How Can PHP's password_hash() and password_verify() Functions Securely Store and Verify Passwords?

Storing and Verifying Passwords Securely with PHP's Password Management Functions

When it comes to handling passwords in web applications, security is paramount. PHP 5.5 introduced the password_hash() and password_verify() functions to assist with this critical task.

Creating a Secure Hash

The password_hash() function generates a secure hash of a given password using an algorithm like BCRYPT. To create a hash, it requires three parameters: the password itself, the hashing algorithm (e.g., PASSWORD_BCRYPT), and an array of options. The options include specifying the cost (a computational factor) and a unique salt (randomly generated data added to the hash to increase its uniqueness).

Storing Password and Salt

Contrary to the initial query, the correct approach is to store both the hash and the salt in the database. This is because password_hash() returns a string containing both elements. So, in a MySQL statement for example:

INSERT INTO users(username, password_hash) VALUES($username, $hashAndSalt);

Password Verification

When a user logs in, the password they enter must be verified against the stored hash. To do this, retrieve the stored hash (which contains both the hash and salt) and pass it to password_verify():

if (password_verify($password, $hashAndSalt)) {
    // Verified
}

Additional Security Measures

Beyond the use of these functions, consider other security measures:

• Use a secure connection to the database (e.g., MySQLi's mysqli_real_connect() with SSL).
• Protect against SQL injection attacks.
• Regularly upgrade PHP and its extensions.
• Implement session management and rate limiting to prevent password brute-force attempts.

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