Jose\Behaviour\EncrypterTrait::determineCEK PHP Method

    private function determineCEK(Object\JWEInterface $jwe, Algorithm\ContentEncryptionAlgorithmInterface $content_encryption_algorithm, $key_management_mode, array &$additional_headers)
    {
        switch ($key_management_mode) {
            case Algorithm\KeyEncryption\KeyEncryptionInterface::MODE_ENCRYPT:
            case Algorithm\KeyEncryption\KeyEncryptionInterface::MODE_WRAP:
                return $this->createCEK($content_encryption_algorithm->getCEKSize());
            case Algorithm\KeyEncryption\KeyEncryptionInterface::MODE_AGREEMENT:
                Assertion::eq(1, $jwe->countRecipients(), 'Unable to encrypt for multiple recipients using key agreement algorithms.');
                $complete_headers = array_merge($jwe->getSharedProtectedHeaders(), $jwe->getSharedHeaders(), $jwe->getRecipient(0)->getHeaders());
                $algorithm = $this->findKeyEncryptionAlgorithm($complete_headers);
                return $algorithm->getAgreementKey($content_encryption_algorithm->getCEKSize(), $content_encryption_algorithm->getAlgorithmName(), $jwe->getRecipient(0)->getRecipientKey(), $complete_headers, $additional_headers);
            case Algorithm\KeyEncryption\KeyEncryptionInterface::MODE_DIRECT:
                Assertion::eq(1, $jwe->countRecipients(), 'Unable to encrypt for multiple recipients using key agreement algorithms.');
                Assertion::eq($jwe->getRecipient(0)->getRecipientKey()->get('kty'), 'oct', 'Wrong key type.');
                Assertion::true($jwe->getRecipient(0)->getRecipientKey()->has('k'), 'The key parameter "k" is missing.');
                return Base64Url::decode($jwe->getRecipient(0)->getRecipientKey()->get('k'));
            default:
                throw new \InvalidArgumentException(sprintf('Unsupported key management mode "%s".', $key_management_mode));
        }
    }