Microdot
From Wikipedia, the free encyclopedia
- This article is about reduced size text or photographic images. For other uses, see Microdot (disambiguation).
A microdot is a text or image shrunk to prevent viewing by unintended recipients. A microdot is frequently shrunk to the size and shape of a typographical dot, such as a period or the tittle of a lowercase i or j. It is a technique of steganography.
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[edit] History
In 1870 during the Franco-Prussian War, Paris was under siege. Messages were sent by carrier pigeon. A Parisian photographer named Dagron used a microfilm technique to enable each pigeon to carry a high volume of messages.[1] However, the images were not as small as microdots.[2]
A microdot technique was used with steganographic purposes in Germany between World War I and World War II. It was later used by many countries to pass messages through insecure postal channels. Later microdot techniques used film with aniline dye, rather than silver halide layers, and were even harder for counter-espionage postal inspectors to find. A Professor Zapp in Germany is claimed to have been the inventor of the technique, and a WWII spy kit for microdot production was sometimes called a Zapp outfit.
After the erection of the Berlin Wall, special cameras were used to generate microdots which were then adhered to letters and sent via normal means. Owing to the extremely small size of the microdot, these messages often went unnoticed by inspectors and information could then be read by the intended recipient using a microscope.
British mail censors sometimes referred to microdots as 'duff' since they were distributed here and there throughout letters rather like raisins in the British steamed suet pudding called plum duff.
[edit] Modern usage
[edit] Microdot Identification
Microdot identification is a process where tiny laser discs etched with the vehicle's VIN number are sprayed onto the car's major mechanical parts and under body areas. The technology was developed in Australia in 2001.
Since then, car manufacturers began using microdot identification. About 10,000 identifying numbers are sprayed on with a clear adhesive that cannot be seen by the human eye. This process, while quick and cost effective, deters car thieves who would have otherwise been able to rebirth vehicles as well as sell stolen vehicle parts as legitimate ones. Estimates of the cost to manufacturers of implementing the microdot technology vary between AUD $100 (USD $75)[3] and AUD $150[4] per vehicle. This cost is expected to drop as volume increases.
[edit] List of currently known manufacturers utilising microdot technology
- Audi
- BMW
- Ford Performance Vehicles
- Holden Special Vehicles
- Mitsubishi Ralliart
- Porsche
- Subaru
- Toyota
- Nissan
[edit] Trivia
A microdot was depicted in the the motion picture Mission Impossible 3. In the movie, the microdot was hidden at the back of postage stamp.
[edit] See also
[edit] References
- White, William. The Microdot: History and Application. Williamstown, NJ: Phillips Publications, 1992.
- ^ Kipper, Gregory. Investigator's Guide to Steganography. Boca Raton: Auerbach Publications, 2003.
- ^ Hayhurst, J.D. The Pigeon Post into Paris 1870-1871. Privately published, 1970.
- ^ Auto theft drops as car makers fight back, Nassim Khadem, The Age, http://www.theage.com.au/articles/2004/03/27/1080330982083.html?from=storyrhs
- ^ FCAI throws microdot marking back to individual car-makers, Neil McDonald, goauto.com.au, http://www.gminsidenews.com/forums/showpost.php?s=cfcce00f942af1936a7e1096bd6d6074&p=277523&postcount=8
