Jose\Behaviour\HasKeyChecker::checkOperation PHP Method

    private function checkOperation(JWKInterface $key, $usage)
    {
        $ops = $key->get('key_ops');
        if (!is_array($ops)) {
            $ops = [$ops];
        }
        switch ($usage) {
            case 'verification':
                Assertion::inArray('verify', $ops, 'Key cannot be used to verify a signature');
                return true;
            case 'signature':
                Assertion::inArray('sign', $ops, 'Key cannot be used to sign');
                return true;
            case 'encryption':
                Assertion::true(in_array('encrypt', $ops) || in_array('wrapKey', $ops), 'Key cannot be used to encrypt');
                return true;
            case 'decryption':
                Assertion::true(in_array('decrypt', $ops) || in_array('unwrapKey', $ops), 'Key cannot be used to decrypt');
                return true;
            default:
                throw new \InvalidArgumentException('Unsupported key usage.');
        }
    }