Microdot
{{Short description|Steganograph method of hiding messages}}
{{other uses}}
File:German microdots World War II Mexico Spain.jpg to Lisbon during World War II, but was intercepted by Allied intelligence.]]
A microdot is text or an image substantially reduced in size to prevent detection by unintended recipients. Microdots are normally circular and around {{convert|1|mm}} in diameter but can be made into different shapes and sizes and made from various materials such as polyester or metal. The name comes from microdots often having been about the size and shape of a typographical dot, such as a period or the tittle of a lowercase i or j. Microdots are, fundamentally, a steganographic approach to message protection.
History
File:March 2020 Microdot Object (49673631061).jpg until the spy's arrest in 1942. (FBI collection)]]
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.Kipper, Gregory. Investigator's Guide to Steganography. Boca Raton: Auerbach Publications, 2003. {{ISBN?}}
Improvement in technology since then has made even smaller miniaturization possible.{{Cite book | last= Hayhurst | first= J. D. | title= The Pigeon Post into Paris 1870–1871 | publisher= (privately published) | year= 1970 | url= http://www.cix.co.uk/~mhayhurst/jdhayhurst/pigeon/pigeon.html | archive-date= 2016-06-08 | access-date= 2006-11-02 | archive-url= https://web.archive.org/web/20160608220722/http://www.cix.co.uk/~mhayhurst/jdhayhurst/pigeon/pigeon.html | url-status= dead }}
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.{{Cite book | url= http://www.ischool.berkeley.edu/~buckland/goldberg.html | last= Buckland | first= Michael | title= Emanuel Goldberg and His Knowledge Machine: Information, Invention, and Political Forces | series= New Directions in Information Management | publisher= Libraries Unlimited | year= 2006 | archive-date= 2007-07-06 | access-date= 2007-05-08 | archive-url= https://web.archive.org/web/20070706005308/http://www.ischool.berkeley.edu/~buckland/goldberg.html | url-status= dead }}{{cite journal |last1=Goldberg |first1=Emanuel |title=A new process of micro-photography |journal=British Journal of Photography |date=13 August 1916|volume=73|issue=3458|pages=462–465}}{{cite book |last1=Stevens |first1=G. W. W. |title=Microphotography: Photography and photofabrication at extreme resolution |date=1968 |publisher=Chapman & Hall |location=London |page=46 |edition=2 nd}}{{ISBN?}}
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".{{cite journal |last1=Hoover |first1=J. Edgar |title=The enemy's masterpiece of espionage |journal=Reader's Digest |date=1946 |volume=48 |issue=April |pages=1–6 }} This article was reprinted, translated, and widely and uncritically cited in the literature on espionage. There never was a Professor Zapp at that university;{{cite book |last1=White |first1=William |title=The microdot: History and application |date=1992 |publisher=Phillips Publications |location=Williamstown, NJ |pages=49–56 | isbn= 0932572197}} 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.{{cite web|url=http://southtahoenow.com/story/09/16/2015/high-tech-anti-theft-dots-help-south-lake-tahoe-police|title=High tech anti-theft dots to help South Lake Tahoe Police|website=South Tahoe Now|date=17 September 2015 |access-date=17 August 2018}}{{cite web|url=http://www.dailydemocrat.com/article/NI/20150617/NEWS/150619902|title='Anti-Theft Dots' latest weapon against crime|date=12 August 2018|access-date=17 August 2018}}{{cite web|url=http://www.local8now.com/home/headlines/Alcoa-Police-using-new-DNA-system-for-returning-stolen-property-330967012.html|title=Alcoa Police using new 'DNA' system for returning stolen property|first=Steven|last=Powell|access-date=17 August 2018|archive-date=2 April 2017|archive-url=https://web.archive.org/web/20170402170034/http://www.local8now.com/home/headlines/Alcoa-Police-using-new-DNA-system-for-returning-stolen-property-330967012.html|url-status=dead}}{{cite web|url=http://wtkr.com/2015/10/26/can-these-little-stickers-help-police-track-down-your-stolen-items/|title=Can these little stickers help police track down your stolen items?|date=26 October 2015|access-date=17 August 2018}}{{cite web|url=http://www.alaskapublic.org/2015/11/27/north-pole-police-launch-new-anti-theft-program/|title=North Pole police launch new anti-theft program|first=Dan Bross, KUAC -|last=Fairbanks|date=28 November 2015|access-date=17 August 2018}} 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.{{Cite web|url=http://securityondots.com/microdot.html|title=Microdot Technology || Security on Dots}}
Some printers print, in addition to the document contents requested, tiny yellow dots containing the printer serial number and a time stamp.{{cite web|url=https://www.eff.org/pages/list-printers-which-do-or-do-not-display-tracking-dots|title=List of Printers Which Do or Do Not Display Tracking Dots|date=19 September 2007|publisher=Electronic Frontier Foundation|access-date=2018-12-10|archive-date=2017-01-20|archive-url=https://web.archive.org/web/20170120103601/https://www.eff.org/pages/list-printers-which-do-or-do-not-display-tracking-dots|url-status=live}}
See also
References
{{reflist}}
External links
- [http://www.wonko.net/microdot2results.html Microdot photography]
{{Espionage}}