C.I.A. et Première Guerre Mondiale: des documents secrets maintenant accessibles

Près de 100 ans plus tard...

"The documents show top techniques used by spies, generals and diplomats to send secret messages in a diplomatic war that raged long after the guns stopped. The records reveal how invisible ink was used to send word between allies, and spies learned to open letters to read each other's secrets without leaving a trace.

One document suggests this method for passing secret messages: soaking a handkerchief or collar in a mixture of nitrate, soda and starch, then drying the fabric. The chemicals come out when the cloth is placed in water. The liquid becomes invisible ink, that can be loaded into a pen and used to write a message. The recipient develops the writing by applying a second chemical, iodate of potassium.

There's even a document written in French of the German's secret ink formula, showing the French had cracked the enemy's code."

http://www.huffingtonpost.com/2011/04/19/cia-world-war-one-documents-declassified_n_851281.html