Create Auth Tokens with PHP

By  on  

Working with OAuth and similar authentication protocols requires the use of temporary tokens which represent unique handshakes between multiple web services.  These tokens must be unique, securely stored, and the longer, the better.

Since I've been out of the PHP game for a while, I was researching how to create such tokens without additional libraries.  The following snippet does the trick:

// bin2hex(random_bytes($length))
$token = bin2hex(random_bytes(64));

/*
  Examples:

  39e9289a5b8328ecc4286da11076748716c41ec7fb94839a689f7dac5cdf5ba8bdc9a9acdc95b95245f80a00d58c9575c203ceb541507cce40dd5a96e9399f4a
  1c46538c712e9b5bf0fe43d692147004f617b494d004e29daaf33e4528f253db5d911a690856f0b77cfa98103c8231bffff869f179125d17d28e52bfadb9f205
  ...
*/

If you aren't using PHP7 or above, you can fallback to the following:

$token = bin2hex(openssl_random_pseudo_bytes(64));

Having the backing of OpenSSL for token generation gives confidence that the token will be unique.  Of course you can also do a storage check to ensure the token isn't already in use, but if you use a length of 64 or larger, the chances you repeat a token are incredibly slim!

Recent Features

  • By
    Regular Expressions for the Rest of Us

    Sooner or later you'll run across a regular expression. With their cryptic syntax, confusing documentation and massive learning curve, most developers settle for copying and pasting them from StackOverflow and hoping they work. But what if you could decode regular expressions and harness their power? In...

  • By
    Create a CSS Cube

    CSS cubes really showcase what CSS has become over the years, evolving from simple color and dimension directives to a language capable of creating deep, creative visuals.  Add animation and you've got something really neat.  Unfortunately each CSS cube tutorial I've read is a bit...

Incredible Demos

Discussion

  1. Thanks for sharing!

  2. Valtteri

    I’ve used this, because it’s produces a shorter string:

    $token = base64_encode(random_bytes(64));
    
    // Example:
    // yak91pYnDWkaDPEjGAOgGcdTA4ybHF+R+5KVcvgfuoAJz3QMmaxJfBYIkKT9zpSDRE6jfHMW9jahsw1b/aMXtw==
    

    Usually I replace + and / with - and _, so it doesn’t need encoding anywhere:

    $token = strtr($token, '+/', '-_');
    
  3. A word of advice: don’t use openssl_random_pseudo_bytes() as a fallback for random_bytes() in PHP 5.x, use the random_compat library instead: https://github.com/paragonie/random_compat.

  4. Thanks for the trick. How’s the random_compat compared to openssl_random_pseudo_bytes()

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!