README

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A simple lightweight HMAC generator and checker.

Currently this is used to authenticate applications to other applications.

NOTE

At the moment the Bcrypt adapter is broken on PHP 7. This is due to the changes in the password_hash function. I will be working on a fix for this in v3 which will come out soon.

Installation

To install this use composer by adding

"mardy-git/hmac": "2.*"

to your composer.json file

Usage Example

Generating the HMAC

use Mardy\Hmac\Manager;
use Mardy\Hmac\Adapters\Hash;
use Mardy\Hmac\Exceptions\HmacInvalidAlgorithmException;
use Mardy\Hmac\Exceptions\HmacInvalidArgumentException;

//there are several adapters available 'Bcrypt', 'Hash', 'HashHmac', 'HashPbkdf2'
//you can inject any of them into the manager, they all share the same interface
//With the Bcrypt adapter the num of iteration config is applied to the cost
$manager = new Manager(new Hash);

//you can use any of the Hash algorithms that are available on your environment
$config = [
    'algorithm' => 'sha256',
    'num-first-iterations' => 10,
    'num-second-iterations' => 10,
    'num-final-iterations' => 100,
];

//the private key used in both applications to ensure the hash is the same
$key = 'wul4RekRPOMw4a2A6frifPqnOxDqMXdtRQMt6v6lsCjxEeF9KgdwDCMpcwROTqyPxvs1ftw5qAHjL4Lb';

try {
    $manager->config($config);
} catch (HmacInvalidAlgorithmException $e) {
    //an HmacInvalidAlgorithmException can be caught here
    //"The algorithm ({$algorithm}) selected is not available"
}

//the secure private key that will be stored locally and not sent in the http headers
$manager->key($key);

//the data to be encoded with the hmac, you could use the URI for this
$manager->data('test');

//the current timestamp, this will be compared in the other API to ensure
$manager->time(microtime(true)); //use time() or micortime(true)

//encodes the hmac if all the requirements have been met
try {
    $manager->encode();
} catch (HmacInvalidArgumentException $e) {
    //an HmacInvalidArgumentException can be caught here
    //'The item is not encodable, make sure the key, time and data are set'
}

$hmac = $manager->toArray();

//these values need to be sent in the http headers of the request so they can
//be received by the api and used to authenticated the request
//$hmac = [
//    'data' => 'test-data', //perhaps the uri or other unique string related to the transaction
//    'time' => 1396901689,
//    'hmac' => 'f22081d5fcdc64e3ee78e79d235f67b2d1a54ba24be6da4ac537976d313e07cf119731e76585b9b22f789c6043efe1df133497483f559899db7d2f4398084b08',
//];

Validating the HMAC

use Mardy\Hmac\Manager;
use Mardy\Hmac\Adapters\Hash;
use Mardy\Hmac\Exceptions\HmacInvalidAlgorithmException;

//there are several adapters available 'Bcrypt', 'Hash', 'HashHmac', 'HashPbkdf2'
//you can inject any of them into the manager, they all share the same interface
//With the Bcrypt adapter the num of iteration config is applied to the cost
$manager = new Manager(new Hash);

//you can use any of the Hash algorithms that are available on your environment
$config = [
    'algorithm' => 'sha256',
    'num-first-iterations' => 10,
    'num-second-iterations' => 10,
    'num-final-iterations' => 100,
];

//the private key used in both applications to ensure the hash is the same
$key = 'wul4RekRPOMw4a2A6frifPqnOxDqMXdtRQMt6v6lsCjxEeF9KgdwDCMpcwROTqyPxvs1ftw5qAHjL4Lb';
$ttl = 2;

try {
    $manager->config($config);
} catch (HmacInvalidAlgorithmException $e) {
    //an HmacInvalidAlgorithmException can be caught here
    //"The algorithm ({$algorithm}) selected is not available"
}

//time to live, when checking if the hmac isValid this will ensure
//that the time with have to be with this number of seconds
$manager->ttl($ttl);

//the secure private key that will be stored locally and not sent in the http headers
$manager->key($key);

//get the HMAC values from the $_SERVER/request headers (and make sure you sanitise the values)
$hmac['data'] = filter_var($_SERVER['data'], FILTER_SANITIZE_STRING);
$hmac['time'] = filter_var($_SERVER['time'], FILTER_SANITIZE_STRING);
$hmac['hmac'] = filter_var($_SERVER['hmac'], FILTER_SANITIZE_STRING);

//the data to be encoded with the hmac, you could use the URI for this
$manager->data($hmac['data']);

//the current timestamp, this will be compared in the other API to ensure
$manager->time($hmac['time']);

//to check if the hmac is valid you need to run the isValid() method
//this needs to be executed after the encode method has been ran
if (! $manager->isValid($hmac['hmac'])) {
    http_response_code(401);
    echo 'Invalid credentials';
}

Using with Guzzle

Guzzle is a PHP HTTP client that makes it easy to send HTTP requests and trivial to integrate with web services. https://github.com/guzzle/guzzle

There is now a plugin that will allow integration with guzzle 4+

use GuzzleHttp\Client;
use GuzzleHttp\Event\BeforeEvent;
use Mardy\Hmac\Plugin\HmacHeadersGuzzleEvent;
use Mardy\Hmac\Adapters\Hash;

//Using the HmacHeadersGuzzleEvent class you can automatically inject some headers 
//directly into the guzzle request. This is far more convenient for those of us 
//using dependency injection containers and means we don't have to do it manually 
//each time \o/

$client = new Client;

$client->getEmitter()->on('before', function (BeforeEvent $event) {
    (new HmacHeadersGuzzleEvent(
        new Hash, 
        'wul4RekRPOMw4a2A6frifPqnOxDqMXdtRQMt6v6lsCjxEeF9KgdwDCMpcwROTqyPxvs1ftw5qAHjL4Lb', 
        'test-data', 
        microtime(true)
    ))->onBefore($event);
});

$request = $client->createRequest('GET', 'http://www.google.com');
$client->send($request);