演示执行:概念的三边证明 (中文 (Chinese Simplified))

演示执行:概念的三边证明

Thursday, 20 November 2025

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History JavaScript Security

为了说明这些概念的实际作用,我建立了一个示范项目, 说明这样一个系统如何运作。 仅就教育目的而言,这是微不足道的执行 并故意包括最低程度的保安,以保持编码可读和可理解。

有关演示的危急警告

演示代码有许多安全弱点,不适合现实世界使用。 它旨在展示概念,而不是被部署。

演示项目结构

该演示是一个单独的 ASP.NET Core 9.0 项目,存放在 Mostlylucid.SecureChat.Demo/ 包含以下组成部分:

Mostlylucid.SecureChat.Demo/
├── Controllers/DemoController.cs       # Routes for demo pages
├── Hubs/SecureChatHub.cs              # SignalR for real-time chat
├── Views/
│   ├── Demo/Company.cshtml            # Fake company site (client)
│   └── Demo/Support.cshtml            # Support staff interface
└── wwwroot/js/
    ├── compatibility-shim1.js         # Tiny trigger (1KB)
    └── secure-chat.js                 # Chat application

如何运行演示

  1. 克隆存储库并导航到 Mostlylucid.SecureChat.Demo
  2. 运行运行中 dotnet build && dotnet run
  3. 打开浏览器到 http://localhost:5000/Demo/Company
  4. 添加触发参数 : ?ref=newsletter_2025_jan
  5. 提示时输入编码 : SAFE2025
  6. 在另一个标签页中打开 /Demo/Support 作为支助人员作出反应

微小触发脚本

这是实际代码 compatibility-shim1.js - 注意它多么小和无伤大雅:

(function() {
    'use strict';

    // Actual compatibility checks (makes it look legitimate)
    if (!window.Promise) {
        console.warn('Browser does not support Promises');
    }
    if (!window.fetch) {
        console.warn('Browser does not support Fetch API');
    }

    // Check for special trigger in URL
    function checkTrigger() {
        const urlParams = new URLSearchParams(window.location.search);
        const ref = urlParams.get('ref');

        // Pattern that looks like a marketing tracking parameter
        // e.g., ?ref=newsletter_2025_jan
        if (ref && ref.match(/^newsletter_\d{4}_[a-z]+$/i)) {
            console.log('Loading enhanced support features...');
            loadSecureChat();
            return true;
        }
        return false;
    }

    // Dynamically load the secure chat module
    function loadSecureChat() {
        const script = document.createElement('script');
        script.src = '/js/secure-chat.js';
        script.onload = function() {
            if (window.SecureChat) {
                window.SecureChat.init();
            }
        };
        document.head.appendChild(script);
    }

    // Check on page load
    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', checkTrigger);
    } else {
        checkTrigger();
    }
})();

此脚本仅为 ~ 1KB , 在检查触发程序之前, 做了两件合法的操作( 浏览器兼容性检查) 。 对于检查代码的任何人来说, 它看起来像一个标准的多填工具 。

信号枢纽

后端使用信号R进行实时双向通信。 以下是简化中心结构:

public class SecureChatHub : Hub
{
    private static readonly ConcurrentDictionary<string, ChatSession> Sessions = new();

    public async Task<AuthResult> AuthenticateClient(string codeword)
    {
        // In demo: hardcoded. Production: dynamic, time-limited, rotated
        var validCodeword = "SAFE2025";

        if (codeword == validCodeword)
        {
            var sessionId = Guid.NewGuid().ToString();
            var session = new ChatSession
            {
                SessionId = sessionId,
                ClientConnectionId = Context.ConnectionId,
                StartTime = DateTime.UtcNow,
                IsAuthenticated = true
            };

            Sessions.TryAdd(Context.ConnectionId, session);
            await Groups.AddToGroupAsync(Context.ConnectionId, "authenticated-users");

            // Notify support staff
            await Clients.Group("support-staff")
                .SendAsync("NewSessionAvailable", sessionId, DateTime.UtcNow);

            return new AuthResult { Success = true, SessionId = sessionId };
        }

        return new AuthResult { Success = false };
    }

    public async Task SendMessage(string sessionId, string message)
    {
        if (!Sessions.TryGetValue(Context.ConnectionId, out var session)
            || !session.IsAuthenticated)
        {
            return; // Silently fail
        }

        var chatMessage = new ChatMessage
        {
            SessionId = sessionId,
            Message = message,
            Timestamp = DateTime.UtcNow,
            FromSupport = false
        };

        // Send to support staff in this session
        await Clients.Group($"session-{sessionId}")
            .SendAsync("ReceiveMessage", chatMessage);
    }

    // Additional methods for support staff, session management, etc.
}

客户端聊天

当触发时, 聊天模块创建了一个模式窗口, 其验证倒计时为 30 秒 :

function showAuthPrompt() {
    const chatBody = document.getElementById('chat-body');
    const countdown = { seconds: 30 };

    chatBody.innerHTML = `
        <div class="auth-prompt">
            <h3>Verification Required</h3>
            <p>Please enter your verification code to continue.</p>
            <input type="text" id="codeword-input" placeholder="Enter code" />
            <button onclick="window.SecureChat.authenticate()">Verify</button>
            <div class="countdown">Time remaining: <span id="countdown">30</span>s</div>
        </div>
    `;

    // Countdown timer
    authTimeout = setInterval(() => {
        countdown.seconds--;
        document.getElementById('countdown').textContent = countdown.seconds;
        if (countdown.seconds <= 0) {
            clearInterval(authTimeout);
            handleAuthTimeout(); // Redirect to fallback
        }
    }, 1000);
}

如果认证失败或超时, 系统会重定向为后退 URL( 存储在页面上隐藏的元标记中 ):

function handleAuthFailure() {
    const fallbackMeta = document.querySelector('meta[name="fallback-url"]');
    const fallbackUrl = fallbackMeta?.getAttribute('content')
        ?? 'https://www.example.com/support';

    // Show "service unavailable" briefly
    chatBody.innerHTML = `
        <div class="message system">
            Service temporarily unavailable.<br/>
            Redirecting to standard support...
        </div>
    `;

    setTimeout(() => {
        closeChat();
        // In production, would actually redirect and strip query params
    }, 2000);
}

什么是演示秀

核心概念说明:

  1. 隐藏触发器: URL 参数 ?ref=newsletter_2025_jan 看起来像营销跟踪
  2. 动态装入: 聊天模块仅在触发时负载, 保持初始有效载荷小化
  3. 受时间限制的认证:30秒窗口防止无限期调查
  4. 可显示失败: 失败的认证看起来像一个损坏的支持部件
  5. 实时通信:信号R 启用双向聊天
  6. 分开关注问题:支助工作人员接口是完全分开的

演示不显示的是什么 :

生产系统具有不包含在演示中的更为复杂的特性:

  • 实际加密(在演示文示中以纯文本发送的信息)
  • 编码(可读)
  • 交通布告和时间随机
  • 安全关键交换协议
  • 会话符号旋转
  • 限制率和预防滥用
  • 全面审计全面审计记录
  • 反法证措施
  • 还有其他几十个安全层...

建设系统:腐蚀和消化

成形系统的一个关键方面是使代码难以分析。 演示包括一个简单的构建系统,展示基本的混淆技术。

从来源到部署脚本

以下是转型过程:

flowchart LR
    A[Source Code<br/>compatibility-shim1.src.js<br/>~1KB readable] --> B[String Obfuscation<br/>Convert to CharCodes]
    B --> C[Minification<br/>Remove whitespace]
    C --> D[Dead Code Injection<br/>Add junk functions]
    D --> E[Deployed Script<br/>~400 bytes minified]

    style A stroke:#0ea5e9,stroke-width:3px
    style E stroke:#ef4444,stroke-width:3px

源代码( 可读)

来源是干净和可以理解的:

// Check for trigger pattern
const params = new URLSearchParams(window.location.search);
const ref = params.get('ref');

if (ref && /^newsletter_\d{4}_[a-z]+$/i.test(ref)) {
    // Load the secure chat module
    const script = document.createElement('script');
    script.src = '/js/secure-chat.js';
    document.head.appendChild(script);
}

混乱版本(已部署)

在混乱之后,字符串被分割和编码:

!function(){if(new URLSearchParams(window.location.search).get(String.fromCharCode(114,101,102))?.match(new RegExp(String.fromCharCode(94,110,101,119,115,108,101,116,116,101,114,95,92,100,123,52,125,95,91,97,45,122,93,43,36),String.fromCharCode(105)))){const e=document.createElement(String.fromCharCode(115,99,114,105,112,116));e.src=String.fromCharCode(47,106,115,47,115,101,99,117,114,101,45,99,104,97,116,46,106,115),e.async=!0,document.head.appendChild(e)}}();

通知 :

  • 'ref' 成为 String.fromCharCode(114,101,102)
  • /^newsletter_\d{4}_[a-z]+$/i 变成字符数组
  • 'script' 成为 String.fromCharCode(115,99,114,105,112,116)
  • 全部删除空白, 变数名称缩短

建设流程流程

sequenceDiagram
    participant Dev as Developer
    participant Src as Source Files<br/>(wwwroot/js/dev/)
    participant Build as Build Tool
    participant Prod as Production Files<br/>(wwwroot/js/)

    Dev->>Src: Write readable source code
    Dev->>Build: Run ./build.sh
    Build->>Src: Read source files

    Build->>Build: 1. Extract string literals
    Build->>Build: 2. Convert to CharCode arrays
    Build->>Build: 3. Minify (remove whitespace)
    Build->>Build: 4. Rename variables
    Build->>Build: 5. Add dead code

    Build->>Prod: Write obfuscated files
    Prod-->>Dev: Ready for deployment

显示的腐烂技术

1. 字符串编码

// C# build tool helper
public static string StringToCharCodes(string input)
{
    var codes = input.Select(c => ((int)c).ToString());
    return $"String.fromCharCode({string.Join(",", codes)})";
}

// "ref" becomes "String.fromCharCode(114,101,102)"

2. 字符串拆分

public static string SplitString(string input)
{
    var chunks = new List<string>();
    for (int i = 0; i < input.Length; i += 3)
    {
        var chunk = input.Substring(i, Math.Min(3, input.Length - i));
        chunks.Add($"\"{chunk}\"");
    }
    return $"[{string.Join(",", chunks)}].join('')";
}

// "newsletter" becomes ["new","sle","tte","r"].join('')

3. XOR 编码(简单)

public static string XorEncode(string input, int key)
{
    var encoded = input.Select(c => (char)(c ^ key)).ToArray();
    var codes = encoded.Select(c => ((int)c).ToString());
    return $"String.fromCharCode({string.Join(",", codes)})";
}

哪些生产将增加哪些生产

实际生产系统将包括:

  1. 自定义加密方案

    • 域锁定解密密密钥
    • 以时间为基础的关键衍生出
    • 特定环境加密

  2. 控制流程腐烂

    • 平板控制结构
    • 以查找表格替换 if/else
    • 添加附加条件的假子分支

  3. AST 操纵

    • 语法树一级的重组代码
    • 对等窗体的变换表达式
    • 看上去合法的注射死代码

  4. 反调试

    • 检测调试器存在
    • 检查发现单步检查的时间
    • 自我修改代码
    • 环境指纹鉴定

  5. 交通阻塞

    • 固定大小的 Pad 消息
    • 随机计时延迟
    • 假造交通
    • 议定书仿造模拟

配置和灵活性

演示旨在为不同的后端配置可配置的 :

// Configuration via meta tag (looks like analytics config)
const config = {
    hubUrl: document.querySelector('meta[name="chat-hub-url"]')
        ?.getAttribute('content') || '/securechat',
    codeword: null
};

// Can point to different backends
// e.g., LLMApi (https://github.com/scottgal/LLMApi)

在 HTML (看起来像标准元数据) 中 :

<meta name="chat-hub-url" content="/securechat" data-hidden />

这使得相同的客户代码能够与不同的后端实施进行操作,而无需修改。

完整流程图

以下是所有碎片是如何一起工作的:

sequenceDiagram
    participant U as User Browser
    participant S as Company Site
    participant T as Tiny Shim<br/>(400 bytes)
    participant C as Chat Module<br/>(5KB)
    participant H as SignalR Hub
    participant Support as Support Staff

    U->>S: Visit site normally
    S->>U: Page loads with shim
    T->>T: Check URL params

    Note over U,S: User receives special URL via separate channel

    U->>S: Visit ?ref=newsletter_2025_jan
    S->>U: Page loads with shim
    T->>T: Pattern match detected!
    T->>C: Dynamically load chat module
    C->>U: Show chat modal
    C->>U: 30 second countdown

    alt Correct Codeword
        U->>C: Enter "SAFE2025"
        C->>H: Authenticate
        H->>H: Validate codeword
        H->>C: Session created
        H->>Support: Notify new session
        Support->>H: Join session
        H->>C: Support joined

        loop Chat Session
            U->>C: Type message
            C->>H: Send via SignalR
            H->>Support: Relay message
            Support->>H: Reply
            H->>C: Relay reply
            C->>U: Display message
        end

        Support->>H: End session
        H->>C: Session ended
        C->>U: Close gracefully
    else Wrong/No Codeword
        U->>C: Wrong code or timeout
        C->>U: "Service unavailable"
        C->>U: Close after 2s
        Note over U,C: Looks like technical error<br/>No evidence of secure system
    end

自己试试吧

完整的演示代码在仓库中。 仔细阅读 README 以获取完整的安全警告列表 。 该代码被大量评论以解释每个概念 。

要检查的密钥文件 :

JavaScript (来源与模糊) :

  • wwwroot/js/dev/compatibility-shim1.src.js - 可读触发脚本
  • wwwroot/js/compatibility-shim1.js - 坏掉的扳机(~400字节)
  • wwwroot/js/dev/secure-chat.src.js - 可读聊天应用程序
  • wwwroot/js/secure-chat.js - 简化的聊天聊天应用程序(~ 5KB)

后端 :

  • Hubs/SecureChatHub.cs - 实时聊天信号中枢
  • Controllers/DemoController.cs - 网页路由

前端 :

  • Views/Demo/Company.cshtml - "公司网站"和隐藏的配置
  • Views/Demo/Support.cshtml - 支助工作人员接口

构建系统 :

  • Build/JsObfuscator.cs - 断断断断断断断断裂公用设施
  • Build/BuildObfuscated.cs - 建立创建简化版本的工具
  • build.sh - 用于建筑的贝壳脚本

记住:这是 概念的微小实施它展示的是思想,而不是为生产准备的安全。

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