$merchantPrivateKeyInstance = Rsa::from($merchantPrivateKeyFilePath, Rsa::KEY_TYPE_PRIVATE);
这一行代码 没法读取私钥   
$pkey = ($isPublic = $type === static::KEY_TYPE_PUBLIC)
    ? openssl_pkey_get_public(self::parse($thing, $type))
    : openssl_pkey_get_private(self::parse($thing));
dd($pkey);
这里返回结果是false