I was reading GitLab’s documentation (see link) on how to write to a repository from within the CI pipeline and noticed something: The described Docker executor is able to authenticate e.g. against the Git repository with only a private SSH key, being told absolutely nothing about the user’s name it is associated with.
If I’m correct, that would mean that technically, I could authenticate to an SSH server without supplying my name if I use a private key?
I know that when I don’t supply a user explicitly like ssh user@server or via .ssh/config, the active environment’s user is used automatically, that’s not what I’m asking.
The public key contains a user name/email address string, I’m aware, is the same information also encoded into the private key as well? If yes, I don’t see the need to hand that info to an SSH call. If no, how does the SSH server know which public key it’s supposed to use to challenge my private key ownership? It would have to iterate over all saved keys, which sounds rather inefficient to me and potentially unsafe (timing attacks etc.).
I hope I’m somewhat clear, for some reason I find it really hard to phrase this question.
I only have experience with Bitbucket, and absolutely none if this may be applicable to you, but we have to generate a key with certain parameters (a minimum) for them to work, and the public key has to be input into a field on your account. So while you do not need to “provide” a username to perform git commands, it is set up in your account as your private key. The command to gen the key is: ssh-keygen -t rsa -m PEM -b 4096 -C “[email protected]”
Once you put your public key into your bitbucket account, using that key will mark all changes you make to you. Is this what you are talking about or am I just off in left field?