Publish article for Apple news API using C# - (401) Unauthorized

Question

I am working on posting article using Apple news API.

I created new account and also created new channel.

Below is the code snippet which I am using.

        string channel_id = "{Channel_Id}";
        string api_key_id = "{Key_Id}";
        string api_key_secret = "{Secret}";
        var path = "https://news-api.apple.com/channels/" + channel_id + "/articles";

        var httpWebRequest = (HttpWebRequest)WebRequest.Create(path);
        httpWebRequest.ContentType = "multipart/form-data";
        httpWebRequest.Method = "POST";
        httpWebRequest.Accept = "application/json";
        httpWebRequest.Host = "news-api.apple.com";
        httpWebRequest.UseDefaultCredentials = true;
        httpWebRequest.PreAuthenticate = true;

        httpWebRequest.ProtocolVersion = HttpVersion.Version11;
        httpWebRequest.KeepAlive = true;
        string appleDate = String.Format("{0}Z", DateTime.UtcNow.ToString("s"));
        string credentials = String.Format("{0}:{1}", "Content-Disposition", "form-data; ");
        credentials += String.Format("{0}:{1}", "filename", "article.json; ");
        credentials += String.Format("{0}:{1}", "name", "article.json; ");

        credentials += String.Format("{0}","HHMAC; ");
        credentials += String.Format("{0}={1}", "key", api_key_id + "; ");

        string decodedSecret = base64Decode(api_key_secret);
        string canonical_request = path + "POST" + appleDate ;
        string hash = Class1.HmacSha256Digest(canonical_request, decodedSecret);
        string Encodedhash = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(hash));

        credentials += String.Format("{0}={1}", "signature", Encodedhash + "; ");
        credentials += String.Format("{0}={1}", "date", appleDate + "; ");


        httpWebRequest.Headers.Add("Authorization", credentials);

        using (StreamReader r = new StreamReader(Directory.GetCurrentDirectory() + ("/article.json")))
        {
            string json = r.ReadToEnd();
            dynamic jsonObj = JsonConvert.DeserializeObject(json);

            ASCIIEncoding encoding = new ASCIIEncoding();
            Byte[] bytes = encoding.GetBytes(json);
            Stream newStream = httpWebRequest.GetRequestStream();
            newStream.Write(bytes, 0, bytes.Length);
            newStream.Close();
        }
        var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
        using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
        {
            var result = streamReader.ReadToEnd();
        }

Here is base64Decode function

public static string base64Decode(string data)
        {
            var base64EncodedBytes = System.Convert.FromBase64String(data);
            return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
        }

Here is class to convert Sha256Digest

public static class Class1
    {
        public static string HmacSha256Digest(this string message, string secret)
        {
            ASCIIEncoding encoding = new ASCIIEncoding();
            byte[] keyBytes = encoding.GetBytes(secret);
            byte[] messageBytes = encoding.GetBytes(message);
            System.Security.Cryptography.HMACSHA256 cryptographer = new System.Security.Cryptography.HMACSHA256(keyBytes);

            byte[] bytes = cryptographer.ComputeHash(messageBytes);

            return BitConverter.ToString(bytes).Replace("-", "").ToLower();
        }
    }

Whenever I am trying to post the API I am getting below error message:

"'The remote server returned an error: (401) Unauthorized".

When I am trying to post the API request using Postman then I am getting below error message:

{
    "errors": [
        {
            "code": "WRONG_SIGNATURE"
        }
    ]
}

Is there anything incorrect to generate Signature ?

I researched few articles but unable to find any solution.

Please guide me to find out the solution on this.

I have tried the same thing for creating a report and I have followed the following link for the python code. https://developer.apple.com/documentation/apple_news/apple_news_api/about_the_news_security_model But I am getting the exact same error. I would love to know the solution as well. — Rafiul Sabbir, Aug 08 '18 at 10:15

score 1 · Answer 1 · answered Aug 17 '18 at 10:59

I don't have time to go through the entirety of your code and suggest you start with a simpler Channel Data request before attempting to POST json, but a potential couple of bits I noticed:

You use ASCII encoding where you should be using UTF8 throughout.
You strip hyphens from the Base64 but Apple only strips returns and whitespace
The cannonical request should be written: "POST[url][date][contentType]" where url = "https://news-api.apple.com/channels/[channelID]/articles", date is in the format "yyyy-MM-dd'T'HH:mm:ss'Z'" and content-type = "multipart/form-data; boundary=[boundary]" where boundary is any string used to divide the content.

See also my tips on using Python, most importantly ensure you are using the path to a folder containing article.json (not the path to a file). And finally here is my own translation of the Python into Swift.

Publish article for Apple news API using C# - (401) Unauthorized

1 Answers1