Google Authenticator(谷歌身份验证器)C#版

沫欢發表於 2019-6-19 22:58:00

Google Authenticator(谷歌身份验证器)C#版

<div>摘要：Google Authenticator(谷歌身份验证器)，是谷歌公司推出的一款动态令牌工具，解决账户使用时遭到的一些不安全的操作进行的“二次验证”，认证器基于RFC文档中的HOTP/TOTP算法实现，是一种从共享秘钥和时间或次数一次性令牌的算法。在工作中可以通过认证器方式对账户有更好的保护，但是在查阅一些资料发现适合我这样的小白文章真的很少，针对于C#的文章就更加少了，本文主要是对C#如何使用Google Authenticator(谷歌身份验证器)进行探讨，有不足之处还请见谅。</div>
<h2>Google Authenticator(谷歌身份验证器)</h2>
<h3>什么是认证器？怎么对接？</h3>
<div>
Google Authenticator(谷歌身份验证器)是微软推出的一个动态密令工具，它有两种密令模式。分别是“TOTP 基于时间”、“HOTP 基于计数器”，通过手机上简单的设置就可以设定自己独一的动态密令，那么我们怎么将我们的程序和认证器进行对接呢？其实谷歌认证器并不是需要我们对接这个工具的API而是通过算法来决定，谷歌使用使用HMAC算法生成密令，通过基于次数或者基于时间两个模板进行计算，因此在程序中只需要使用相同的算法即可与之匹配。
</div>
<div>
<h4>TOTP 基于时间</h4>
<ul>
<li>HMAC算法使用固定为HmacSHA1</li>
<li>更新时长固定为30秒</li>
<li>APP端输入数据维度只有两个：账户名称（自己随意填写方便自己查看）和base32格式的key</li>
</ul>
</div>
<div>
<h4>HOTP 基于计数器</h4>
基于计数器模式是根据一个共享秘钥K和一个C计数器进行算法计算
</div>
<h3>认证器安装</h3>
<div>
手机需要安装认证器：
<ul>
<li>Android版：安卓版下载</li>
<li>IOS版：苹果版下载</li>
</ul>
</div>
<h3>效果图</h3>
<h3><img src="https://img2018.cnblogs.com/blog/1407129/201906/1407129-20190619224446456-757566347.gif" alt="" width="335" height="175"><img src="https://img2018.cnblogs.com/blog/1407129/201906/1407129-20190619224616709-1845395391.gif" alt="">容</h3>
<h3>案例</h3>
<h3>控制台</h3>
<div>
<div class="cnblogs_code"><img id="code_img_closed_055caeba-c22e-44bf-bf70-51c2bd4c2a79" class="code_img_closed" src="https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif" alt=""><img id="code_img_opened_055caeba-c22e-44bf-bf70-51c2bd4c2a79" class="code_img_opened" style="display: none" src="https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif" alt="">
<div id="cnblogs_code_open_055caeba-c22e-44bf-bf70-51c2bd4c2a79" class="cnblogs_code_hide">
<pre> 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5
 6 namespace GoogleAuthenticator
 7 {
 8 class Program
 9 {
10 static void Main(string[] args)
11 {
12 long duration = 30;
13 string key = "xeon997@foxmail.com";
14 GoogleAuthenticator authenticator = new GoogleAuthenticator(duration, key);
15 var mobileKey = authenticator.GetMobilePhoneKey();
16
17 while (true)
18 {
19
20 Console.WriteLine("手机端秘钥为：" + mobileKey);
21
22 var code = authenticator.GenerateCode();
23 Console.WriteLine("动态验证码为：" + code);
24
25 Console.WriteLine("刷新倒计时：" + authenticator.EXPIRE_SECONDS);
26
27 System.Threading.Thread.Sleep(1000);
28 Console.Clear();
29 }
30 }
31 }
32 }</pre>
</div>
View Code</div>
 
</div>
<h3>认证器类</h3>
<div>
<div class="cnblogs_code"><img id="code_img_closed_53732977-0088-4141-97be-dd6488d5880b" class="code_img_closed" src="https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif" alt=""><img id="code_img_opened_53732977-0088-4141-97be-dd6488d5880b" class="code_img_opened" style="display: none" src="https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif" alt="">
<div id="cnblogs_code_open_53732977-0088-4141-97be-dd6488d5880b" class="cnblogs_code_hide">
<pre>1 using GoogleAuthorization;
2 using System;
3 using System.Security.Cryptography;
4 using System.Text;
5 namespace GoogleAuthenticator
6 {
7 public class GoogleAuthenticator
8 {
9 /// <summary>
 10 /// 初始化验证码生成规则
 11 /// </summary>
 12 /// <param name="key">秘钥(手机使用Base32码)</param>
 13 /// <param name="duration">验证码间隔多久刷新一次（默认30秒和google同步）</param>
 14 public GoogleAuthenticator(long duration = 30, string key = "xeon997@foxmail.com")
 15 {
 16 this.SERECT_KEY = key;
 17 this.SERECT_KEY_MOBILE = Base32.ToString(Encoding.UTF8.GetBytes(key));
 18 this.DURATION_TIME = duration;
 19 }
 20
 21 /// <summary>
 22 /// 间隔时间
 23 /// </summary>
 24 private long DURATION_TIME { get; set; }
 25
 26 /// <summary>
 27 /// 迭代次数
 28 /// </summary>
 29 private long COUNTER
 30 {
 31 get
 32 {
 33 return (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalSeconds / DURATION_TIME;
 34 }
 35 }
 36
 37 /// <summary>
 38 /// 秘钥
 39 /// </summary>
 40 private string SERECT_KEY { get; set; }
 41
 42 /// <summary>
 43 /// 手机端输入的秘钥
 44 /// </summary>
 45 private string SERECT_KEY_MOBILE { get; set; }
 46
 47 /// <summary>
 48 /// 到期秒数
 49 /// </summary>
 50 public long EXPIRE_SECONDS
 51 {
 52 get
 53 {
 54 return (DURATION_TIME - (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalSeconds % DURATION_TIME);
 55 }
 56 }
 57
 58 /// <summary>
 59 /// 获取手机端秘钥
 60 /// </summary>
 61 /// <returns></returns>
 62 public string GetMobilePhoneKey()
 63 {
 64 if (SERECT_KEY_MOBILE == null)
 65 throw new ArgumentNullException("SERECT_KEY_MOBILE");
 66 return SERECT_KEY_MOBILE;
 67 }
 68
 69 /// <summary>
 70 /// 生成认证码
 71 /// </summary>
 72 /// <returns>返回验证码</returns>
 73 public string GenerateCode()
 74 {
 75 return GenerateHashedCode(SERECT_KEY, COUNTER);
 76 }
 77
 78 /// <summary>
 79 /// 按照次数生成哈希编码
 80 /// </summary>
 81 /// <param name="secret">秘钥</param>
 82 /// <param name="iterationNumber">迭代次数</param>
 83 /// <param name="digits">生成位数</param>
 84 /// <returns>返回验证码</returns>
 85 private string GenerateHashedCode(string secret, long iterationNumber, int digits = 6)
 86 {
 87 byte[] counter = BitConverter.GetBytes(iterationNumber);
 88
 89 if (BitConverter.IsLittleEndian)
 90 Array.Reverse(counter);
 91
 92 byte[] key = Encoding.ASCII.GetBytes(secret);
 93
 94 HMACSHA1 hmac = new HMACSHA1(key, true);
 95
 96 byte[] hash = hmac.ComputeHash(counter);
 97
 98 int offset = hash & 0xf;
 99
100 int binary =
101 ((hash & 0x7f) << 24)
102 | ((hash & 0xff) << 16)
103 | ((hash & 0xff) << 8)
104 | (hash & 0xff);
105
106 int password = binary % (int)Math.Pow(10, digits); // 6 digits
107
108 return password.ToString(new string('0', digits));
109 }
110 }
111 }</pre>
</div>
View Code</div>
 
Base32转码类
</div>
<div>
<div class="cnblogs_code"><img id="code_img_closed_333f57cc-4312-4d81-b388-a2b62a46b77a" class="code_img_closed" src="https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif" alt=""><img id="code_img_opened_333f57cc-4312-4d81-b388-a2b62a46b77a" class="code_img_opened" style="display: none" src="https://images.cnblogs.com/OutliningIndicators/ExpandedBlockStart.gif" alt="">
<div id="cnblogs_code_open_333f57cc-4312-4d81-b388-a2b62a46b77a" class="cnblogs_code_hide">
<pre>1 using System;
2 namespace GoogleAuthorization
3 {
4 public static class Base32
5 {
6 public static byte[] ToBytes(string input)
7 {
8 if (string.IsNullOrEmpty(input))
9 {
 10 throw new ArgumentNullException("input");
 11 }
 12
 13 input = input.TrimEnd('=');
 14 int byteCount = input.Length * 5 / 8;
 15 byte[] returnArray = new byte;
 16
 17 byte curByte = 0, bitsRemaining = 8;
 18 int mask = 0, arrayIndex = 0;
 19
 20 foreach (char c in input)
 21 {
 22 int cValue = CharToValue(c);
 23
 24 if (bitsRemaining > 5)
 25 {
 26 mask = cValue << (bitsRemaining - 5);
 27 curByte = (byte)(curByte | mask);
 28 bitsRemaining -= 5;
 29 }
 30 else
 31 {
 32 mask = cValue >> (5 - bitsRemaining);
 33 curByte = (byte)(curByte | mask);
 34 returnArray = curByte;
 35 curByte = (byte)(cValue << (3 + bitsRemaining));
 36 bitsRemaining += 3;
 37 }
 38 }
 39
 40 if (arrayIndex != byteCount)
 41 {
 42 returnArray = curByte;
 43 }
 44
 45 return returnArray;
 46 }
 47
 48 public static string ToString(byte[] input)
 49 {
 50 if (input == null || input.Length == 0)
 51 {
 52 throw new ArgumentNullException("input");
 53 }
 54
 55 int charCount = (int)Math.Ceiling(input.Length / 5d) * 8;
 56 char[] returnArray = new char;
 57
 58 byte nextChar = 0, bitsRemaining = 5;
 59 int arrayIndex = 0;
 60
 61 foreach (byte b in input)
 62 {
 63 nextChar = (byte)(nextChar | (b >> (8 - bitsRemaining)));
 64 returnArray = ValueToChar(nextChar);
 65
 66 if (bitsRemaining < 4)
 67 {
 68 nextChar = (byte)((b >> (3 - bitsRemaining)) & 31);
 69 returnArray = ValueToChar(nextChar);
 70 bitsRemaining += 5;
 71 }
 72
 73 bitsRemaining -= 3;
 74 nextChar = (byte)((b << bitsRemaining) & 31);
 75 }
 76
 77 if (arrayIndex != charCount)
 78 {
 79 returnArray = ValueToChar(nextChar);
 80 while (arrayIndex != charCount) returnArray = '=';
 81 }
 82
 83 return new string(returnArray);
 84 }
 85
 86 private static int CharToValue(char c)
 87 {
 88 var value = (int)c;
 89
 90 if (value < 91 && value > 64)
 91 {
 92 return value - 65;
 93 }
 94 if (value < 56 && value > 49)
 95 {
 96 return value - 24;
 97 }
 98 if (value < 123 && value > 96)
 99 {
100 return value - 97;
101 }
102
103 throw new ArgumentException("Character is not a Base32 character.", "c");
104 }
105
106 private static char ValueToChar(byte b)
107 {
108 if (b < 26)
109 {
110 return (char)(b + 65);
111 }
112
113 if (b < 32)
114 {
115 return (char)(b + 24);
116 }
117
118 throw new ArgumentException("Byte is not a value Base32 value.", "b");
119 }
120 }
121 }</pre>
</div>
View Code</div>
 
</div>
<h2>总结</h2>
<h3>需要注意的坑</h3>
<div>
移动端下载的认证器的秘钥key是通过base32转码得到的，而程序端是直接输入源码。
如原秘钥为xeon997@foxmail.com生成的base32码PBSW63RZHE3UAZTPPBWWC2LMFZRW63I=才是移动端需要输入的秘钥。
在网上找了很多资料没有发现关于C#的案例，所以在此记录一下自己遇到的坑，让更多的人能够跳过这个坑。
案例地址：
git:https://github.com/CN-Yi/GoogleAuthenticator
gitee:https://gitee.com/hsyi/GoogleAuthenticator
在此感谢提供学习资料的大神们，如果有错误的地方欢迎留言。
<div> </div>
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来源：https://www.cnblogs.com/hsyi/p/11054869.html

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Google Authenticator(谷歌身份验证器)C#版