这篇文章主要介绍了MVC使用极验验证制作登录验证码学习笔记，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
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 { /// /// GeetestLib 极验验证C# SDK基本库 /// public class GeetestLib { /// /// SDK版本号 /// public const String version = "3.2.0"; /// /// SDK开发语言 /// public const String sdkLang = "csharp"; /// /// 极验验证API URL /// protected const String apiUrl = "http://api.geetest.com"; /// /// register url /// protected const String registerUrl = "/register.php"; /// /// validate url /// protected const String validateUrl = "/validate.php"; /// /// 极验验证API服务状态Session Key /// public const String gtServerStatusSessionKey = "gt_server_status"; /// /// 极验验证二次验证表单数据 Chllenge /// public const String fnGeetestChallenge = "geetest_challenge"; /// /// 极验验证二次验证表单数据 Validate /// public const String fnGeetestValidate = "geetest_validate"; /// /// 极验验证二次验证表单数据 Seccode /// public const String fnGeetestSeccode = "geetest_seccode"; private String userID = ""; private String responseStr = ""; private String captchaID = ""; private String privateKey = ""; /// /// 验证成功结果字符串 /// public const int successResult = 1; /// /// 证结失败验果字符串 /// public const int failResult = 0; /// /// 判定为机器人结果字符串 /// public const String forbiddenResult = "forbidden"; /// /// GeetestLib构造函数 /// /// 极验验证公钥 /// 极验验证私钥 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; } /// /// 验证初始化预处理 /// /// 初始化结果 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; } /// /// 预处理失败后的返回格式串 /// 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) + "}"; } /// /// 预处理成功后的标准串 /// 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) + "}"; } /// /// failback模式的验证方式 /// /// failback模式下用于与validate一起解码答案， 判断验证是否正确 /// failback模式下用于与challenge一起解码答案， 判断验证是否正确 /// failback模式下，其实是个没用的参数 /// 验证结果 public int failbackValidateRequest(String challenge, String validate, String seccode) { if (!this.requestIsLegal(challenge, validate, seccode)) return GeetestLib.failResult; String[] validateStr = validate.Split('_'); 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) /// 向gt-server进行二次验证 /// /// 本次验证会话的唯一标识 /// 拖动完成后server端返回的验证结果标识字符串 /// 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 /// 二次验证结果 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 tempList = new List(); for(int i = 0; i 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 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
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，也希望大家多多支持html中文网。
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