Invisible Ink

Scientists at Michigan State University think they have duplicated the formula and technique the East German Stasi used to communicate during the Cold War.

"Agents traced notes onto a piece of paper through a film infused with a chemical solution, much like carbon paper. The writing was revealed by the reader using another special mixture. the scientists explained this week."

You can find the complete article here.

On a separate note, there is a good three-part series on espionage on the Discovery Times channel this month. The series is called CIA Secrets and is broken down in to the stealing, hiding and passing of secrets. Check for programming times on the Discovery Times Web site.