[Amazon][API][PHP] Amazon 新 API (2009.08.15) 対応

$URL =	'http://webservices.amazon.co.jp/onca/xml' .
	'?Service=AWSECommerceService' .
	'&SubscriptionId=' . $subscription_id .
	'&AssociateTag=' . $associate_id .
	'&Operation=ItemSearch' .
	'&SearchIndex=' . $search_index .
	'&ResponseGroup=Medium' .
	'&Keywords=' . $keywords .
	'&Version=2005-07-27' .
	'&Timestamp=' . urlencode(gmdate('Y-m-d\TH:i:s\Z'));

$parsed_url = parse_url($URL);

$parsed_query = explode('&', $parsed_url['query']);
sort($parsed_query);
$query = implode('&', $parsed_query);

$signature =
	"GET\n" .
	$parsed_url['host'] . "\n" .
	$parsed_url['path'] . "\n" .
	$query;
$signature = base64_encode(hash_hmac('sha256', $signature, $secret_key, true));

$URL =	$parsed_url['scheme'] . '://' .
	$parsed_url['host'] .
	$parsed_url['path'] .
	'?' . $query .
	'&Signature=' . str_replace('%7E', '~', rawurlencode($signature));