decodeRandBase(String challenge)
  {
   String baseStr = challenge.Substring(32, 2);
   List<int> tempList = new List<int>();
   for(int i = 0; i < baseStr.Length; i++)
   {
    int tempAscii = (int)baseStr[i];
    tempList.Add((tempAscii > 57) ? (tempAscii - 87)
     : (tempAscii - 48));
   }
   int result = tempList.ElementAt(0) * 36 + tempList.ElementAt(1);
   return result;
  }
  private int decodeResponse(String challenge, String str)
  {
   if (str.Length>100) return 0;
   int[] shuzi = new int[] { 1, 2, 5, 10, 50};
   String chongfu = "";
   Hashtable key = new Hashtable();
   int count = 0;
   for (int i=0;i<challenge.Length;i++)
   {
    String item = challenge.ElementAt(i) + "";
    if (chongfu.Contains(item)) continue;
    else
    {
     int value = shuzi[count % 5];
     chongfu += item;
     count++;
     key.Add(item, value);
    }
   }
   int res = 0;
   for (int i = 0; i < str.Length; i++) res += (int)key[str[i]+""];
   res = res - this.decodeRandBase(challenge);
   return res;
  }
  private String md5Encode(String plainText)
  {
   MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
   string t2 = BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(plainText)));
   t2 = t2.Replace("-", "");
   t2 = t2.ToLower();
   return t2;
  }
 
 }
}

2. 获取验证码

引入Jquery库

添加用于放置验证码的div（需要放到form表单中）

添加JS代码用于获取验证码

<script>
 window.addEventListener(&#39;load&#39;, processGeeTest);
 
 function processGeeTest() {
  $.ajax({
   // 获取id，challenge，success（是否启用failback）
   url: "/Login/GeekTest",
   type: "get",
   dataType: "json", // 使用jsonp格式
   success: function (data) {
    // 使用initGeetest接口
    // 参数1：配置参数，与创建Geetest实例时接受的参数一致
    // 参数2：回调，回调的第一个参数验证码对象，之后可以使用它做appendTo之类的事件
    initGeetest({
     gt: data.gt,
     challenge: data.challenge,
     product: "float", // 产品形式
     offline: !data.success
    },
     handler);
   }
  });
 }
 
 var handler = function (captchaObj) {
  // 将验证码加到id为captcha的元素里
  captchaObj.appendTo("#geetest-container");
 
  captchaObj.onSuccess = function (e) {
   console.log(e);
  }
 
 };
</script>

processGeeTest方法中我们异步请求的地址“/Login/GeekTest”就是获取验证码是后台需要执行的方法

public ActionResult GeekTest()
{
 return Content(GetCaptcha(),"application/json");
}
 
private string GetCaptcha()
{
 var geetest = new GeetestLib("3594e0d834df77cedc7351a02b5b06a4", "b961c8081ce88af7e32a3f45d00dff84");
 var gtServerStatus = geetest.preProcess();
 Session[GeetestLib.gtServerStatusSessionKey] = gtServerStatus;
 return geetest.getResponseStr();
}

3. 校验验证码

注意，当提交form表单时，会将三个和极验有关的参数传到后台方法（geetest_challenge、geetest_validate、geetest_seccode），若验证码未验证成功，则参数为空值。

后台验证方法为：

private bool CheckGeeTestResult()
{
 var geetest = new GeetestLib("3594e0d834df77cedc7351a02b5b06a4", "b961c8081ce88af7e32a3f45d00dff84 ");
 var gtServerStatusCode = (byte)Session[GeetestLib.gtServerStatusSessionKey];
 var userId = (string)Session["userID"];
 
 var challenge = Request.Form.Get(GeetestLib.fnGeetestChallenge);
 var validate = Request.Form.Get(GeetestLib.fnGeetestValidate);
 var seccode = Request.Form.Get(GeetestLib.fnGeetestSeccode);
 var result = gtServerStatusCode == 1 ? geetest.enhencedValidateRequest(challenge, validate, seccode, userId) : geetest.failbackValidateRequest(challenge, validate, seccode);
 return result == 1;
}

我们可以在表单中判断验证码是否成功校验：

public ActionResult Login()
{
 if (!CheckGeeTestResult())
  return Content("no:请先完成验证操作。");
 ....
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支PHP中文网。

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