Pulling private bitbucket repos

Our php (laravel) apps pull (via composer) several other bitbucket private repos. I can’t seem to sort out how to give them the correct keys to be able to access them. I can’t see where to grab circleCi’s ssh keys to put in as deployment keys.

You have to give CircleCI a SSh key to use: https://circleci.com/docs/github-security-ssh-keys/#security

They doc mentions GitHub but the concept is the same for Bitbucket.