如何用 C# 编写 Python b“mystring”

短篇小说：我试过了

Encoding.ASCII.GetBytes("mystring") 

但它似乎不起作用...

说来话长：我正在尝试调用一个 API，并且我有这个 python 示例代码可用：

userpass = username + ":" + password
encoded_credentials = b"Basic " + base64.b64encode(userpass.encode('ascii'))
headers = {'Version': '2.0', 'Accept': 'application/json', 'Authorization': encoded_credentials}
url = 'https://' + server_ip + '/api/help/capabilities'
request = urllib.request.Request(url, headers=headers)
response = urllib.request.urlopen(request)

我制作的 c# 代码是：

string userpass = username + ":" + password;
byte[] encodedbytes = System.Text.ASCIIEncoding.ASCII.GetBytes(userpass);
var encoded_credentials = Encoding.ASCII.GetBytes("Basic ") + Convert.ToBase64String(encodedbytes);
var request = (HttpWebRequest)WebRequest.Create("https://" + server_ip + "/api/help/capabilities");
request.Method = "GET";
request.ContentType = "application/json";
request.Headers.Add("Authorization", encoded_credentials);
var response = (HttpWebResponse)request.GetResponse()

我得到的结果是 401，未经授权...所以我相信我在用户名密码的编码过程中错过了一些东西！

var encoded_credentials = "Basic " + Convert.ToBase64String(Encoding.UTF8.GetBytes(userpass));

"mystring"