PHP - Is this secure enough for unique session tokens?

Question

I am creating a PHP application and need user authentication to be as secure as possible!

Once the user has logged-in I need to set a cookie (along with other cookies) with a session identifier and this has to be unique.

<?php

// Set default timezone for time() function.
date_default_timezone_set("Europe/London");

$secure_token_length = 16; // 32-Digits Long.

// Generate unique token.
$token = time() . "-" . bin2hex(openssl_random_pseudo_bytes($secure_token_length, $strong));

// Set session identifier.
setcookie("session", $token, 0, "/app/", false, false, true);

?>

As you can see I'm creating a unique token and appending the current UNIX timestamp to ensure that this value is not generated twice, The secure token is stored in a database within a UNIQUE column and the token is not inserted into the database if it is already in use (Using PHP's Do-While function), Any advice on how to make this more secure please comment.

Answer 1

If you want it to be "secure as possible" then please use an established method rather than trying to create your own. For example, let a third-party authenticate for you just like StackOverflow allows you to login with Facebook, Yahoo, etc...

Additionally, PHP has built-in session handling functions which can work with both cookies and databases, OWASP has a guide on how to securely manage your sessions, I don't understand why you're trying to reinvent the wheel here by generating your own session tokens.