From Halopedia, the Halo wiki
SERVICE NUMBER: CTN 0452-9
Not a lot on file here, so it looks like Halsey’s done a decent job of covering her tracks (and I can’t blame her, given the AI’s actual origin).
I know full well that neither of you get along and I’m definitely not claiming that she shouldn’t be held accountable for some of the stunts she’s pulled. Reality is that we need her for this op. That’s why she’s been here for the last three decades.
As indicated in the previous conversation, she’s splitting Cortana into two separate programs in order to juggle the Visegrád findings with this operation, and she’s assured me that the AI is fully functional, well within her capacity for this mission. I believe her and I’m hoping that you can believe me.