How to generate signature for Oauth1.0 for here api c#

Question

I want to send access token request for bearer token to here api.(https://developer.here.com/tutorials/how-to-authenticate-with-here-oauth/) They showed example using node. But I tried the same way in c#. But I got 400 bad request. My code is as following:

var url = "https://account.api.here.com/oauth2/token";

            String id = "key id";
            String secret = "key secret";

            var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
            httpWebRequest.Method = "POST";

            var timeStamp = ((int)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds).ToString();
            var nonce = Convert.ToBase64String(Encoding.UTF8.GetBytes(timeStamp));

            var signatureBaseString = Escape(httpWebRequest.Method.ToUpper()) + "&";
            signatureBaseString += url.ToLower() + "&";
            signatureBaseString +=
                "oauth_consumer_key=" + id + "&" +
                "oauth_nonce=" + nonce + "&" +
                "oauth_signature_method=" + "HMAC-SHA1" + "&" +
                "oauth_timestamp=" + timeStamp + "&" +
                "oauth_version=" + "1.0";

            var key = secret;

            var signatureEncoding = new ASCIIEncoding();
            var keyBytes = signatureEncoding.GetBytes(key);
            var signatureBaseBytes = signatureEncoding.GetBytes(signatureBaseString);
            string signatureString;
            using (var hmacsha1 = new HMACSHA1(keyBytes))
            {
                var hashBytes = hmacsha1.ComputeHash(signatureBaseBytes);
                signatureString = Convert.ToBase64String(hashBytes);
            }
            string SimpleQuote(string s) => '"' + s + '"';

            var header =
            "Content-Type=application/x-www-form-urlencoded" + "," +
            "Authorization=OAuth" + "," +
            "oauth_consumer_key=" + SimpleQuote(id) + "," +
            "oauth_nonce=" + SimpleQuote(nonce) + "," +
            "oauth_signature_method=" + SimpleQuote("HMAC-SHA1") + "," +
            "oauth_timestamp=" + SimpleQuote(timeStamp) + "," +
            "oauth_version=" + SimpleQuote("1.0") + "," +
            "oauth_signature= " + SimpleQuote(signatureString);

            httpWebRequest.Headers.Add(HttpRequestHeader.Authorization, header);

            string postData = "grant_type=client_credentials";
            ASCIIEncoding encoding = new ASCIIEncoding();
            byte[] byte1 = encoding.GetBytes(postData);

            httpWebRequest.ContentLength = byte1.Length;

            var newStream = httpWebRequest.GetRequestStream(); // get a ref to the request body so it can be modified
            newStream.Write(byte1, 0, byte1.Length);
            newStream.Close();

            var response = httpWebRequest.GetResponse();

May be I am generating the signature in wrong way. But I only have key id and secret and I managed to implement this far. Please help me pointing the mistake I made.

Answer 1

Would you please have a look below article? Getting (401) UnAuthorized error on some requests not all, but most Try to use different lib such as HttpClient or RestClient.