內容簡介
Really Simple CAPTCHA 是一款簡單的 CAPTCHA 解決方案，主要用於與其他外掛搭配使用，特別是 Contact Form 7。它透過生成圖片和文本檔案來驗證使用者的回應，雖然安全性不高，但操作簡單，適合基本需求。
【主要功能】
• 與其他外掛兼容使用
• 生成圖片和文本檔案進行驗證
• 使用隨機字詞作為 CAPTCHA
外掛標籤
開發者團隊
原文外掛簡介
Really Simple CAPTCHA does not work alone and is intended to work with other plugins. It is originally created for Contact Form 7, however, you can use it with your own plugin.
Note: This product is “really simple” as its name suggests, i.e., it is not strongly secure. If you need perfect security, you should try other solutions.
How does it work?
Really Simple CAPTCHA does not use PHP “Sessions” for storing states, unlike many other PHP CAPTCHA solutions, but stores them as temporary files. This allows you to embed it into WordPress without worrying about conflicts.
When you generate a CAPTCHA, Really Simple CAPTCHA creates two files for it; one is an image file of CAPTCHA, and the other is a text file which stores the correct answer to the CAPTCHA.
The two files have the same (random) prefix in their file names, for example, “a7hk3ux8p.png” and “a7hk3ux8p.txt.” In this case, for example, when the respondent answers “K5GF” as an answer to the “a7hk3ux8p.png” image, then Really Simple CAPTCHA calculates hash of “K5GF” and tests it against the hash stored in the “a7hk3ux8p.txt” file. If the two match, the answer is confirmed as correct.
How to use with your plugin
Note: Below are instructions for plugin developers.
First, create an instance of ReallySimpleCaptcha class:
$captcha_instance = new ReallySimpleCaptcha();
You can change the instance variables as you wish.
// Change the background color of CAPTCHA image to black
$captcha_instance->bg = array( 0, 0, 0 );
See really-simple-captcha.php if you are interested in other variables.
Generate a random word for CAPTCHA.
$word = $captcha_instance->generate_random_word();
Generate an image file and a corresponding text file in the temporary directory.
$prefix = wp_rand();
$captcha_instance->generate_image( $prefix, $word );
Then, show the image and get an answer from respondent.
Check the correctness of the answer.
$correct = $captcha_instance->check( $prefix, $the_answer_from_respondent );
If the $correct is true, go ahead. Otherwise, block the respondent — as it would appear not to be human.
And last, remove the temporary image and text files, as they are no longer in use.
$captcha_instance->remove( $prefix );
That’s all.
If you wish to see a live sample of this, you can try Contact Form 7.
