Authenticode is a Microsoft technology that uses digital certificates to identify the publisher of an application to ensure the application's integrity and to verify that the software has not been infected by any malware since it was created.
Signature verification is disabled by default because, depending on the speed of your network connection and other factors, the signature verification check may take a noticeably long time. This causes the application to take longer to launch.
Note:
For more information on this topic, see: http://support.microsoft.com/kb/936707.
To enable signature verification: