2-way mirror?

I have a project in which I need to build a box made out of two way mirrors, in other words I need the contents of the box to be caught in the boxes inner reflective surface, but the exterior of the box to be transparent glass with no reflection of the box’s exterior, I’ve figured out a way to cheat it with compositing, but if anyone has any idea how to do it simply with materials or material nodes I’d love to hear from you!