Jose\Algorithm\KeyEncryption\ECDHES::getAgreementKey PHP Method

    public function getAgreementKey($encryption_key_length, $algorithm, JWKInterface $recipient_key, array $complete_header = [], array &$additional_header_values = [])
    {
        if ($recipient_key->has('d')) {
            $this->checkKey($recipient_key, true);
            $private_key = $recipient_key;
            $public_key = $this->getPublicKey($complete_header);
        } else {
            $this->checkKey($recipient_key, false);
            $public_key = $recipient_key;
            switch ($public_key->get('crv')) {
                case 'P-256':
                case 'P-384':
                case 'P-521':
                    $private_key = JWKFactory::createECKey(['crv' => $public_key->get('crv')]);
                    break;
                case 'X25519':
                    $private_key = JWKFactory::createOKPKey(['crv' => 'X25519']);
                    break;
                default:
                    throw new \InvalidArgumentException(sprintf('The curve "%s" is not supported', $public_key->get('crv')));
            }
            $epk = $private_key->toPublic()->getAll();
            $additional_header_values = array_merge($additional_header_values, ['epk' => $epk]);
        }
        Assertion::eq($private_key->get('crv'), $public_key->get('crv'), 'Curves are different');
        $agreed_key = $this->calculateAgreementKey($private_key, $public_key);
        $apu = array_key_exists('apu', $complete_header) ? $complete_header['apu'] : '';
        $apv = array_key_exists('apv', $complete_header) ? $complete_header['apv'] : '';
        return ConcatKDF::generate($agreed_key, $algorithm, $encryption_key_length, $apu, $apv);
    }

 /**
  * {@inheritdoc}
  */
 public function unwrapAgreementKey(JWKInterface $receiver_key, $encrypted_cek, $encryption_key_length, array $complete_header)
 {
     $ecdh_es = new ECDHES();
     $agreement_key = $ecdh_es->getAgreementKey($this->getKeyLength(), $this->getAlgorithmName(), $receiver_key, $complete_header);
     $wrapper = $this->getWrapper();
     return $wrapper->unwrap($agreement_key, $encrypted_cek);
 }