message = 'BITSTAMP ' + api_key + \
    'POST' + \
    'www.bitstamp.net' + \
    '/api/v2/user_transactions/' + \
    '' + \
    content_type + \
    nonce + \
    timestamp + \
    'v2' + \
    payload_string

##</code><code>##

my $msg = $apiKey.'POST'.$urlcb.$urlpath.$ContentType.$nonce.$timestamp.$API_Version.$Query, $apiSecret;
print "Computing signature over [$msg]\n";
my $signature = hmac_sha256_hex($msg, $apiSecret);