string dateTimeString = DateTime.UtcNow.ToString("R", CultureInfo.InvariantCulture);
string hashString = ComputeHash(strTenant + dateTimeString, key);

##</code><code>##

my $dateTimeString = strftime('%a, %e %b %Y %T',localtime);
my $data = $strTenant.$dateTimeString.' UTC';
$digest = hmac_md5($data, $pkey);