Just "re-learned" this method for passing info. Obviously obsolete but still interesting to know and still works.  

1) Affix the paper document that you want to copy to a wall. Using a 35mm camera, take a picture of the document leaving approximately 1 inch around the edges.  

2) Cut a 12in x 12in (or larger) size square from light cardboard. In the center of the cardboard cut a 2in x 2in square hole.

3) Develop the film. Take the negative of the photographed document and center it in the hole on the cardboard; affix it in place with tape.

4) Position the cardboard in front of a lamp so that the negative is lit from behind. Using the 35mm camera, take another picture of the negative the width of the cardboard.

5) Develop the film. Find the negative with the document on it. The "picture" of the document will be centered in the negative and will be about half the size of an aspirin or smaller. Cut the minaturized document out of the negative with scissors. The "microdot" can now be hidden anywhere and transported easily (inside a book binding, sewn into a jacket, etc). Should anyone actually find it they will not know what it is unless they've been trained on what to look for.

6) The recipient of the microdot will place it under a microscope and be able to read it word for word.

Anyone else know any old tricks of the trade?


ViCAP

That is an old one!  I recall long ago when somebody actually put the entire Bible on a microdot.

One that I remember, for no reason at all, was putting a flash bulb (I guess you guys remember flashbulbs?) hooked up to go off inside a small film container.  Undeveloped film containing some sort of secret info was placed in the container.  If the wrong person opened the container, the bulb would go off and wipe out the information on the film.

I remember agents putting cameras inside Zerox machines (don’t think they were called that, though) and photographing everything that was copied on the machine.  (I sometimes think about that when I copy my tax return at Staples!!)

There are lots of others.

Is somebody watching TechTV?

I read one Cold War trick where the information was in the line border around the picture on the cover of a magazine.  To the unaided eye it looked like a thin black line, but under extreme magnification- voila!

Why go through the trouble when you can fax the damn thing?