"One-way" transmissive glass - is this possible?

Hi everyone,

I'm struggling with a design project and before I declare it impossible I'd like the input of someone with far more optics knowledge than I have.

Basically what we are trying to create is a screen that an image can be projected onto. The screen should be transparent or reasonably so (some tinting is acceptable). It should function such that when viewed from one direction, the projected image is visible, but when viewed from the other direction the projected image is blocked while still maintaining transparency.

The only way I've thought of to do this is to polarize the light coming out of the projector and put a perpendicular polarizing filter on the back of the screen. However my understanding is that when light hits a diffuse surface the polarization of the light is lost rendering this method ineffective. Am I mistaken?

Is such a thing physically possible? Allowing uncontrolled light transmission in one direction but not in the other? By uncontrolled I mean it is room or stage lighting - not coherent, monochromatic, polarized, or "treated" in any other such fashion.

Thank you for your help.

EDIT: To clarify, the screen should appear transparent from both sides - but the projected image should only be visible on one side. I am fairly sure that a true "one-way window" is physically impossible. Happy to be wrong.