Verification code usage scenario

In the process of developing the system, basically all systems will involve the login module, of which the verification code function is an indispensable part to prevent the system from being exploded. Effective Ways. As the saying goes, the devil is as high as the road. Nowadays, verification codes are becoming more and more complex and advanced. Common alphanumeric verification codes and behavioral verification codes are common. This article details simple alphanumeric verification codes.

Code

<?php

/*********************************************************************************
 * InitPHP 3.8.2 國(guó)產(chǎn)PHP開(kāi)發(fā)框架   擴(kuò)展類庫(kù)-驗(yàn)證碼
 *-------------------------------------------------------------------------------
 * 版權(quán)所有: CopyRight By initphp.com
 * 您可以自由使用該源碼，但是在使用過(guò)程中，請(qǐng)保留作者信息。尊重他人勞動(dòng)成果就是尊重自己
 *-------------------------------------------------------------------------------
 * Author:zhuli Dtime:2014-11-25
 ***********************************************************************************/
class Code
{

    private $charset = "abcdefghjklmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ23456789";   //隨機(jī)因子
    private $code;     //驗(yàn)證碼文字
    private $codelen = 4;    //驗(yàn)證碼顯示幾個(gè)文字
    private $width = 100;   //驗(yàn)證碼寬度
    private $height = 40;   //驗(yàn)證碼高度
    private $img;       //驗(yàn)證碼資源句柄
    private $font;     //指定的字體
    private $fontsize = 20;  //指定的字體大小
    private $fontcolor;     //字體顏色  隨機(jī)

    //構(gòu)造類  編寫字體
    public function __construct()
    {
        $this->font = &#39;/outputs/font/font.ttf&#39;;
    }

    //創(chuàng)建4個(gè)隨機(jī)碼
    private function createCode()
    {
        $_leng = strlen($this->charset) - 1;
        for ($i = 1; $i <= $this->codelen; $i++) {
            $this->code .= $this->charset[mt_rand(0, $_leng)];
        }
//        session_start();
//        $_SESSION[&#39;VerifyCode&#39;] = strtolower($this->code);
        Session::set(&#39;VerifyCode&#39;, strtolower($this->code));
        return $this->code;
    }

    //創(chuàng)建背景
    private function createBg()
    {
        //創(chuàng)建畫布 給一個(gè)資源jubing
        $this->img = imagecreatetruecolor($this->width, $this->height);
        //背景顏色
        $color = imagecolorallocate($this->img, mt_rand(157, 255), mt_rand(157, 255), mt_rand(157, 255));
        //畫出一個(gè)矩形
        imagefilledrectangle($this->img, 0, $this->height, $this->width, 0, $color);
    }

    //創(chuàng)建字體
    private function createFont()
    {
        $_x = ($this->width / $this->codelen);   //字體長(zhǎng)度
        for ($i = 0; $i < $this->codelen; $i++) {
            //文字顏色
            $color = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
            //資源句柄 字體大小 傾斜度 字體長(zhǎng)度  字體高度  字體顏色  字體  具體文本
            imagettftext($this->img, $this->fontsize, mt_rand(-30, 30), $_x * $i + mt_rand(1, 5), $this->height / 1.4, $color, $this->font, $this->code[$i]);
        }
    }

    //隨機(jī)線條
    private function createLine()
    {
        //隨機(jī)線條
        for ($i = 0; $i < 6; $i++) {
            $color = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
            imageline($this->img, mt_rand(0, $this->width), mt_rand(0, $this->height), mt_rand(0, $this->width), mt_rand(0, $this->height), $color);
        }
        //隨機(jī)雪花
        for ($i = 0; $i < 45; $i++) {
            $color = imagecolorallocate($this->img, mt_rand(220, 255), mt_rand(220, 255), mt_rand(220, 255));
            imagestring($this->img, mt_rand(1, 5), mt_rand(0, $this->width), mt_rand(0, $this->height), &#39;*&#39;, $color);
        }
    }

    //輸出背景
    private function outPut()
    {
        //生成標(biāo)頭
        header(&#39;Content-type:image/png&#39;);
        //輸出圖片
        imagepng($this->img);
        //銷毀結(jié)果集
        imagedestroy($this->img);
    }

    //對(duì)外輸出
    public function doimg()
    {
        //加載背景
        $this->createBg();
        //加載文件
        $this->createCode();
        //加載線條
        $this->createLine();
        //加載字體
        $this->createFont();
        //加載背景
        $this->outPut();
    }

    //獲取驗(yàn)證碼
    public function getCode()
    {
        return strtolower($this->code);
    }

    //驗(yàn)證驗(yàn)證碼
    public function checkCode($code, $clear = false)
    {
//        session_start();
        if (Session::get(&#39;VerifyCode&#39;) == strtolower($code)) {
            if($clear) $this->clearCode();
            return true;
        }
        if($clear) $this->clearCode();
        return false;
    }

    //清除驗(yàn)證碼
    public function clearCode()
    {
        Session::del(&#39;VerifyCode&#39;);
//        session_start();
//        unset ($_SESSION[&#39;VerifyCode&#39;]);
    }
}

Verification

ob_clean();
$verify = new Code();
$verify->doimg();

This will output the following verification code

Parameters can be adjusted to control the size of the verification code, interference items, etc.

Expansion

Next, we will introduce the expansion function, how to strengthen the interference items of the verification code, and how to integrate it into the project for login verification.

1. Strengthen interference

First of all, we can see a few lines in the screenshot above. If outsiders use analysis tools to decode, it will be very simple to solve the problem. To generate our verification code, you need to add the number of lines at this time. Find the following code in the code and modify the number 6 above

//隨機(jī)線條
private function createLine()
{
    //隨機(jī)線條 
    for ($i = 0; $i < 6; $i++) {
        $color = imagecolorallocate($this->img, mt_rand(0, 156), mt_rand(0, 156), mt_rand(0, 156));
        imageline($this->img, mt_rand(0, $this->width), mt_rand(0, $this->height), mt_rand(0, $this->width), mt_rand(0, $this->height), $color);
    }
    //隨機(jī)雪花
    for ($i = 0; $i < 45; $i++) {
        $color = imagecolorallocate($this->img, mt_rand(220, 255), mt_rand(220, 255), mt_rand(220, 255));
        imagestring($this->img, mt_rand(1, 5), mt_rand(0, $this->width), mt_rand(0, $this->height), &#39;*&#39;, $color);
    }
}

. You can adjust it slowly, and then check the effect until you are satisfied. At the same time, you can see that there are many snowflake effects in the verification code. This is also an interference item. You can modify the number 45 above to adjust to a satisfactory result.

Note: The $charset variable in the code, the verification code randomly picks characters from here to survive verification, because the effect of lowercase i and L is difficult to distinguish, So we removed the i character.

2. Access project verification

Create a new file with the following code

Then introduce this into the existing system login page The interface can display the verification code. After the user fills in and submits, the server performs the following verification 
//驗(yàn)證驗(yàn)證碼
public function checkCode($code, $clear = false)
{
    if (Session::get('VerifyCode') == strtolower($code)) {
        if($clear) $this->clearCode();
            return true;
    }
    if($clear) $this->clearCode();
    return false;
}
//清除驗(yàn)證碼
public function clearCode()
{
    Session::del('VerifyCode');
}
 At this point, the verification code generation and verification process have been completed. 
The above is the detailed content of PHP generates graphic verification code (enhanced interference type). For more information, please follow other related articles on the PHP Chinese website!