Practical tutorials on filtering and verification as well as escaping and passwords in php

When we develop applications, we generally have a convention: do not trust any data from data sources that are not under your control. So at this time, the content introduced in this article is used. This article mainly introduces to you the relevant information about filtering, verification, escaping and passwords in PHP practical tutorials. Friends in need can refer to it. Let’s take a look together.

This article mainly introduces to you the content related to filtering, verification, escaping and passwords in PHP practice. It is shared for your reference and study. I won’t say much below, let’s take a look at the details. Introduction:

1. Filtering, verification and escaping

1). Do not trust any data source that is not under your direct control. The data. Including but not limited to:

• $_GET

• $_POST

• $_REQUEST

• $_COOKIE

• $argv

• php://stdin

• php://input

• file_get_contents()

• Remote database

• Remote API

• Data from client

2). Solution: Filter input. To remove unsafe characters, data must be filtered before it reaches the application's storage layer. The data that needs to be filtered includes but is not limited to: HTML, SQL queries and user profile information.

• HTML: Use the htmlentities() function to filter HTML into corresponding entities. This function escapes the specified HTML characters for safe rendering at the storage layer. The correct way to use it is to use htmlentities($input, ENT_QUOTES, 'UTF-8') to filter input. Or use HTML Purifier. Disadvantage is slow

• SQL query: Sometimes a SQL query must be constructed based on the data. At this time, you need to use PDO preprocessing statements to filter external data.

• User profile information: Use filter_var() and filter_input() to filter user profile information

3). Verify data: You can also use filter_var(). Successful verification returns the value to be verified, and failure returns false. But this function cannot verify all data, so some verification function components can be used. For example, aura/filter or symfony/validator

4) Escape output: You can still use the htmlentities function, and some template engines also have their own escape functions.

Password

1). Never know the user’s password.

2). Never restrict the user’s password. If you want to restrict it, only limit it to the minimum length.

3). Never use email to send user passwords. You can send a link to change the password with a token to verify that it is the user.

4). Use bcrypt to calculate the hash value of the user password. Encryption and hashing are not the same thing. Encryption is a two-way algorithm and the encrypted data can be decrypted. However, hashing is a single algorithm, and the data after hashing cannot be restored. The data obtained after hashing the same data is always the same. Use a database to store the value after hashing the password with bcrypt.

5). Use the Password Hash API to simplify the operation of calculating password hashes and verifying passwords. The following are the general operations of registered users

POST /register.php HTTP/1.1
Content-Length： 43
Content-type: application/x-www-form-urlencoded

email=xiao@hello.world&password=nihao

The following is the PHP file that accepts this request

##

<?php
try {
 $email = filter_input(INPUT_POST, &#39;email&#39;, FILTER_VALIDATE_EMAIL);
 if (!$email) {
  throw new Exception(&#39;Invalid email&#39;);
 }
 $password = filter_iput(INPUT_POST, &#39;password&#39;);
 if (!$password || mb_strlen($password) < 8) {
  throw new Exception(&#39;Password must contain 8+ characters&#39;);
 }
 //创建密码的哈希值
 $passwordHash = password_hash(
  $password,
  PASSWORD_DEFAULT,
  [&#39;cost&#39; => 12]
  );

 if ($passwordHash === false) {
  throw new Exception(&#39;Password hash failed&#39;);
 }

 //创建用户账户，这里是虚构的代码
 $user = new User();
 $user->email = $email;
 $user->password_hash = $passwordHash;
 $user->save();
 header(&#39;HTTP/1.1 302 Redirect&#39;);
 header(&#39;Location: /login.php&#39;);
} catch (Exception $e) {
 header(&#39;HTTP1.1 400 Bad Request&#39;);
 echo $e->getMessage();
}

6). Modify the third value of

password_hash() according to the specific computing power of the machine. Calculating the hash value generally takes 0.1s-0.5s.

7). The hash value of the password is stored in a database column of type

varchar(255).

8).General process of logging in users

POST /login.php HTTP1.1
Content-length: 43
Content-Type: application/x-www-form-urlencoded

email=xiao@hello.wordl&pasword=nihao

session_start();
try {
 $email = filter_input(INPUT_POST, 'email');
 $password = filter_iinput(INPUT_POST, 'password');

 $user = User::findByEmail($email);

 if (password_verify($password, $user->password_hash) === false) {
  throw new Exception(''Invalid password);
 }

 //如果需要的话，重新计算密码的哈希值
 $currentHasAlgorithm = PASSWORD_DEFAULT;
 $currentHashOptions = array('cost' => 15);
 $passwordNeedsRehash = password_needs_rehash(
  $user->password_hash,
  $currentHasAlgorithm,
  $currentHasOptions
 );
 if ($passwordNeedsRehash === true) {
  $user->password_hash = password_hash(
   $password,
   $currentHasAlgorithm,
   $currentHasOptions
  );

  $user->save();
 }

 $_SESSION['user_logged_in'] = 'yes';
 $_SESSION['user_email'] = $email;

 header('HTTP/1.1 302 Redirect');
 header('Location: /user-profile.php');
} catch (Exception) {
 header('HTTP/1.1 401 Unauthorized');
 echo $e->getMessage();
}

9).PHP5.5.0 version The previous password hashing API cannot be used, and it is recommended to use the ircmaxell/password-compat component.

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