Tap code

Last updated
Latin alphabet tap code table
12345
1 A B C/K D E
2 F G H I J
3 L M N O P
4 Q R S T U
5 V W X Y Z

The tap code, sometimes called the knock code, is a way to encode text messages on a letter-by-letter basis in a very simple way. The message is transmitted using a series of tap sounds, hence its name. [1]

Contents

The tap code has been commonly used by prisoners to communicate with each other. The method of communicating is usually by tapping either the metal bars, pipes or the walls inside a cell.

Design

The tap code is based on a Polybius square using a 5×5 grid of letters representing all the letters of the Latin alphabet, except for K, which is represented by C.

Each letter is communicated by tapping two numbers, the first designating the row and the second (after a pause) designating the column. For example, to specify the letter "B", one taps once, pauses, and then taps twice. The listener only needs to discriminate the timing of the taps to isolate letters.

To communicate the word "hello", the cipher would be the following (with the pause between each number in a pair being shorter than the pause between letters):

HELLO
2, 3
1, 5
3, 1
3, 1
3, 4
•• •••   • •••••   ••• •   ••• •   ••• ••••

The letter "X" is used to break up sentences, and "K" for acknowledgements.

Because of the difficulty and length of time required for specifying a single letter, prisoners often devise abbreviations and acronyms for common items or phrases, such as "GN" for Good night, or "GBU" for God bless you. [2]

By comparison, despite its messages being shorter, Morse code is harder to send by tapping or banging. Its short and long signals can be improvised as taps and thumps, or short and long whistles or scraping sounds, but tap codes are simpler to learn and can be used in a wider variety of situations. [3] The tap system simply requires one to know the alphabet and the short sequence "AFLQV" (the initial letter of each row), without memorising the entire grid. For example, if a person hears four knocks, they can think "A... F... L... Q". If after a pause there are three knocks, they think "Q... R... S" to arrive at the letter S.

History

Cyrillic alphabet tap code [4]
123456
1 А Б В Г Д Е/Ё
2 Ж З И/Й К Л М
3 Н О П Р С Т
4 У Ф Х Ц Ч Ш
5 Щ Ъ/Ь Ы Э Ю Я

The origins of this encoding go back to the Polybius square of Ancient Greece. Like the "knock code", a Cyrillic script version is said to have been used by nihilist prisoners of the Russian czars. [5] The knock code is featured in Arthur Koestler's 1941 work Darkness at Noon . [6] Kurt Vonnegut's 1952 novel Player Piano also includes a conversation between prisoners using a form of tap code. The code used in the novel is more primitive and does not make use of the Polybius square (e.g. "P" consists of sixteen taps in a row).

United States prisoners of war during the Vietnam War are most known for having used the tap code. It was introduced in June 1965 by four POWs held in the Hỏa Lò ("Hanoi Hilton") prison: Captain Carlyle "Smitty" Harris, Lieutenant Phillip Butler, Lieutenant Robert Peel, and Lieutenant Commander Robert Shumaker. [2] [7] Harris had heard of the tap code being used by prisoners in World War II [8] and remembered a United States Air Force instructor who had discussed it as well. [2] [9]

In Vietnam, the tap code became more widely used than Morse; despite messages taking longer to send, the system was easier to learn and could be applied in a wider variety of situations. [3] Tap codes proved to be a very successful [10] way for otherwise isolated prisoners to communicate. [8] [11] POWs would use the tap code in order to communicate to each other between cells in a way which the guards would be unable to pick up on. [12] They used it to communicate everything from what questions interrogators were asking (in order for everyone to stay consistent with a deceptive story), to who was hurt and needed others to donate meager food rations. It was easy to teach and newly arrived prisoners became fluent in it within a few days. [13] [14] It was even used when prisoners were sitting next to each other but not allowed to talk, by tapping on another's thigh. [14] U.S. Navy Rear Admiral Jeremiah Denton developed a vocal tap code of coughs, sniffs and sneezes. [3] By overcoming isolation with the tap code, prisoners were said to be able to maintain a chain of command and keep up morale. [8] [15]

In 1980, a doctor sentenced to life in solitary confinement in Somalia used tap code to share the entirety of Tolstoy's Anna Karenina , nearly 2 million letters, via tap code with fellow prisoners. [16]

In the video game Metal Gear 2: Solid Snake , the tap code is used by Dr. Drago Pettrovich Madnar to communicate to Solid Snake through a cell wall.

In Season 2 Episode 2 of Person of Interest , the tap code is used by Harold Finch to discreetly leave breadcrumbs of his location to John Reese by encoding his location as tap code on a telephone.

In the video game Her Story , the main characters use the tap code to surreptitiously communicate.

In Season 2 Episode 14 of The Flash , the masked prisoner in Zoom's lair uses the tap code to try to communicate with the others.

In the film The Ice Road , the tap code is used on a metal pipe conduit by trapped miners to communicate with executives of the mining company.

Related Research Articles

<span class="mw-page-title-main">Morse code</span> Transmission of language with brief pulses

Morse code is a telecommunications method which encodes text characters as standardized sequences of two different signal durations, called dots and dashes, or dits and dahs. Morse code is named after Samuel Morse, one of the early developers of the system adopted for electrical telegraphy.

<span class="mw-page-title-main">Hỏa Lò Prison</span> Vietnamese Prison Camp

Hỏa Lò Prison was a prison in Hanoi originally used by the French colonists in Indochina for political prisoners, and later by North Vietnam for U.S. prisoners of war during the Vietnam War. During this later period, it was known to American POWs as the "Hanoi Hilton". Following Operation Homecoming, the prison was used to incarcerate Vietnamese dissidents and other political prisoners, including the poet Nguyễn Chí Thiện. The prison was demolished during the 1990s, although its gatehouse remains a museum.

<span class="mw-page-title-main">James Stockdale</span> US Navy admiral and aviator (1923–2005)

James Bond Stockdale was a United States Navy vice admiral and aviator who was awarded the Medal of Honor in the Vietnam War, during which he was a prisoner of war for over seven years.

<span class="mw-page-title-main">Polybius square</span> Type of code

The Polybius square, also known as the Polybius checkerboard, is a device invented by the ancient Greeks Cleoxenus and Democleitus, and made famous by the historian and scholar Polybius. The device is used for fractionating plaintext characters so that they can be represented by a smaller set of symbols, which is useful for telegraphy, steganography, and cryptography. The device was originally used for fire signalling, allowing for the coded transmission of any message, not just a finite number of predetermined options as was the convention before.

<span class="mw-page-title-main">Jeremiah Denton</span> US Navy admiral and politician (1924–2014)

Jeremiah Andrew Denton Jr. was an American politician and military officer who served as a U.S. Senator representing Alabama from 1981 to 1987. He was the first Republican to be popularly elected to a Senate seat in Alabama. Denton was previously a United States Navy rear admiral and naval aviator taken captive during the Vietnam War.

<span class="mw-page-title-main">James Robinson Risner</span> US Air Force general

Brigadier General James Robinson "Robbie" Risner was a fighter pilot in the United States Air Force, and a senior leader among U.S. prisoners of war during the Vietnam War.

<span class="mw-page-title-main">George Thomas Coker</span> United States Navy commander (born 1943)

George Thomas Coker is a retired United States Navy commander who was awarded the Navy Cross for extraordinary heroism as a prisoner of war (POW) during the Vietnam War. An Eagle Scout, he is noted for his devotion to Scouting.

<span class="mw-page-title-main">Operation Homecoming</span> 1973 return of American POWs from North Vietnam

Operation Homecoming was the return of 591 American prisoners of war (POWs) held by North Vietnam following the Paris Peace Accords that ended U.S. involvement in the Vietnam War.

<span class="mw-page-title-main">Doug Hegdahl</span> United States Navy sailor

Douglas Brent Hegdahl is a former United States Navy petty officer second class (E-5) who was held as a prisoner of war during the Vietnam War. After an early release, he was able to provide the names and personal information of about 256 fellow POWs, as well as reveal the conditions of the prisoner-of-war camp.

<span class="mw-page-title-main">John A. Dramesi</span> US Air Force officer, Vietnam War-era POW

John Arthur Dramesi was a United States Air Force (USAF) colonel who was held as a prisoner of war from 2 April 1967 to 4 March 1973 in both Hoa Lo Prison, known as "The Hanoi Hilton", and Cu Loc Prison, "The Zoo", during the Vietnam War.

<span class="mw-page-title-main">Norman C. Gaddis</span> United States general (1923–2024)

Norman Carl Gaddis was a United States Air Force officer, fighter pilot and prisoner of war. At the time he was shot down over North Vietnam, Gaddis was the most senior United States Air Force officer (Colonel).

<span class="mw-page-title-main">Lawrence N. Guarino</span>

Lawrence Nicholas "Larry" Guarino was a United States Air Force officer, and veteran of three wars. Shot down on his 50th combat mission, he spent more than eight years as a prisoner of war (POW) during the Vietnam War and earned the Air Force Cross.

<span class="mw-page-title-main">Alcatraz Gang</span>

The Alcatraz Gang was a group of eleven American prisoners of war (POW) held separately in Hanoi, North Vietnam during the Vietnam War because of their particular resistance to their North-Vietnamese military captors. These eleven POWs were: George Thomas Coker, USN; Jeremiah Denton, USN; Harry Jenkins, USN; Sam Johnson, USAF; George McKnight, USAF; James Mulligan, USN; Howard Rutledge, USN; Robert Shumaker, USN; James Stockdale, USN; Ron Storz, USAF; and Nels Tanner, USN.

<span class="mw-page-title-main">Leon F. "Lee" Ellis</span> Air Force colonel

Leon F. "Lee" Ellis is a retired United States Air Force colonel, award-winning author, speaker, and consultant. Ellis gained notoriety when, as a fighter pilot in the Vietnam War, he was shot down, captured, and spent 5+1⁄2 years as a prisoner of war in Hanoi and surrounding areas with former presidential candidate and Senator John McCain (R-AZ) and others. His capture occurred on November 7, 1967, and he was released on March 14, 1973. He was one of the youngest, junior members in the camps. Ellis is an international speaker and consultant on the subjects of leadership and human performance, organizational integrity, operational effectiveness, and personal accountability. He frequently consults with various organizations—from small businesses to Fortune 500 organizations on these subjects. Ellis' latest book, Leadership Behavior DNA: Discovering Natural Talents and Managing Differences was published in 2020 with co-author Hugh Massie. Engage with Honor: Building a Culture of Courageous Accountability published in 2016 and his last award-winning book, Leading with Honor: Leadership Lessons from the Hanoi Hilton published in 2012, share his POW experience and the leadership principles that helped him and his compatriots resist, survive, and return with honor. His previous book, Leading Talents, Leading Teams, was published by Northfield Publishing and shares in-depth team concepts on how to lead and manage based on individual, innate gifts and talents. Additionally, Lee has co-authored three additional books and workbooks on career planning.

<span class="mw-page-title-main">Robert H. Shumaker</span>

Robert Harper Shumaker is a retired rear admiral and naval aviator in the United States Navy. He spent eight years and one day as a prisoner of war (POW) in North Vietnam. He notably coined the term "Hanoi Hilton” for the notorious Hỏa Lò Prison.

The Hanoi March was a propaganda event held on July 6, 1966, involving U.S. prisoners of war during the Vietnam War. During the march, members of the North Vietnamese Army paraded 52 American POWs through the streets of Hanoi before tens of thousands of North Vietnamese civilians. The march soon deteriorated into near riot conditions, with North Vietnamese civilians beating the POWs along the 2 miles (3.2 km) route and their guards largely unable to control the melee.

Members of the United States armed forces were held as prisoners of war (POWs) in significant numbers during the Vietnam War from 1964 to 1973. Unlike U.S. service members captured in World War II and the Korean War, who were mostly enlisted troops, the overwhelming majority of Vietnam-era POWs were officers, most of them Navy, Air Force, and Marine Corps airmen; a relatively small number of Army enlisted personnel were also captured, as well as one enlisted Navy seaman, Petty Officer Doug Hegdahl, who fell overboard from a naval vessel. Most U.S. prisoners were captured and held in North Vietnam by the People's Army of Vietnam (PAVN); a much smaller number were captured in the south and held by the Việt Cộng (VC). A handful of U.S. civilians were also held captive during the war.

<span class="mw-page-title-main">Hayden Lockhart</span>

Hayden James Lockhart is a retired United States Air Force officer who is best known for being the first U.S. Air Force pilot to be shot down in North Vietnam.

<span class="mw-page-title-main">Phillip N. Butler</span> US POW in N. Vietnam for eight years, president Veterans for Peace

Phillip Neal "Phil" Butler is a retired United States Naval officer and pilot. He was the eighth-longest-held U.S. prisoner of war (POW) held in North Vietnam during the Vietnam War. Butler, who was forced to eject after a mid-air explosion on April 20, 1965, was a prisoner of war in North Vietnam until his release as part of Operation Homecoming in 1973. Butler was one of the five POWs credited with establishing the tap code. The code enabled the prisoners to communicate with each other.

Ronald E. Storz was a United States Air Force pilot and recipient of the Air Force Cross who died in captivity as a prisoner of war during the Vietnam War.

References

  1. ↑ The Handbook Of The SAS And Elite Forces. How The Professionals Fight And Win. Edited by Jon E. Lewis. p.199-Tactics And Techniques, Evasion, Capture And Escape. Robinson Publishing Ltd 1997. ISBN 1-85487-675-9
  2. 1 2 3 "'Return with Honor': The Tap Code". American Experience . PBS. 1999. Archived from the original on 2012-11-10. Retrieved 2008-04-08.
  3. 1 2 3 Denton, Jeremiah A.; Brandt, Ed (1976). When Hell Was in Session . New York: Reader's Digest Press. ISBN   0-88349-112-5.
  4. ↑ "Far Outliers: Russian Prison Tapping Code". April 14, 2005. Archived from the original on August 15, 2014. Retrieved August 8, 2014.
  5. ↑ David Kahn, The Codebreakers – The Story of Secret Writing. 1967. ISBN   978-0-684-83130-5.
  6. ↑ Koestler, Arthur, Darkness at Noon (1941). Translated by Daphne Hardy. See page 19 of the Bantam Publishing paperback, 1981 printing for more info.
  7. ↑ Borling, John (2013). Taps on the Walls: Poems from the Hanoi Hilton. Priztker Military Library: Master Wings Publishing. pp. 1–9. ISBN   978-0-615-65905-3.
  8. 1 2 3 Staff Sgt. Jason Tudor (1998-03-18). "Vets, Flyers discuss ideology, time in POW camps". Air Force News Service. Archived from the original on 2007-12-03. Retrieved 2008-04-08.
  9. ↑ Townley, Alvin. (4 February 2014). Defiant : the POWs who endured Vietnam's most infamous prison, the women who fought for them, and the one who never returned (First edition : February 2014 ed.). New York. ISBN   9781250006530. OCLC   862575088.{{cite book}}: CS1 maint: location missing publisher (link)
  10. ↑ Peterson, Gordon I; Taylor, David C (March 2016). "Intelligence Support to Communications with US POW's in Vietnam". Studies in Intelligence. 60. Center for the Study of Intelligence Publications: 1–15. Archived from the original on 2019-05-08. Retrieved 2019-05-23.
  11. ↑ Fretwell, Peter; Kiland, Taylor Baldwin (2013). Lessons from the Hanoi Hilton: Six Characteristics of High Performance Teams. Annapolis, Maryland: Naval Institute Press. pp. 63–67. ISBN   978-1-61251-217-4.
  12. ↑ Hirsch, James S (2004). Two Souls Indivisible: The Friendship that saved two POW's in Vietnam . New York: Houghton-Mifflin. pp.  161-162. ISBN   0618273484.
  13. ↑ McCain, John; Mark Salter (1999). Faith of My Fathers. Random House. pp.  211–12. ISBN   0-375-50191-6.
  14. 1 2 Brace, Ernest C. (1988). A Code to Keep: The true story of America's longest held civilian prisoner of war in Vietnam. St. Martin's Press. pp. 171–72, 187–88. ISBN   0-7090-3560-8.
  15. ↑ Naughton, Robert J (1975). "Motivational Factors of American Prisoners of War Held by the Democratic Republic of Vietnam". Naval War College Review. 28. Archived from the original on 2019-05-04. Retrieved 2019-05-04.
  16. ↑ "Rough Translation: How 'Anna Karenina' Saved A Somali Inmate's Life". NPR . 2017-09-11. Archived from the original on 2023-06-26.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.