HttpSecureCookie, A Way to Encrypt Cookies with ASP.NET 2.0

本文介绍了一个用于保护 ASP.NET 应用程序中 Cookies 的库 HttpSecureCookie,该库利用反射访问了内部类 CookieProtectionHelper,实现了 Cookies 的加密与防篡改。

Introduction

I really have some good laughs when I tamper with cookies on my machine and watch the results when it is submitted back to the site. On the other hand, I don’t want any one to do the same to the cookies that I make!

Cookies, most of the times, shouldn’t be in plain text, at least, they should be tamper-proof! Revealing the content of your cookies might give curious and malicious people an idea about your application’s architecture, and that might help hacking it.

ASP.NET encodes and hashes its authorization ticket, making it secure and tamper-proof. However, the methods used to secure authorization cookies are inaccessible from outside the .NET framework libraries, so you can’t protect your own cookie using these methods; you need to protect it yourself using your own encryption key, encoding and hashing algorithms. HttpSecureCookie works around this by accessing the same methods ASP.NET uses for cookie authorization.

Of course, you shouldn’t save valuable information in your cookies, but if you have to, then this library is at your disposal.

Background

Before you start using this code, if you do not know what MachineKey is, I highly recommend checking this MSDN article: How To: Configure MachineKey in ASP.NET 2.0.

ASP.NET uses the System.Web.Security.CookieProtectionHelper internal class to decode and encode the content of a cookie before submitting it to the client. This class is based on the MachineKey. I wonder why Microsoft kept this class internal!?

To be able to access this internal class, I had to use reflection to be able to access the Decode and Encode methods of CookieProtectionHelper.

Eric Newton has a similar and good article on CP: Encrypting cookies to prevent tampering. However, that code is made for .NET 1.1 and it doesn't work with .NET 2.0 (but it does with some modifications); moreover, its resulting cipher text is in binary format versus being in encrypted format, and I don't know if this is a security risk. Also, I am accessing a higher level class System.Web.Security.CookieProtectionHelper than the one used by that article, System.Web.Configuration.MachineKey, to obtain the cryptography service, and that saved me time by not writing some low level code.

There is also another available method for encoding cookies, by using the FormsAuthenticationTicket and FormsAuthentication.Encrypt; for more information, check the section "Creating the Forms Authentication Cookie" on Explained: Forms Authentication in ASP.NET 2.0. However, I believe, the method mentioned in this article is more flexible.

Obtaining Reference to the CookieProtectionHelper Class via Reflection

To be able to access System.Web.Security.CookieProtectionHelper, I had to create a wrapper class CookieProtectionHelperWrapper which uses reflection to obtain a reference to the underlying methods and exposes the same methods as of the original class:

public static class CookieProtectionHelperWrapper {

    private static MethodInfo _encode;
    private static MethodInfo _decode;

    static CookieProtectionHelperWrapper() {
        // obtaining a reference to System.Web assembly
        Assembly systemWeb = typeof(HttpContext).Assembly;
        if (systemWeb == null) {
            throw new InvalidOperationException(
                "Unable to load System.Web.");
        }
        // obtaining a reference to the internal class CookieProtectionHelper
        Type cookieProtectionHelper = systemWeb.GetType(
                "System.Web.Security.CookieProtectionHelper");
        if (cookieProtectionHelper == null) {
            throw new InvalidOperationException(
                "Unable to get the internal class CookieProtectionHelper.");
        }
        // obtaining references to the methods of CookieProtectionHelper class
        _encode = cookieProtectionHelper.GetMethod(
                "Encode", BindingFlags.NonPublic | BindingFlags.Static);
        _decode = cookieProtectionHelper.GetMethod(
                "Decode", BindingFlags.NonPublic | BindingFlags.Static);

        if (_encode == null || _decode == null) {
            throw new InvalidOperationException(
                "Unable to get the methods to invoke.");
        }
    }

    public static string Encode(CookieProtection cookieProtection, 
                                byte[] buf, int count) {
        return (string)_encode.Invoke(null, 
                new object[] { cookieProtection, buf, count });
    }

    public static byte[] Decode(CookieProtection cookieProtection, 
                                string data) {
        return (byte[])_decode.Invoke(null, 
                new object[] { cookieProtection, data });
    }

}

MachineKeyCryptography: A Cryptography Class Based on MachineKey

MachineKeyCryptography is a static class that provides text ciphering and tamper-proofing services, it provides higher level access to CookieProtectionHelperWrapper. So, if you want to cipher any text based on the machine key, this class is the right one to use.

public static string Encode(string text, CookieProtection cookieProtection) {
    if (string.IsNullOrEmpty(text) || cookieProtection == CookieProtection.None) {
        return text;
    }
    byte[] buf = Encoding.UTF8.GetBytes(text);
    return CookieProtectionHelperWrapper.Encode(cookieProtection, buf, buf.Length); 
}

public static string Decode(string text, CookieProtection cookieProtection) {
    if (string.IsNullOrEmpty(text)) {
        return text;
    }
    byte[] buf;
    try {
        buf = CookieProtectionHelperWrapper.Decode(cookieProtection, text);
    }
    catch(Exception ex) {
        throw new InvalidCypherTextException(
            "Unable to decode the text", ex.InnerException);
    }
    if (buf == null || buf.Length == 0) {
        throw new InvalidCypherTextException(
            "Unable to decode the text");
    }
    return Encoding.UTF8.GetString(buf, 0, buf.Length);
}

HttpSecureCookie Class

This static class will handle the service of securing the content of a cookie. Also, it provides a service to clone a cookie. This class uses MachineKeyCryptography internally to provide crypting services:

public static class HttpSecureCookie {

    public static HttpCookie Encode(HttpCookie cookie) {
        return Encode(cookie, CookieProtection.All);
    }

    public static HttpCookie Encode(HttpCookie cookie, 
                  CookieProtection cookieProtection) {
        HttpCookie encodedCookie = CloneCookie(cookie);
        encodedCookie.Value = 
          MachineKeyCryptography.Encode(cookie.Value, cookieProtection);
        return encodedCookie;
    }

    public static HttpCookie Decode(HttpCookie cookie) {
        return Decode(cookie, CookieProtection.All);
    }

    public static HttpCookie Decode(HttpCookie cookie, 
                  CookieProtection cookieProtection) {
        HttpCookie decodedCookie = CloneCookie(cookie);
        decodedCookie.Value = 
          MachineKeyCryptography.Decode(cookie.Value, cookieProtection);
        return decodedCookie;
    }

    public static HttpCookie CloneCookie(HttpCookie cookie) {
        HttpCookie clonedCookie = new HttpCookie(cookie.Name, cookie.Value);
        clonedCookie.Domain = cookie.Domain;
        clonedCookie.Expires = cookie.Expires;
        clonedCookie.HttpOnly = cookie.HttpOnly;
        clonedCookie.Path = cookie.Path;
        clonedCookie.Secure = cookie.Secure;

        return clonedCookie;
    }
}

Using the Code

Using HttpSecureCookie is easy; for a complete demo, please check the sample application. To encode a cookie:

HttpCookie cookie = new HttpCookie("UserName", "Terminator");
cookie.Expires = DateTime.Now.AddDays(1);
HttpCookie encodedCookie = HttpSecureCookie.Encode(cookie);
Response.Cookies.Add(encodedCookie);

To decode an encoded cookie:

HttpCookie cookie = Request.Cookies["UserName"];
lblDisplayBefore.Text = cookie.Value;
HttpCookie decodedCookie = HttpSecureCookie.Decode(cookie);

To use HttpSecureCookie on a web farm, you need to set the correct MachineKey configuration in Web.Config. For more information, check the "Web Farm Deployment Considerations" section on How To: Configure MachineKey in ASP.NET 2.0. To generate a machine key, please check How to create keys by using Visual C# .NET for use in Forms authentication.

Limitations

This library uses reflection, so it might break with the next version of .NET. Also, it doesn't work with .NET 1.1.

Reflection might have some performance implication; however, I used an assembly that is already loaded, "System.Web.dll", and I am only using reflection once across the life time of the application, to gain extra performance.

Conclusion

If you don't want a sophisticated cookie encryption service, if you don't want to mind the encryption key, and if you don't want to create your own encryption algorithm, then this library is for you!

Comments and suggestions are welcome. Please vote if you like this article (or if you didn't).

标题SpringBoot智能在线预约挂号系统研究AI更换标题第1章引言介绍智能在线预约挂号系统的研究背景、意义、国内外研究现状及论文创新点。1.1研究背景与意义阐述智能在线预约挂号系统对提升医疗服务效率的重要性。1.2国内外研究现状分析国内外智能在线预约挂号系统的研究与应用情况。1.3研究方法及创新点概述本文采用的技术路线、研究方法及主要创新点。第2章相关理论总结智能在线预约挂号系统相关理论,包括系统架构、开发技术等。2.1系统架构设计理论介绍系统架构设计的基本原则和常用方法。2.2SpringBoot开发框架理论阐述SpringBoot框架的特点、优势及其在系统开发中的应用。2.3数据库设计与管理理论介绍数据库设计原则、数据模型及数据库管理系统。2.4网络安全与数据保护理论讨论网络安全威胁、数据保护技术及其在系统中的应用。第3章SpringBoot智能在线预约挂号系统设计详细介绍系统的设计方案,包括功能模块划分、数据库设计等。3.1系统功能模块设计划分系统功能模块,如用户管理、挂号管理、医生排班等。3.2数据库设计与实现设计数据库表结构,确定字段类型、主键及外键关系。3.3用户界面设计设计用户友好的界面,提升用户体验。3.4系统安全设计阐述系统安全策略,包括用户认证、数据加密等。第4章系统实现与测试介绍系统的实现过程,包括编码、测试及优化等。4.1系统编码实现采用SpringBoot框架进行系统编码实现。4.2系统测试方法介绍系统测试的方法、步骤及测试用例设计。4.3系统性能测试与分析对系统进行性能测试,分析测试结果并提出优化建议。4.4系统优化与改进根据测试结果对系统进行优化和改进,提升系统性能。第5章研究结果呈现系统实现后的效果,包括功能实现、性能提升等。5.1系统功能实现效果展示系统各功能模块的实现效果,如挂号成功界面等。5.2系统性能提升效果对比优化前后的系统性能
在金融行业中,对信用风险的判断是核心环节之一,其结果对机构的信贷政策和风险控制策略有直接影响。本文将围绕如何借助机器学习方法,尤其是Sklearn工具包,建立用于判断信用状况的预测系统。文中将涵盖逻辑回归、支持向量机等常见方法,并通过实际操作流程进行说明。 一、机器学习基本概念 机器学习属于人工智能的子领域,其基本理念是通过数据自动学习规律,而非依赖人工设定规则。在信贷分析中,该技术可用于挖掘历史数据中的潜在规律,进而对未来的信用表现进行预测。 二、Sklearn工具包概述 Sklearn(Scikit-learn)是Python语言中广泛使用的机器学习模块,提供多种数据处理和建模功能。它简化了数据清洗、特征提取、模型构建、验证与优化等流程,是数据科学项目中的常用工具。 三、逻辑回归模型 逻辑回归是一种常用于分类任务的线性模型,特别适用于二类问题。在信用评估中,该模型可用于判断借款人是否可能违约。其通过逻辑函数将输出映射为0到1之间的概率值,从而表示违约的可能性。 四、支持向量机模型 支持向量机是一种用于监督学习的算法,适用于数据维度高、样本量小的情况。在信用分析中,该方法能够通过寻找最佳分割面,区分违约与非违约客户。通过选用不同核函数,可应对复杂的非线性关系,提升预测精度。 五、数据预处理步骤 在建模前,需对原始数据进行清理与转换,包括处理缺失值、识别异常点、标准化数值、筛选有效特征等。对于信用评分,常见的输入变量包括收入水平、负债比例、信用历史记录、职业稳定性等。预处理有助于减少噪声干扰,增强模型的适应性。 六、模型构建与验证 借助Sklearn,可以将数据集划分为训练集和测试集,并通过交叉验证调整参数以提升模型性能。常用评估指标包括准确率、召回率、F1值以及AUC-ROC曲线。在处理不平衡数据时,更应关注模型的召回率与特异性。 七、集成学习方法 为提升模型预测能力,可采用集成策略,如结合多个模型的预测结果。这有助于降低单一模型的偏差与方差,增强整体预测的稳定性与准确性。 综上,基于机器学习的信用评估系统可通过Sklearn中的多种算法,结合合理的数据处理与模型优化,实现对借款人信用状况的精准判断。在实际应用中,需持续调整模型以适应市场变化,保障预测结果的长期有效性。 资源来源于网络分享,仅用于学习交流使用,请勿用于商业,如有侵权请联系我删除!
评论
添加红包

请填写红包祝福语或标题

红包个数最小为10个

红包金额最低5元

当前余额3.43前往充值 >
需支付:10.00
成就一亿技术人!
领取后你会自动成为博主和红包主的粉丝 规则
hope_wisdom
发出的红包
实付
使用余额支付
点击重新获取
扫码支付
钱包余额 0

抵扣说明:

1.余额是钱包充值的虚拟货币,按照1:1的比例进行支付金额的抵扣。
2.余额无法直接购买下载,可以购买VIP、付费专栏及课程。

余额充值