How does my iPhone know which PC I've plugged it into then? Even when iTunes isn't installed (so no "Apple Mobile Device" drivers) it seems to remember my priva

How does my iPhone know which PC I've plugged it into then? Even when iTunes isn't installed (so no "Apple Mobile Device" drivers) it seems to remember my privacy preferences on a per-host basis. I'll concede that may be a feature of the allocation protocol running on top of USB (PictBridge?) but that still means that mutual identification over USB is still possible. I'm pretty sure it's in the USB HID spec that the Xbox controllers implement.