登录服务器时出现C＃Base-64错误

Question

我正在测试我自己的方法，我昨晚为我正在处理的程序登录数据库，一切都很好。当我今天早上尝试登录数据库时出现Base-64错误。这是完整的错误。

The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters.

在我将程序投入生产之前，我需要修复此错误，但我无法弄清楚导致它的原因。这是登录代码（我排除了真实的服务器地址和真正的加密密钥以确保安全，但它不应该有所作为。）

private void login_Click(object sender, EventArgs e)
        {
            try
            {
                WebRequest request_user = WebRequest.Create("server address here");
                WebResponse response_user = request_user.GetResponse();
                StreamReader sr_user = new StreamReader(response_user.GetResponseStream());
                string user = RC4.Decrypt("encryption key here", sr_user.ReadToEnd());
                //show("Client: " + username.Text + "\nServer: " + user);

                WebRequest request_pass = WebRequest.Create("server address here");
                WebResponse response_pass = request_pass.GetResponse();
                StreamReader sr_pass = new StreamReader(response_pass.GetResponseStream());
                string pass = RC4.Decrypt("encryption key here", sr_pass.ReadToEnd());
                //show("Client: " + password.Text + "\nServer: " + pass);

                WebRequest request_key1 = WebRequest.Create("server address here");
                WebResponse response_key1 = request_key1.GetResponse();
                StreamReader sr_key1 = new StreamReader(response_key1.GetResponseStream());
                string key1 = RC4.Decrypt("encryption key here", sr_key1.ReadToEnd());
                //show("Client: " + RC4.Decrypt("encryption key here", AuthKey1) + "\nServer: " + key1);

                WebRequest request_key2 = WebRequest.Create("server address here");
                WebResponse response_key2 = request_key2.GetResponse();
                StreamReader sr_key2 = new StreamReader(response_key2.GetResponseStream());
                string key2 = RC4.Decrypt("encryption key here", sr_key2.ReadToEnd());
                //show("Client: " + RC4.Decrypt("encryption key here", AuthKey2) + "\nServer: " + key2);

                WebRequest request_ipv4 = WebRequest.Create("server address here");
                WebResponse response_ipv4 = request_ipv4.GetResponse();
                StreamReader sr_ipv4 = new StreamReader(response_ipv4.GetResponseStream());
                string ipv4 = sr_ipv4.ReadToEnd();
                //show("Client: " + IPAddress + "\nServer: " + ipv4);

                if (user.Contains(username.Text) && pass.Contains(password.Text) && key1.Contains(RC4.Decrypt("encryption key here", AuthKey1)) && key2.Contains(RC4.Decrypt("encryption key here", AuthKey2)) && ipv4.Contains(IPAddress))
                {
                    WebRequest request_tu = WebRequest.Create("server address here");
                    WebResponse response_tu = request_tu.GetResponse();
                    StreamReader sr_tu = new StreamReader(response_tu.GetResponseStream());
                    string tu = sr_tu.ReadToEnd();
                    show("Successfully logged into the Grand Theft Rape Server!\nCurrent TU: " + tu);
                }
                else
                {
                    show("Username and/or Password incorrect!");
                }
            }
            catch (Exception ex)
            {
                show(ex.Message);
            }
        }