PHP encryption function—md5() function encryption example usage

PHP encryption function—md5() function encryption

What is the MD5() function?

The MD5() function is the MD5 hash value of the calculator string, using the MD5 algorithm. The full name of MD5 is Message-Digest Algorithm 5. Its function is to pass data information of different lengths through A series of algorithms are calculated into a 128-bit value, which is to turn a byte string of any length into a large integer of a certain length. Note that this is "byte string", not "string", because this transformation is only related to the byte value and has nothing to do with the character set or encoding method.

We introduced you to the PHP encryption function—crypt() functionencryption in the previous chapter. I believe you already have some understanding of the PHP encryption function. Today, we will give you a detailed introduction to the PHP encryption function—md5() function encryption.

First let’s take a look at the syntax structure of the MD5() function:

string md5(string str[,bool raw_output]);

Among them, the string str is the plaintext to be encrypted. If the rew_output parameter is set to true, then the function will return a Ciphertext in binary form. This parameter defaults to false.

In many websites, the password for registered username is encrypted using MD5, and then saved to the database. When the username is logged in, the program calculates the area entered by the user into an MD5 value, and then Compare it with the MD5 value saved in the database. During this process, the program itself will not "know" the user's real password, thus ensuring the personal privacy of the Zushu user and improving security.

The following example implements the registration and login functions. After encrypting by MD5, the database is saved. The specific steps are as follows:

Step 1: Create conn.php file, complete the link with the database:

<?php
header("Content-Type:text/html; charset=utf-8");
$conn =mysql_connect("localhost","root","root")or die("数据库连接失败".mysql_error());//连接服务器
mysql_select_db("这里是你的数据库名",$conn);//连接数据库
mysql_query("set name gb2312");//设置编码格式
?>

Second step: Create the member registration page, which is the register.php file. In this file, first create the form form, through The register() method verifies the form element value, then adds the form element, completes the submission of the user name and password, and finally submits the data in the form to the register_ok.php file, completing the submission of registration information through an object-oriented method, here I won’t post the code!

The third step: is to create the register_ok.php file, obtain the data in the form, encrypt the password through the MD5() function, and use the object-oriented method to complete. The reference code is as follows:

<?php
header("Content-Type:text/html; charset=utf-8");
class chkinput{                //定义 chkinput类
    var $name;                       //定义成员变量
    var $pwd;                      //定义成员变量
    function chkinput($x,$y){    //定义成员方法
        $this -> name =$x;           //为变量赋值
        $this -> pwd = $y;            //为变量赋值
    }
    function checkinput(){             //定义方法
        include "conn/conn.php";           //调用文件
        $info = mysql_query("insert into 这里是数据库名(user,password)value(‘“.$this -> name.&#39;",&#39;".$this -> pwd.&#39;")");
if($info == false){
    echo "<script language=&#39;javascript&#39;>alert(&#39;会员注册失败&#39;);history.back();</script>";
    exit();
}else{
    $_SESSION[admin_name]=$this ->name;
    echo "<script language=&#39;javascript&#39;>alert(&#39;会员注册成功&#39;);window.location,href=&#39;index.php&#39;;</script>";
}
}
}
$obj = new chkinput(trim($_POST[name]),trim(md5($_POST[pwd]))); //实例化类
$obj -> checkinput();                                             //返回
?>

Step 4: Create index.php and index_ok.php files to implement the login function. I won’t paste the code here!

After completion, you can view the encrypted password in the database!

In the next article, I will introduce a function similar to the MD5() function, sha1(). For details, please read "PHP Encryption Function—sha1() Function Encryption"!

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