PHP data filtering: effectively prevent password guessing

PHP Data Filtering: Effectively Prevent Password Guessing

In today's network environment, security is crucial. As developers, we must protect user privacy and data security at all times. Especially when it comes to user passwords, password guessing attacks are a very common attack method. In order to prevent password guessing attacks, we need to do a good job of data filtering. This article will introduce how to use PHP to effectively prevent password guessing attacks and provide some practical code examples.

1. Principle of password guessing attack

Password guessing attack is when the attacker guesses the user's password by trying different password combinations. Attackers would use automated tools to enumerate all possible passwords until they find the correct one. This attack method can quickly obtain user passwords, so it is very dangerous. To prevent password guessing attacks, we can use the following methods.

2. Password strength verification

The first method is to prevent password guessing attacks by verifying the strength of the password. We can define some password strength rules, for example, the password length must be within a specific range and must contain letters, numbers, special characters, etc. When a user registers or changes their password, we can use PHP's regular expression function preg_match() to check whether the password complies with our strength rules. The following is a sample code:

$password = $_POST['password'];

$pattern = '/^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#$%^&*])[a-zA-Z0-9!@#$%^&*]{8,}$/';

if(preg_match($pattern, $password)){
   // 密码符合强度规则
   // 将密码存储到数据库或进行其他操作
} else {
   // 密码不符合强度规则
   // 给用户提示错误信息
}

In the above code, we use a regular expression to define password strength rules. This regular expression requires that the password be at least 8 characters long and must contain at least one lowercase letter, one uppercase letter, one number, and one special character. If the user's password meets this strength rule, then we can continue to store the password or perform other operations. Otherwise, we give the user an error message.

3. Limitation of login times

The second method is to prevent password guessing attacks by limiting the number of user logins. We can set a limit on the number of failed logins, for example, only allow users to fail to log in 3 times within a certain time range. If a user fails to log in continuously for a limited number of times, we can temporarily lock the user account. The following is a sample code:

$username = $_POST['username'];
$password = $_POST['password'];

// 获取用户登录失败次数和上次登录失败的时间
$getFailedLoginInfo = "SELECT failed_login_count, last_failed_login FROM users WHERE username='$username'";
// 执行查询

$failedLoginCount = $getFailedLoginInfo['failed_login_count'];
$lastFailedLogin = $getFailedLoginInfo['last_failed_login'];

if($failedLoginCount >= 3 && time() - $lastFailedLogin < 3600){
   // 用户登录失败次数已达到限制，并且上次登录失败的时间小于1小时
   // 暂时锁定用户账号
   // 给用户提示错误信息
} else {
   // 用户登录失败次数未达到限制或上次登录失败的时间超过1小时
   // 进行密码验证和其他操作
}

In the above code, we first obtain the number of failed user logins and the time of the last failed login from the database. If the number of user failed logins has reached the limit and the last failed login is less than 1 hour, we can temporarily lock the user account. Otherwise, we can perform password verification and other operations.

4. Verification code verification

The third method is to use verification code verification to prevent password guessing attacks. We can require users to enter a verification code before logging in or performing sensitive operations. The verification code can be an image or a string of text, and the user needs to enter the verification code correctly to continue. The following is a sample code:

session_start();

if($_POST['captcha'] != $_SESSION['captcha']){
   // 验证码不正确
   // 给用户提示错误信息
} else {
   // 验证码正确
   // 进行密码验证和其他操作
}

In the above code, we first start the session and save the verification code in the session variable. When the user submits the login form, we compare the verification code entered by the user with the verification code saved in the session. If the verification code is incorrect, then we give the user an error message. Otherwise, we can perform password verification and other operations.

Summary

In this article, we introduced three methods to effectively prevent password guessing attacks: password strength verification, login limit and verification code verification. By using these methods appropriately, we can greatly improve the security of user passwords and protect user privacy and data security. In actual development, we can choose appropriate methods to prevent password guessing attacks as needed.

However, it should be noted that these methods only increase the difficulty of password guessing attacks and cannot completely eliminate password guessing attacks. Therefore, we also need to take additional security measures, such as using HTTPS protocol to transfer data, regularly updating password hashes, etc. Through the comprehensive application of multiple protective measures, we can better protect users' privacy and data security.

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