Encryption required on https

[turnerape]

We have a website running on https, we are currently loading a third party website's page within an iframe on one of the pages on our website. This third party website is again running on https and uses the referral url as our domain name (it checks if the request has originated from our website and then only loads their page). When we load their page we are passing across some parameters in the iframe src. Going forward we have to send few more parameters (login id etc). Do you suggest to pass these parameters using encryption or since both of the websites are running on https they are secured anyways and hence the encryption is not require?Many thanks Sameer