search
HomeBackend DevelopmentPHP TutorialFunction introduction of PHP function crypt()_PHP tutorial

Function introduction of PHP function crypt()_PHP tutorial

Jul 15, 2016 pm 01:30 PM
cryptphpintroducefunctionFunctionencryptionaccomplishusdatayesof

We know that there is a function to implement data encryption in PHP. What we will introduce to you today is one of the functions that can implement data encryption function - PHP function crypt(). As an example of the PHP function crypt(), consider a situation where you wish to create a PHP script that restricts access to a directory to only users who can provide the correct username and password.

I will store the data in a table in MySQL, my favorite database. Let's start our example by creating the table called members:

<ol class="dp-xml">
<li class="alt"><span><span>mysql</span><span class="tag">></span><span>CREATE TABLE members (   </span></span></li>
<li>
<span>-</span><span class="tag">></span><span>username CHAR(14) NOT NULL,   </span>
</li>
<li class="alt">
<span>-</span><span class="tag">></span><span>password CHAR(32) NOT NULL,   </span>
</li>
<li>
<span>-</span><span class="tag">></span><span>PRIMARY KEY(username)   </span>
</li>
<li class="alt">
<span>-</span><span class="tag">></span><span>);  </span>
</li>
</ol>

Then, we assume that the following data is already stored in the table:

Username Password
clark keloD1C377lKE
bruce ba1T7vnz9AWgk
peter paLUvRWsRLZ4U

The plain codes corresponding to these encrypted passwords in the PHP function crypt() are kent, banner and parker respectively. Pay attention to the first two letters of each password. This is because I used the following code to create a interference string based on the first two letters of the password:

<ol class="dp-xml">
<li class="alt"><span><span>$enteredPassword.   </span></span></li>
<li>
<span>$</span><span class="attribute">salt</span><span> = </span><span class="attribute-value">substr</span><span>($enteredPassword, 0, 2);   </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">userPswd</span><span> = </span><span class="attribute-value">crypt</span><span>($enteredPassword, $salt);   </span>
</li>
<li><span>// $userPswd然后就和用户名一起存储在MySQL 中  </span></li>
</ol>

I will be using Apache's password-response authentication configuration to prompt the user for a username and password. A little known fact about PHP is that it can recognize the username and password entered by the Apache password-response system as $PHP_AUTH_USER and $PHP_AUTH_PW, I will use these two variables in the authentication script. Take some time to read the following script carefully and pay more attention to the explanations to better understand the following code:

Application of PHP function crypt() and Apache's password-response verification system

<ol class="dp-xml">
<li class="alt"><span><span class="tag"><span> ?php   </span></span></span></li>
<li>
<span>$</span><span class="attribute">host</span><span> = </span><span class="attribute-value">"localhost"</span><span>;   </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">user</span><span> = </span><span class="attribute-value">"zorro"</span><span>;   </span>
</li>
<li>
<span>$</span><span class="attribute">pswd</span><span> = </span><span class="attribute-value">"hell odolly"</span><span>;   </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">db</span><span> = </span><span class="attribute-value">"users"</span><span>;   </span>
</li>
<li><span>// Set authorization to False   </span></li>
<li class="alt">
<span>$</span><span class="attribute">authorization</span><span> = </span><span class="attribute-value">0</span><span>;   </span>
</li>
<li><span>// Verify that user has entered<br> username and password   </span></li>
<li class="alt"><span>if (isset($PHP_AUTH_USER) && <br>isset($PHP_AUTH_PW)) :   </span></li>
<li><span>mysql_pconnect($host, $user, <br>$pswd) or die("Can't connect to MySQL   </span></li>
<li class="alt"><span>server!");   </span></li>
<li><span>mysql_select_db($db) or die<br>("Can't select database!");   </span></li>
<li class="alt"><span>// Perform the encryption   </span></li>
<li>
<span>$</span><span class="attribute">salt</span><span> = </span><span class="attribute-value">substr</span><span>($PHP_AUTH_PW, 0, 2);   </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">encrypted_pswd</span><span> = crypt($PHP_AUTH_PW, $salt);   </span>
</li>
<li><span>// Build the query   </span></li>
<li class="alt">
<span>$</span><span class="attribute">query</span><span> = "SELECT username FROM members WHERE   </span>
</li>
<li>
<span class="attribute">username</span><span> = '$PHP_AUTH_USER' AND   </span>
</li>
<li class="alt">
<span class="attribute">password</span><span> = '$encrypted_pswd'";   </span>
</li>
<li><span>// Execute the query   </span></li>
<li class="alt"><span>if (mysql_numrows(mysql_query($query)) == 1) :   </span></li>
<li>
<span>$</span><span class="attribute">authorization</span><span> = </span><span class="attribute-value">1</span><span>;   </span>
</li>
<li class="alt"><span>endif;   </span></li>
<li><span>endif;   </span></li>
<li class="alt"><span>// confirm authorization   </span></li>
<li><span>if (! $authorization) :   </span></li>
<li class="alt">
<span>header('WWW-Authenticate: <br>Basic </span><span class="attribute">realm</span><span>=</span><span class="attribute-value">"Private"</span><span>');   </span>
</li>
<li><span>header('HTTP/1.0 401 Unauthorized');   </span></li>
<li class="alt"><span>print "You are unauthorized <br>to enter this area.";   </span></li>
<li><span>exit;   </span></li>
<li class="alt"><span>else :   </span></li>
<li><span>print "This is the secret data!";   </span></li>
<li class="alt"><span>endif;   </span></li>
<li>
<span class="tag">?></span><span>  </span>
</li>
</ol>

The above is a simple authentication system to verify user access rights. When using the PHP function crypt() to protect important confidential information, remember that the PHP function crypt() used by default is not the most secure and can only be used in systems with lower security requirements. If necessary Higher security performance requires the algorithm I introduce later in this article.


www.bkjia.comtruehttp: //www.bkjia.com/PHPjc/446265.htmlTechArticleWe know that there is a function to implement data encryption in. What we will introduce to you today is one of them that can implement data encryption. The function of the encryption function is the PHP function crypt(). As PHP function crypt()...
Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
How can you check if a PHP session has already started?How can you check if a PHP session has already started?Apr 30, 2025 am 12:20 AM

In PHP, you can use session_status() or session_id() to check whether the session has started. 1) Use the session_status() function. If PHP_SESSION_ACTIVE is returned, the session has been started. 2) Use the session_id() function, if a non-empty string is returned, the session has been started. Both methods can effectively check the session state, and choosing which method to use depends on the PHP version and personal preferences.

Describe a scenario where using sessions is essential in a web application.Describe a scenario where using sessions is essential in a web application.Apr 30, 2025 am 12:16 AM

Sessionsarevitalinwebapplications,especiallyfore-commerceplatforms.Theymaintainuserdataacrossrequests,crucialforshoppingcarts,authentication,andpersonalization.InFlask,sessionscanbeimplementedusingsimplecodetomanageuserloginsanddatapersistence.

How can you manage concurrent session access in PHP?How can you manage concurrent session access in PHP?Apr 30, 2025 am 12:11 AM

Managing concurrent session access in PHP can be done by the following methods: 1. Use the database to store session data, 2. Use Redis or Memcached, 3. Implement a session locking strategy. These methods help ensure data consistency and improve concurrency performance.

What are the limitations of using PHP sessions?What are the limitations of using PHP sessions?Apr 30, 2025 am 12:04 AM

PHPsessionshaveseverallimitations:1)Storageconstraintscanleadtoperformanceissues;2)Securityvulnerabilitieslikesessionfixationattacksexist;3)Scalabilityischallengingduetoserver-specificstorage;4)Sessionexpirationmanagementcanbeproblematic;5)Datapersis

Explain how load balancing affects session management and how to address it.Explain how load balancing affects session management and how to address it.Apr 29, 2025 am 12:42 AM

Load balancing affects session management, but can be resolved with session replication, session stickiness, and centralized session storage. 1. Session Replication Copy session data between servers. 2. Session stickiness directs user requests to the same server. 3. Centralized session storage uses independent servers such as Redis to store session data to ensure data sharing.

Explain the concept of session locking.Explain the concept of session locking.Apr 29, 2025 am 12:39 AM

Sessionlockingisatechniqueusedtoensureauser'ssessionremainsexclusivetooneuseratatime.Itiscrucialforpreventingdatacorruptionandsecuritybreachesinmulti-userapplications.Sessionlockingisimplementedusingserver-sidelockingmechanisms,suchasReentrantLockinJ

Are there any alternatives to PHP sessions?Are there any alternatives to PHP sessions?Apr 29, 2025 am 12:36 AM

Alternatives to PHP sessions include Cookies, Token-based Authentication, Database-based Sessions, and Redis/Memcached. 1.Cookies manage sessions by storing data on the client, which is simple but low in security. 2.Token-based Authentication uses tokens to verify users, which is highly secure but requires additional logic. 3.Database-basedSessions stores data in the database, which has good scalability but may affect performance. 4. Redis/Memcached uses distributed cache to improve performance and scalability, but requires additional matching

Define the term 'session hijacking' in the context of PHP.Define the term 'session hijacking' in the context of PHP.Apr 29, 2025 am 12:33 AM

Sessionhijacking refers to an attacker impersonating a user by obtaining the user's sessionID. Prevention methods include: 1) encrypting communication using HTTPS; 2) verifying the source of the sessionID; 3) using a secure sessionID generation algorithm; 4) regularly updating the sessionID.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

Atom editor mac version download

Atom editor mac version download

The most popular open source editor

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.