/**
* Get Client Assertion
* Generates base64 Url safe client assertion
* @param string $get_token_url
* @return string
*/
public function get($getTokenUrl)
{
$clientAssertionHeader = array('alg' => $this->alg, 'x5t' => Office365::getThumbprint());
$now = $this->now();
$clientAssertionPayload = array('sub' => Office365::getClientId(), 'iss' => Office365::getClientId(), 'jti' => self::nonce(), 'exp' => $this->tenMinutesFromNow($now), 'nbf' => $now, 'aud' => $getTokenUrl);
$assertionBlob = $this->getBlob($clientAssertionHeader, $clientAssertionPayload);
$signature = $this->getSignature($assertionBlob);
$clientAssertion = $assertionBlob . '.' . $signature;
return $clientAssertion;
}
