Calculating HMACSHA256 using c# to match payment provider example

Question

For a payment provider, I need to calculate a hash-based message authentication code, using HMAC-SHA256. That is causing me quite a bit of trouble.

The payment provi

Answer 1

Thanks you saved my time.

request.Method = "GET";
string signature = "";
string strtime = DateTime.UtcNow.ToString("yyyy-MM-ddTHH\\:mm\\:ssZ");

string secret = "xxxx";

string message = "sellerid:email:" + strtime; 

var encoding = new System.Text.ASCIIEncoding(); 

byte[] keyByte = encoding.GetBytes(secret);

byte[] messageBytes = encoding.GetBytes(message);
using (var hmacsha256 = new HMACSHA256(keyByte))
{
var hash = new HMACSHA256(keyByte);
byte[] signature1 = hash.ComputeHash(messageBytes);
signature = BitConverter.ToString(signature1).Replace("-", "").ToLower();
}

request.Headers.Add("authorization", "HMAC-SHA256" + " " + 
"emailaddress=xxx@xx.com,timestamp=" + strtime + ",signature=" + signature);
HttpWebResponse response = request.GetResponse() as HttpWebResponse;