public string GetAuthorizationHeader(string message)
{
_logger.Debug(string.Format("Start to sign message {0}", message));
var hmacSha1 = new HMACSHA1(Encoding.Default.GetBytes(_configuration.GetClientSecret()));
var sign = Convert.ToBase64String(hmacSha1.ComputeHash(Encoding.Default.GetBytes(message)));
var authorizationSign = string.Format("PP {0}:{1}", _configuration.GetClientKey(), sign);
_logger.Debug(string.Format("End sign message. Generate this authorization header: {0}", authorizationSign));
return authorizationSign;
}