获取无效的签名机架空间云文件

Question

I am trying to upload files to rackspace cloudfiles but getting invalid signature.

i have tried creating signature like

          $max_file_count = 25;
          $expires = (time() + 36000);
          $key = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx';
          $hmac_body = sprintf("%s
%s
%s
%s
%s", $path, $redirect, $max_file_size, $max_file_count, $expires);
          $signature = hash_hmac('sha1', $hmac_body, $key);

Need help please.