Editing One-time pad (section)

=== Historical uses ===

One-time pads have been used in special circumstances since the early 1900s. In 1923, they were employed for diplomatic communications by the German diplomatic establishment.<ref>{{cite book| last=Kahn| first=David| title=The Codebreakers| publisher=[[Macmillan Publishers (United States)|Macmillan]]| year=1996| isbn=978-0-684-83130-5| pages=402–3 |author-link=David Kahn (writer)| title-link=The Codebreakers}}</ref> The [[Weimar Republic]] Diplomatic Service began using the method in about 1920. The breaking of poor [[Union of Soviet Socialist Republics|Soviet]] cryptography by the [[United Kingdom|British]], with messages made public for political reasons in two instances in the 1920s ([[All Russian Co-operative Society#The Arcos Affair of 1927|ARCOS case]]), appear to have caused the Soviet Union to adopt one-time pads for some purposes by around 1930. [[KGB]] spies are also known to have used pencil and paper one-time pads more recently. Examples include Colonel [[Rudolf Abel]], who was arrested and convicted in [[New York City]] in the 1950s, and the 'Krogers' (i.e., [[Morris Cohen (spy)|Morris]] and [[Lona Cohen]]), who were arrested and convicted of espionage in the [[United Kingdom]] in the early 1960s. Both were found with physical one-time pads in their possession.

A number of nations have used one-time pad systems for their sensitive traffic. [[Leo Marks]] reports that the British [[Special Operations Executive]] used one-time pads in World War II to encode traffic between its offices. One-time pads for use with its overseas agents were introduced late in the war.<ref name="marks" /> A few British one-time tape cipher machines include the [[Rockex]] and [[Noreen]]. The German [[Stasi]] Sprach Machine was also capable of using one time tape that East Germany, Russia, and even Cuba used to send encrypted messages to their agents.<ref name="Sprach Machine">{{cite news |title=Stasi Sprach Morse Machine |url=http://www.numbers-stations.com/sprach-machine |publisher=The Numbers Stations Research and Information Center |access-date=March 1, 2015 |url-status = dead|archive-url=https://web.archive.org/web/20150313143905/http://www.numbers-stations.com/sprach-machine |archive-date=March 13, 2015 |df=mdy-all }}</ref>

The [[World War II]] voice [[scrambler]] [[SIGSALY]] was also a form of one-time system. It added noise to the signal at one end and removed it at the other end. The noise was distributed to the channel ends in the form of large shellac records that were manufactured in unique pairs. There were both starting synchronization and longer-term phase drift problems that arose and had to be solved before the system could be used.<ref>{{Cite web |date=2019-02-24 |title=National Security Agency {{!}} Central Security Service > About Us > Cryptologic Heritage > Historical Figures and Publications > Publications > WWII > Sigsaly Story |url=https://www.nsa.gov/about/cryptologic-heritage/historical-figures-publications/publications/wwii/sigsaly-story/ |access-date=2022-03-27 |archive-url=https://web.archive.org/web/20190224044402/https://www.nsa.gov/about/cryptologic-heritage/historical-figures-publications/publications/wwii/sigsaly-story/ |archive-date=2019-02-24 }}</ref>

The [[Moscow-Washington hotline|hotline]] between [[Moscow]] and [[Washington, D.C.]], established in 1963 after the 1962 [[Cuban Missile Crisis]], used [[teleprinter]]s protected by a commercial one-time tape system. Each country prepared the keying tapes used to encode its messages and delivered them via their embassy in the other country. A unique advantage of the OTP in this case was that neither country had to reveal more sensitive encryption methods to the other.<ref>
{{cite book| last=Kahn| first=David| title=The Codebreakers| publisher=[[Macmillan Publishers (United States)|Macmillan]]| year=1967| isbn=978-0-684-83130-5| pages=715 ff |author-link=David Kahn (writer)| title-link=The Codebreakers}}
</ref>

U.S. Army Special Forces used one-time pads in Vietnam. By using Morse code with one-time pads and continuous wave radio transmission (the carrier for Morse code), they achieved both secrecy and reliable communications.<ref>{{cite journal |last1=Hieu |first1=Phan Duong |title=Cryptology during the French and American Wars in Vietnam |journal=Cryptologia |date=April 2007 |volume=41 |issue=6 |pages=1–21 |doi=10.1080/01611194.2017.1292825 |s2cid=3780267 |url=https://eprint.iacr.org/2016/1136.pdf |access-date=14 April 2020}}</ref>

Starting in 1988, the [[African National Congress]] (ANC) used disk-based one-time pads as part of a [[secure communication]] system between ANC leaders outside [[South Africa]] and in-country operatives as part of Operation Vula,<ref>"[http://www.radionetherlandsarchives.org/operation-vula-a-secret-dutch-network-against-apartheid/ Operation Vula: a secret Dutch network against apartheid]", Radio Netherlands Archives, September 9, 1999</ref> a successful effort to build a resistance network inside South Africa. Random numbers on the disk were erased after use. A Belgian flight attendant acted as courier to bring in the pad disks. A regular resupply of new disks was needed as they were used up fairly quickly. One problem with the system was that it could not be used for secure data storage. Later Vula added a stream cipher keyed by book codes to solve this problem.<ref>
{{Cite journal
 |first       = Tim
 |last        = Jenkin
 |date        = May–October 1995
 |title       = Talking to Vula: The Story of the Secret Underground Communications Network of Operation Vula
 |quote       = Our system was based on the one-time pad, though instead of having paper pads the random numbers were on a disk.
 |journal     = Mayibuye
 |url         = http://www.anc.org.za/show.php?id=4693
 |access-date  = 24 August 2014
 |url-status = dead|archive-url  = https://web.archive.org/web/20140826115901/http://www.anc.org.za/show.php?id=4693
 |archive-date = 2014-08-26
}}</ref>

A related notion is the [[code (cryptography)#One-time code|one-time code]]—a signal, used only once; e.g., "Alpha" for "mission completed", "Bravo" for "mission failed" or even "Torch" for "[[Operation Torch|Allied invasion of French Northern Africa]]"<ref>{{cite book
|title=The Secret Wireless War – The story of MI6 Communications 1939-1945
|last = Pidgeon |first = Geoffrey
|publisher = UPSO Ltd |isbn = 978-1-84375-252-3
|page = 249
|chapter = Chapter 28: Bill Miller – Tea with the Germans
|year = 2003 }}</ref> cannot be "decrypted" in any reasonable sense of the word. Understanding the message will require additional information, often 'depth' of repetition, or some [[traffic analysis]]. However, such strategies (though often used by real operatives, and [[baseball]] coaches)<ref>{{cite web |last1=Johnson |first1=Tim |title=What do all those hand signals mean? Inside the hidden language of baseball and softball |url=https://www.wausaudailyherald.com/story/sports/high-school/baseball/2018/04/24/what-do-all-those-hand-signals-mean-inside-hidden-language-baseball-and-softball/534843002/ |access-date=14 June 2024}}</ref> are not a cryptographic one-time pad in any significant sense.