public UploadSignature(string response)
{
this._signature = response;
//parse actual signature
_toJson = JsonConvert.SerializeXmlNode(toXmlDocument().SelectSingleNode("//vzaar-api"), Newtonsoft.Json.Formatting.None, true);
var jo = (JObject)JsonConvert.DeserializeObject(_toJson);
guid = (string)jo["guid"];
bucket = (string)jo["bucket"];
expirationDate = DateTime.Parse((string)jo["expirationdate"].ToString());
signature = (string)jo["signature"];
acl = (string)jo["acl"];
key = (string)jo["key"];
accessKeyId = (string)jo["accesskeyid"];
policy = (string)jo["policy"];
https = (bool)jo["https"];
uplodHostname = (string)jo["upload_hostname"];
chunkSize = (string)jo["chunk_size"];
}