Changing the expiration time of a URL signed with a SecKey

Hi

We are using an external archive server in our system to store documents and data. The content in the HTTP server is accessed through a URL generated by SAP which is signed with a SecKey.

The URL contains an 'expiration time' parameter, once which is passed, the URL is considered invalid and the external archive server rejects the request.

Does anyone know where this expiration time setting is made? (i.e. expire the link 20 mins / 1 hr after the link has been generated) and how can this be changed?

Thanks and Regards

Joy Kaushish