Generates a SAS Token for Azure REST Api Calls (Particularly for Service Bus Services like Event Hub & Queues)

SAStoken.cs

/// <summary> 
/// Code  for generating of SAS token for authorization with Service Bus 
/// 
/// This handy function can be found on this helpful blog post:
/// http://developers.de/blogs/damir_dobric/archive/2013/10/17/how-to-create-shared-access-signature-for-service-bus.aspx
/// </summary> 
/// <param name="resourceUri"></param> 
/// <param name="keyName"></param> 
/// <param name="key"></param> 
/// <returns></returns> 
private static string createToken(string resourceUri, string keyName, string key)
{
    TimeSpan sinceEpoch = DateTime.UtcNow - new DateTime(1970, 1, 1);
    var expiry = Convert.ToString((int)sinceEpoch.TotalSeconds + 3600); //EXPIRES in 1h 
    string stringToSign = HttpUtility.UrlEncode(resourceUri) + "\n" + expiry;
    HMACSHA256 hmac = new HMACSHA256(Encoding.UTF8.GetBytes(key));

    var signature = Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(stringToSign)));
    var sasToken = String.Format(CultureInfo.InvariantCulture,
    "SharedAccessSignature sr={0}&sig={1}&se={2}&skn={3}",
        HttpUtility.UrlEncode(resourceUri), HttpUtility.UrlEncode(signature), expiry, keyName);

    return sasToken;
}