What are the best practices for securely handling user input like usernames and passwords in PHP scripts to prevent security vulnerabilities?

When handling user input like usernames and passwords in PHP scripts, it is essential to sanitize and validate the input to prevent security vulnerabilities such as SQL injection and cross-site scripting attacks. One way to do this is by using prepared statements with parameterized queries to interact with the database securely. Additionally, storing passwords securely by hashing them using functions like password_hash() and verifying them with password_verify() is crucial for protecting user data. 

// Example of securely handling user input for username and password

// Sanitize and validate username input
$username = filter_var($_POST['username'], FILTER_SANITIZE_STRING);

// Hash and store password securely
$password = password_hash($_POST['password'], PASSWORD_DEFAULT);

// Verify password
if (password_verify($_POST['password'], $password)) {
    // Password is correct
} else {
    // Password is incorrect
}

Keywords

SQL injection password hashing prepared statements input validation cross-site scripting

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