NAMSHI | JOSE

This library provides a lightweight implementation of the JWS (JSON Web Signature) specification.

Prerequisites

This library needs PHP 5.5+ and the library OpenSSL.

It has been tested using PHP5.5 to PHP7.0 and HHVM.

Installation

You can install the library directly from composer / packagist:

"namshi/jose": "6.1.*"

Usage

Using it is pretty straightforward: imagine that you want to offer a service the ability to authenticate a user via a cookie, and the service is built with javascript; what you would need to do is to generate a JWS (after verifying the credentials once), store it as a cookie and then pass it from your JavaScript app everytime you want to authenticate that user.

First, generate the JWS:

<?php

use Namshi\JOSE\SimpleJWS;

if ($username == 'correctUsername' && $pass == 'ok') {
	$user = Db::loadUserByUsername($username);

	$jws  = new SimpleJWS(array(
		'alg' => 'RS256'
	));
	$jws->setPayload(array(
		'uid' => $user->getid(),
	));

    $privateKey = openssl_pkey_get_private("file://path/to/private.key", self::SSL_KEY_PASSPHRASE);
    $jws->sign($privateKey);
    setcookie('identity', $jws->getTokenString());
}

Then your JS app can use the available cookie to execute authenticated calls, without sending passwords or credentials.

Once a request is submitted, you only have to verify that it is a valid call:

<?php

use Namshi\JOSE\SimpleJWS;

$jws        = SimpleJWS::load($_COOKIE['identity']);
$public_key = openssl_pkey_get_public("/path/to/public.key");

// verify that the token is valid and had the same values
// you emitted before while setting it as a cookie
if ($jws->isValid($public_key, 'RS256')) {
	$payload = $jws->getPayload();

	echo sprintf("Hey, my JS app just did an action authenticated as user #%s", $payload['id']);
}

PROTIP: you can omit the second argument of the isValid() method, so jose will try to validate the token with the algorithm specified in the token's header, though this might expose you to some security issues.

For now we recommend to always explicitely set the algorithm you want to use to validate tokens.

PHPSECLIB For RSA Verification

You may find that you need to use this library in an environment where PHP's wrappers for OpenSSL do not work, or OpenSSL simply is not installed. This library uses OpenSSL to encrypt by default, but you can specify that you want to use PHPSecLib for a pure PHP implementation of RSA encryption.

In these cases, simply add the optional 'SecLib' parameter when constructing a JWS:

$jws = new JWS(array('alg' => 'RS256'), 'SecLib');

You can now use the PHPSecLib implementation of RSA signing. If you use a password protected private key, you can still submit the private key to use for signing as a string, as long as you pass the password as the second parameter into the sign method:

$jws->sign(file_get_contents(SSL_KEYS_PATH . "private.key"), 'tests');

You may also load a JWS using the PHPSecLib implementation of RSA verification:

$jws = JWS::load($tokenString, false, $encoder, 'SecLib');

Under the hood

In order to validate the JWS, the signature is first verified with a public key and then we will check whether the token is expired.

To give a JWS a TTL, just use the standard exp value in the payload:

$date    	= new DateTime('tomorrow');
$this->jws  = new SimpleJWS(array('alg' => 'RS256'));
$this->jws->setPayload(array(
	'exp' => $date->format('U'),
));

Unsecure JWSes

You can allow unsecure JWSes by setting the $allowUnsecure flag while loading JWSes:

JWS::load($this->jws->getTokenString(), true);

This allows tokens signed with the 'none' algorithms to go through, which is something you probably don't want to do. Proceed with caution :)

Unsecure JWSes are disabled by default since version 2.2.2. You should not use previous versions other than 2.2.2 as they have a security vulnerability. More info here.

Using a custom encoder

If, for some reason, you need to encode the token in a different way, you can inject any implementation of Namshi\JOSE\Base64\Encoder in a JWS instance. Likewise, JWS::load() accepts such an implementation as a second argument.

Implementation Specifics

The library provides a base JWT Class that implements what is needed just for JSON Web Tokens. The JWS Class then extends the JWT class and adds the implementation for signing and verifying using JSON Web Signatures. The SimpleJWS class extends the base JWS class and adds validation of a TTL and inclusion of automatic claims.

Major Versions

2.x.x to 3.x.x

Introduced the ability to specify an encryption engine. Added support of PHPSecLib to the existing OpenSSL implementation.

3.x.x to 4.x.x - Not Backwards Compatible

Added the ability to set custom properties in the header. Moved automatic inclusion of certain claims into an SimpleJWS class from the base JWS class.

6.x.x - Not Backwards Compatible

6.1.x

• Dropped support for PHP 5.4
• phpseclib 2.0

6.0.x

• Dropped support for PHP 5.3
• Don't escape slashes when generating signin input. This may render tokens generated with earlier versions of Jose incompatible.

Credits

This library has been inspired by the initial work done by @ritou.