This authentication middleware add WSSE sign functionality to Guzzle Http Client.
composer require ngabor84/guzzle-wsse-middleware
<?php
$wsseMiddleware = new \Guzzle\Http\Middleware\WsseMiddleware($username, $password);
$stack = \GuzzleHttp\HandlerStack::create();
$stack->push($wsseMiddleware);
$client = new \GuzzleHttp\Client(['handler' => $stack]);
// Important: set the auth option to wsse to activate the middleware
$response = $client->get('http://www.8points.de', ['auth' => 'wsse']);