Tap code: Difference between revisions

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The '''Tap Code''' is a [[cipher]], commonly used by prisoners in jail to communicate with one another. The method of communicating is usually by "tapping" either the metal bars or the walls inside the cell, hence its name. It is a very simple cipher, not meant to avoid interception, since the messages are sent in [[cleartext]].

{{contradict}} <!-- Invented in 1965, used in a book published 1941 is contradictory. -->

The '''Tap Code''' is a [[cipher]], commonly used by prisoners in jail to communicate with one another. The method of communicating is usually by "tapping" either the metal bars or the walls inside the cell, hence its name. It is a very simple cipher, not meant to avoid interception, since the messages are sent in [[cleartext]].

It[[United wasStates]] reportedly[[prisoners inventedof inwar]] Juneduring the [[1965Vietnam War]] are most known for having used the Tap Code. It was introduced in June 1965 by four [[POW]]sPOWs imprisonedheld in the [[Hanoi Hilton|Hoa Lo]], [[Vietnam"Hanoi Hilton"]] prison: [[Captain]] Carlyle ("Smitty") Harris, [[Lieutenant]] Phillip Butler, Lieutenant Robert Peel, and [[Lieutenant Commander]] Robert Shumaker.<ref Harrisname="pbs">{{cite rememberedweb an| [[United States Airurl=http://www.pbs.org/wgbh/amex/honor/sfeature/sf_tap.html Force|Air Force]] instructor who had shown him a cipher based on a title=''[[PolybiusAmerican squareExperience]],'': as''Return shownwith on the graph below. Each letter was communicated by tapping two numbersHonor'': the first designated the row (horizontal) and the second designated the column (vertical). The letterTap "X"Code was| usedpublisher=[[PBS]] to| breakdate=1999 up| sentences and the letter "C" replaced the letter "K".accessdate=2008-04-08}}</ref>

The origins of this encoding go back to the [[Polybius square]] of [[Ancient Greece]]. As the "knock code", it is said to have been used by [[nihilist]] prisoners of the [[Russia]]n [[Czar]]s.{{citeneeded}} The knock code is featured in [[Arthur Koestler]]'s classic 1941 work ''[[Darkness at Noon]]''.<ref>Koestler, Arthur, ''Darkness at Noon'' (1941). Translated by Daphne Hardy. See page 19 of the Bantam Publishing paperback, 1981 printing for more info.</ref> Smitty Harris had heard of the tap code being used by prisoners in [[World War II]]<ref name="au">{{cite news | url=http://www.au.af.mil/au/awc/awcgate/awc-pow.htm | title=Vets, Flyers discuss ideology, time in POW camps | author=Staff Sgt. Jason Tudor | publisher=[[Air Force News Service]] | date=1998-03-18 | accessdate=2008-04-08}}</ref> and remembered a [[United States Air Force]] instructor who had discussed it as well.<ref name="pbs"/>

The Tap Code is featured in [[Arthur Koestler]]'s classic work ''[[Darkness at Noon]]'', which was published in 1941. The prisoners refer to it as the knock code, but the technique is still the same.

In the Tap Code, each letter was communicated by tapping two numbers: the first designated the row (horizontal) and the second designated the column (vertical). The letter "X" was used to break up sentences and the letter "C" replaced the letter "K".

The Tap Code is outlined in the table below:

Line 36 ⟶ 37:

W A T E R

Because of the difficulty and length of time required for specifying a single letter, most prisoners devised [[abbreviations]] and [[acronyms]] for common items or phrases, such as "GN" for ''Good Night'', or "GBU" for ''God Bless You''.<ref name="pbs"/>

==References==

{{reflist}}

==External links==

==References==

* [http://www.airsoftgent.be/dbase/tapcode.htm The Tap Code]

* [http://www.braingle.com/brainteasers/codes/tapcode.php Online Tap Code Encoder/Decoder]

* Koestler, Arthur, ''Darkness at Noon'' (1941). Translated by Daphne Hardy. See page 19 of the Bantam Publishing paperback, 1981 printing for more info.

{{Crypto navbox | classical}}

[[Category:Classical ciphers]]

[[Category:Encodings]]