AnQiCMS (AnQiCMS) is an enterprise-level content management system developed based on the Go language, which has a unique design in providing efficient and secure content management solutions.In daily website operations, captcha is an important defense line against automated script attacks, preventing spam and ensuring data security.How does AnQiCMS cleverly handle the captcha request and verification logic from the perspective of a developer?Let's delve into the underlying operational mechanism.

Captcha: A digital defense line

Before delving into the backend logic, let's clarify the application scenarios of the captcha in AnQiCMS.The captcha is mainly used for interactive elements that require manual input by users, such as leaving messages and comments, as indicated by the document.Its core goal is to distinguish between human users and automated programs, thus effectively preventing malicious flooding, brute force attacks, or spam comments and other behaviors.

第一步：Verification code generation and request

When the user visits a page that requires a captcha, such as a message board or comment section, the front-end JavaScript code will initiate the captcha request process.This process usually initiates a specific API call to the backend through an asynchronous request (AJAX).

In AnQiCMS, the front-end template (such astag-/anqiapi-other/167.htmlas shown in the middle) will send to/api/captchaThis interface initiates a GET request. Once the backend receives this request, the Go language core of AnQiCMS will start to perform the following key operations:

  1. Generate a unique identifier:The backend will first generate a globally unique verification code ID (captcha_id). This ID is the "ID card" of this verification code session, used to identify which verification code it is during subsequent verification.
  2. Generate captcha content:Next, the backend will generate the actual content of the captcha based on preset strategies (such as random alphanumeric combinations, simple math problems, etc.).To enhance security, this content often includes certain interference elements, such as random lines, dots, color gradients, and even distorted or transformed characters, making it difficult for OCR (Optical Character Recognition) technology to crack.
  3. Store captcha:The generated captcha content will not be directly exposed to the front-end, but will be encrypted or hashed with the previous generatedcaptcha_idAssociate and temporarily store in some place on the server.This is usually a time-sensitive cache system (such as Redis) or server memory to ensure that the captcha automatically expires after a certain period of time, preventing replay attacks.Since AnQiCMS is written in Go language, its high concurrency features ensure efficient and stable processing of a large number of captcha generation and storage requests.
  4. Return captcha data:Finally, the backend willcaptcha_idand return the captcha image (usually Base64 encoded image data or image URL) together with the front-end. The JavaScript on the front-end can then dynamically display the captcha image on the page, andcaptcha_idStored in a hidden field, waiting for user input.

Step 2: User input and backend validation

The user entered the captcha on the front-end interface and submitted the form, then the back-end will receive including the captcha filled in by the user (captcha) and the one obtained previouslycaptcha_id。At this time, the backend validation logic of AnQiCMS will be triggered:

  1. Data reception and extraction:The backend service receives the submitted form data and extracts it safely from the request,captcha_idand the value entered by thecaptchavalue.
  2. Get the original verification code:Then, the backend will use the receivedcaptcha_idto query the corresponding original verification code content in its temporary storage. Ifcaptcha_idInvalid (possibly expired or tampered with), then the verification will fail directly.
  3. Comparison and verification:The core verification process begins here.The backend will compare the user input captcha with the stored original captcha.To enhance user experience, this comparison process usually ignores case, but high-security scenarios may distinguish it strictly.
    • Match successful:If both are consistent, then the captcha verification passes. At this point, in order to prevent thecaptcha_idRepeated for malicious submission (i.e., replay attack), the backend will immediately delete it from storagecaptcha_idThe corresponding verification code content. Then, the normal business logic (such as saving messages or comments) will continue to execute.
    • Match failed:If both are not the same, the captcha verification will fail.The backend will return the corresponding error information to the frontend, prompting the user to re-enter.This usually does not result in the loss of user data, but the user needs to correct the captcha part.
  4. Security mechanism:AnQiCMS on the strong performance foundation of Go language, can add more security strategies to captcha verification, such as limiting the number of times the same IP or user submits a captcha within a short period of time, or locking the account or increasing the difficulty after multiple failures, in order to further enhance the system's anti-attack ability.

The Practice of AnQiCMS

AnQiCMS fully demonstrates its design philosophy of 'efficient, customizable, and easy to expand' in handling captcha.

  • Flexible configuration:The administrator can easily enable or disable the captcha function in the background without modifying the code, reflecting AnQiCMS's ability to respond to operational needs.
  • API-driven:The generation and verification of captcha are realized through clear API interfaces, allowing the front-end to integrate and display flexibly. Whether it is traditional form submission or modern SPA (Single Page Application) architecture, it can be easily connected.
  • Performance Assurance:As a CMS based on Go language, AnQiCMS can take advantage of the lightweight concurrency of Goroutine to ensure quick response in handling high-concurrency captcha requests, and not become a bottleneck of the system.
  • Safety consideration:Fromcaptcha_idThe generation, storage strategy of captcha content, to the immediate invalidation after the verification is successful, AnQiCMS has considered common security vulnerabilities and strives to provide a robust verification mechanism.

Through such a mechanism, AnQiCMS can not only effectively prevent the malicious behavior of automated programs, but also provide a smooth and secure interactive experience for real users, thereby ensuring the quality and stability of the entire website content.

Common Questions (FAQ)

1. Why does my website enable captcha but it doesn't show on the front end?The backend of AnQiCMS enables the captcha function, which only allows the captcha logic to run, but the front-end template still needs to add the corresponding code to request and render the captcha. You need to check if the front-end message or comment template includestag-/anqiapi-other/167.htmlThe JavaScript and HTML code provided in the document ensures that the request and display logic for the captcha is correctly integrated.

2. Does AnQiCMS support custom styles for captcha or can it be replaced with other types of captcha (such as slider captcha, SMS verification)?AnQiCMS currently provides default picture captcha. Although you can use the provided template code (tag-/anqiapi-other/167.html）通过CSS自定义验证码图片的外观样式，但如果需要更换为其他更复杂的验证码类型（如行为验证、滑块验证、短信验证等），则通常需要进行二次开发，集成第三方验证码服务商的API，并修改AnQiCMS后端相应的生成和验证逻辑。The modular design and Go language features of AnQiCMS provide a good foundation for this customization.

3. What are the countermeasures taken by the AnQiCMS backend if the user enters the wrong verification code multiple times in a row?In most cases, AnQiCMS will simply prompt the user to re-enter and refresh the captcha after the captcha verification fails.But as an enterprise-level system, the AnQiCMS backend can be configured with more strict security policies, such as for continuous multiple captcha failure behaviors from the same IP or user, which may trigger temporary IP blocking, limiting submission frequency, or recording abnormal behaviors in logs for further review by administrators, thus effectively preventing brute force attacks by malicious programs.The specific implementation details may vary depending on the version of AnQiCMS and the integration of additional security modules.