Microdot

History

In 1870 during the Franco-Prussian War, Paris was under siege and messages were sent by carrier pigeon. Parisian photographer René Dagron used microfilm to permit each pigeon to carry a high volume of messages, as pigeons can carry little weight.

Improvement in technology since then has made even smaller miniaturization possible.

At the 1925 International Congress of Photography in Paris, Emanuel Goldberg presented a method of producing extreme reduction microdots using a two-stage process. First, an initial reduced negative was made, then the image of the negative was projected from the eyepiece of a modified microscope onto a collodium emulsion where the microscope specimen slide would be. The reduction was such that a page of text would be legibly reproduced in an area of 0.01 mm2. This density is comparable to the entire text of the Bible fifty times over in one square inch. Goldberg's "Mikrat" (microdot) was prominently reported at the time in English, French and German publications.

A technique comparable to modern microdots for steganographic purposes was first used in Germany during the Interwar period. It was also 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, as this was even harder for counter-espionage agents to find.

A popular article on espionage by J. Edgar Hoover in the Reader's Digest in 1946 attributed invention of microdots to "the famous Professor Zapp at the Technical University Dresden". This article was reprinted, translated, and widely and uncritically cited in the literature on espionage. There never was a Professor Zapp at that university; Hoover's Zapp has been wrongly identified with Walter Zapp, inventor of the Minox camera, which was used by spies but did not make microdots. Hoover appears to have conflated Emanuel Goldberg, who was a professor in Dresden, with Kurt Zapp who, late in World War II, was in Dresden and taught spies how to make microdots.

Modern usage

Microdot identification is a process in which tiny identification tags are etched or coded with a unique serial number or, for use on vehicles, with a vehicle identification number (VIN) or asset identification number. In South Africa it is a legal requirement to have a microdot fitted to all new vehicles sold since September 2012 and to all vehicles that require police clearance.

Some printers print, in addition to the document contents requested, tiny yellow dots containing the printer serial number and a time stamp.

References

References

1. Kipper, Gregory. ''Investigator's Guide to Steganography''. Boca Raton: Auerbach Publications, 2003. {{ISBN?
2. Hayhurst, J. D.. (1970). "The Pigeon Post into Paris 1870–1871". (privately published).
3. Buckland, Michael. (2006). "Emanuel Goldberg and His Knowledge Machine: Information, Invention, and Political Forces". Libraries Unlimited.
4. (13 August 1916). "A new process of micro-photography". British Journal of Photography.
5. (1968). "Microphotography: Photography and photofabrication at extreme resolution". Chapman & Hall.
6. (1946). "The enemy's masterpiece of espionage". Reader's Digest.
7. (1992). "The microdot: History and application". Phillips Publications.
8. (17 September 2015). "High tech anti-theft dots to help South Lake Tahoe Police".
9. (12 August 2018). "'Anti-Theft Dots' latest weapon against crime".
10. Powell, Steven. "Alcoa Police using new 'DNA' system for returning stolen property".
11. (26 October 2015). "Can these little stickers help police track down your stolen items?".
12. Fairbanks, Dan Bross, KUAC -. (28 November 2015). "North Pole police launch new anti-theft program".
13. "Microdot Technology || Security on Dots".
14. (19 September 2007). "List of Printers Which Do or Do Not Display Tracking Dots". [[Electronic Frontier Foundation]].