Facebook: get access token from server side, for users that granted permissions from ios

I have an ios and node js app in which users grant permissions using only client side, and i'm trying not to send the access token to the server for security reasons - someone could intercept that message and use the access token. So I want to get the access token from the server side. Is this possible? I want no user interaction when doing this. For now, i have just got an App access token but i think this is not enough for me. Any suggestions are appreciated.

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