AmazonResolver::sign PHP Method

    function sign($params)
    {
        uksort($params, 'strnatcmp');
        foreach ($params as $key => &$value) {
            $value = $key . '=' . rawurlencode($value);
        }
        // http_build_query uses urlencode rather than rawurlencode
        return base64_encode(hash_hmac('sha256', implode("\n", array('GET', $this->host, $this->path, implode('&', $params))), $this->secret, TRUE));
    }