验证服务端数据 ``rsa`` 签名

def rsa_check_base64_sign_str(self, cipher, sign, b64=True):
        """
            验证服务端数据 ``rsa`` 签名

        """
        with open(self.key_file) as fp:
            key_ = RSA.importKey(fp.read())
            v = pkcs.new(key_)
            sign = base64.b64decode(sign) if b64 else sign
            cipher = helper.to_bytes(cipher)
            # if hasattr(cipher, 'encode'):
            #     cipher = cipher.encode('utf-8')
            return v.verify(SHA.new(cipher), sign)