How to prevent PHP form data from being tampered with?

How to prevent PHP form data from being tampered with?

When using PHP to develop a website, forms are a frequently used interaction method. However, many times we face a serious security issue, that is, the risk of form data being tampered with. Hackers may perform bad operations by tampering with form data, such as maliciously submitting data, modifying other people's information, etc. In order to prevent this from happening, we need to add some security measures to PHP. The following will introduce some common methods to prevent PHP form data from being tampered with.

1. Verify the source of the form
   When the client submits form data to the server, we can ensure the legitimacy of the data by verifying the source of the request. The most common way is to use Session verification or Token verification.

The principle of Session verification is that when a user accesses the website, the server assigns him a unique Session ID and saves the ID on the server. When the user submits the form, the server will compare whether the Session ID submitted in the form is consistent with the Session ID saved by the server. If they are inconsistent, the data source may be illegal.

Sample code:

session_start();
if(isset($_SESSION['token']) && $_POST['token'] == $_SESSION['token']){
    // 验证通过，处理表单数据
}else{
    // 验证失败，提示错误信息
}

The principle of Token verification is to embed a randomly generated Token in the form, and send the Token to the server when the form is submitted. After the server receives it, it verifies whether the Token in the form is consistent with the Token stored in the server. If they are consistent, the verification passes.

Sample code:

session_start();
if(isset($_POST['token']) && $_POST['token'] == $_SESSION['token']){
    // 验证通过，处理表单数据
}else{
    // 验证失败，提示错误信息
}

2. Using HTTPS protocol
   Using HTTPS protocol can protect the secure transmission of data through data encryption. The HTTPS protocol uses SSL (Secure Socket Layer) or TLS (Transport Layer Security) to encrypt communication content. In this way, even if a hacker intercepts the transmitted data, he cannot decrypt the content, thus ensuring the integrity and security of the data.

Sample code:

if($_SERVER['HTTPS'] != 'on'){
    header("Location: https://" . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI']);
    exit();
}

3. Verify the legality of form data
   In addition to verifying the source of the form, we also need to verify the input data in the form Legality verification to prevent hackers from exploiting malicious data submissions. For example, you can perform format verification on the mobile phone number, email address, password, etc. in the form.

Sample code:

if(!preg_match("/^1[3456789]d{9}$/", $_POST['phone'])){
    // 手机号格式不正确，提示错误信息
}

if(!filter_var($_POST['email'], FILTER_VALIDATE_EMAIL)){
    // 邮箱格式不正确，提示错误信息
}

4. Encrypted storage of sensitive data
   When the form contains the user's sensitive information, such as passwords, ID numbers, etc., we should The data is encrypted before being stored in the database. In this way, even if a hacker obtains the data in the database, he will not be able to obtain the plain text sensitive information.

Sample code:

$password = md5($_POST['password']); // 使用MD5加密密码
// 存储到数据库

Summary:
By verifying the source of form data, using the HTTPS protocol, verifying the validity of the data, and encrypting and storing sensitive data, we can Effectively prevent the risk of PHP form data being tampered with. In development, we should always put security first to ensure that user data is not attacked by hackers.

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