For Remote API; Impersonate or Become User or Logon As Feature

Hello,
I can't search the confluence as an user from my applications. Because there isn't the feature of become user, vs. This blocks the integration processes. My main goal is providing a small dashboard view (specially recent updated section) from our portal application to users with a portlet. I know admin password of the confluence, but i can't get user's passwords from portal server and shouldn't be get, i know user's user name and know that user logged in the portal application with their correct credentials.
So, like many other applications; Become user, impersonate, Logon as feature for remote API would be appreciated.

I hope that i've explained clearly.
Regards,