Polo API

PoloTrader.cs

const string ApiKey = "YourAPIKey";
const string ApiSecret = "YourAPISecret";
public async void MyFunc()
        {
            string url = "https://poloniex.com/tradingApi";
            string myParam = "command=returnBalances&nonce=" + nonce();
            string result = await SendPrivateApiRequestAsync(url, myParam);
            //deserialize the result string to your liking
        }
private async Task<string> SendPrivateApiRequestAsync(string privUrl, string myParam)
        {
            using (var client = new HttpClient())
            {
                client.BaseAddress = new Uri(privUrl);
                StringContent myContent = new StringContent(myParam);
                myContent.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
                client.DefaultRequestHeaders.Add("Key", ApiKey);
                client.DefaultRequestHeaders.Add("Sign", genHMAC(myParam));
                var result = await client.PostAsync(privUrl, myContent);
                return await result.Content.ReadAsStringAsync();
            }
        }
private string genHMAC(string message)
        {
            var hmac = new HMACSHA512(Encoding.ASCII.GetBytes(ApiSecret));
            var messagebyte = Encoding.ASCII.GetBytes(message);
            var hashmessage = hmac.ComputeHash(messagebyte);
            var sign = BitConverter.ToString(hashmessage).Replace("-", "").ToLower();
            return sign;
        }

Change line 6 to

string myParam = "command=returnOpenOrders&currencyPair=BTC_XCP&nonce=" + nonce();