[shadowgovt]

In English too, you can retain something to have it, but you can technically also retain to mean "withhold," in the sense that you are keeping it secure or intact and refusing to divulge it.

It's not a very common usage in English though.

[CrazyStat]

Retain in the sense of withhold makes more sense when you're talking about a physical item that can't be duplicated and shared without limit. I don't think I would use it in that sense when talking about data.