What are some best practices for securely uploading images in PHP, considering potential file manipulation by users?

When allowing users to upload images in PHP, it is crucial to implement security measures to prevent potential file manipulation. One best practice is to validate the file type and ensure it is an image file before allowing the upload. Additionally, consider restricting the file size and renaming the file upon upload to prevent malicious scripts from being executed. 

<?php
// Check if the file is an image
$allowed_extensions = array('jpg', 'jpeg', 'png', 'gif');
$uploaded_file_extension = pathinfo($_FILES['image']['name'], PATHINFO_EXTENSION);

if (!in_array($uploaded_file_extension, $allowed_extensions)) {
    die('Invalid file type. Please upload an image file.');
}

// Check file size
$max_file_size = 2 * 1024 * 1024; // 2MB
if ($_FILES['image']['size'] > $max_file_size) {
    die('File size exceeds limit. Please upload a smaller file.');
}

// Rename file and move to upload directory
$upload_directory = 'uploads/';
$uploaded_file_name = uniqid() . '.' . $uploaded_file_extension;
$uploaded_file_path = $upload_directory . $uploaded_file_name;

if (move_uploaded_file($_FILES['image']['tmp_name'], $uploaded_file_path)) {
    echo 'File uploaded successfully.';
} else {
    echo 'Error uploading file.';
}
?>

Keywords

file upload image manipulation PHP security file validation user input validation

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