Editing Lorenz cipher

{{Short description|Cipher machines used by the German Army during World War II}}
{{Use dmy dates|cs1-dates=ly|date=June 2015}}
[[File:Lorenz-SZ42-2.jpg|300px|right|upright=1.35|thumbnail|The Lorenz SZ42 machine with its covers removed. [[Bletchley Park]] museum]]
The '''Lorenz SZ40''', '''SZ42a''' and '''SZ42b''' were German [[Rotor machine|rotor]] [[stream cipher]] machines used by the [[German Army (Wehrmacht)|German Army]] during [[World War II]].  They were developed by [[C. Lorenz AG]] in [[Berlin]]. The model name ''SZ'' is derived from ''Schlüssel-Zusatz'', meaning ''cipher attachment''. The instruments implemented a [[Gilbert Vernam#The Vernam cipher|Vernam]] [[stream cipher]].

British [[cryptanalyst]]s, who referred to encrypted German [[Electrical telegraph|teleprinter]] traffic as [[Fish (cryptography)|''Fish'']], dubbed the machine and its traffic '''''Tunny''''' (meaning tunafish) and deduced its logical structure three years before they saw such a machine.<ref>{{Harvnb|Hinsley|1993|p=141}}</ref>

The SZ machines were in-line attachments to standard [[teleprinter]]s. An experimental link using SZ40 machines was started in June 1941. The enhanced SZ42 machines were brought into substantial use from mid-1942 onwards for high-level communications between the [[Oberkommando der Wehrmacht|German High Command]] in [[Wünsdorf]] close to Berlin, and Army Commands throughout occupied Europe.<ref>{{Harvnb|Hinsley|1993|p=142}}</ref> The more advanced SZ42A came into routine use in February 1943 and the SZ42B in June 1944.{{sfn|Copeland|2006|pp=38, 39|loc="The German Tunny Machine"}}

[[Radioteletype]] (RTTY) rather than land-line circuits was used for this traffic.<ref name = "GRoT11A4" >{{Harvnb|Good|Michie|Timms|1945|p=4}} of ''German Tunny''</ref> These [[Frequency-shift keying#Audio frequency-shift keying|audio frequency shift keying]] non-[[Morse code|Morse]] (NoMo) messages were picked up by Britain's [[Y-stations]] at [[Knockholt]] in Kent, its outstation at [[Higher Wincombe]]<ref name="Kenworthy">{{cite web|url=https://discovery.nationalarchives.gov.uk/details/r/C11205560|title=The National Archives: The interception of German Teleprinter Communications at Foreign Office Station Knockholt - Piece details HW 50/79|access-date=2023-12-15}}</ref> in Wiltshire, and at [[Denmark Hill]] in south London, and forwarded to the [[Government Communications Headquarters#Government Code and Cypher School|Government Code and Cypher School]] at [[Bletchley Park]] (BP). Some were deciphered using hand methods before the process was partially automated, first with [[Heath Robinson (codebreaking machine)|Robinson machines]] and then with the [[Colossus computer]]s.<ref>{{Harvnb|Good|1993|pp=160–165}}</ref> The deciphered Lorenz messages made one of the most significant contributions to British ''[[Ultra (cryptography)|Ultra]]'' [[military intelligence]] and to [[Allies of World War II|Allied]] victory in Europe, due to the high-level strategic nature of the information that was gained from Lorenz decrypts.<ref>{{Cite web|url=https://cs.stanford.edu/people/eroberts/courses/soco/projects/colossus/history.html|title=The History of the Lorenz Cipher and the Colossus Machine|website=Stanford University|access-date=9 September 2018}}</ref>

==History==
After the Second World War, a group of British and US cryptanalysts entered Germany with the front-line troops to capture the documents, technology and personnel of the various German signal intelligence organizations before these secrets could be destroyed, looted, or captured by the Soviets. They were called the [[TICOM|Target Intelligence Committee]]: TICOM.{{sfn|Parrish|1986|p=276}}{{sfn|Rezabek|2017|loc=I Introduction: Origin of TICOM}}

From captured German cryptographers Drs Huttenhain and Fricke they learnt of the development of the SZ40 and SZ42 a/b.{{sfn|Huttenhain|Fricke|1945|pp=16-19}} The design was for a machine that could be attached to any teleprinter. The first machine was referred to as the SZ40 (old type) which had ten rotors with fixed cams. It was recognised that the security of this machine was not great. The definitive SZ40 had twelve rotors with movable cams. The rightmost five rotors were called ''Spaltencäsar'' but named the ''Chi'' wheels by [[W. T. Tutte|Bill Tutte]]. The leftmost five were named ''Springcäsar'', ''Psi'' wheels to Tutte. The middle two ''Vorgeleger'' rotors were called ''Mu'' or motor wheels by Tutte.

The five data bits of each [[ITA2]]-coded telegraph character were processed first by the five ''chi'' wheels and then further processed by the five ''psi'' wheels. The cams on the wheels reversed the value of a bit if in the raised position, but left it unchanged if in the lowered position.

==Vernam cipher==
{{Main|Gilbert Vernam}}
[[Gilbert Vernam]] was an [[AT&T Corporation|AT&T]] [[Bell Labs]] research engineer who, in 1917, invented a cipher system in which the plaintext bitstream is enciphered by combining it with a random or pseudorandom bitstream (the "keystream") to generate the ciphertext. This combination is done using the [[Boolean algebra (logic)|Boolean]] [[Exclusive or|"exclusive or" (XOR)]] function, symbolised by ⊕.<ref>{{Harvnb|Klein|p=2}}</ref> This is represented by the following "[[truth table]]", where 1 represents "true" and 0 represents "false".

{| class="wikitable" style="text-align:center; margin: 0 auto"
|+ XOR truth table
|-
!colspan="2" | Input || rowspan="2" style="width: 70px;" | A ⊕ B
|-
!style="width: 45px;" | A || style="width: 45px;" | B
|-
| 0 || 0 || 0
|-
| 0 || 1 || 1
|-
| 1 || 0 || 1
|-
| 1 || 1 || 0
|}

Other names for this function are: Not equal (NEQ), [[Modular arithmetic|modulo]] 2 addition (without 'carry') and modulo 2 subtraction (without 'borrow').

Vernam's cipher is a [[symmetric-key algorithm]], i.e. the same [[Key (cryptography)|key]] is used both to encipher [[plaintext]] to produce the [[ciphertext]] and to decipher ciphertext to yield the original plaintext:

{{block indent|1=plaintext ⊕ key = ciphertext}}

and:

{{block indent|1=ciphertext ⊕ key = plaintext}}

This produces the essential reciprocity that allows the same machine with the same settings to be used for both encryption and decryption.

Vernam's idea was to use conventional telegraphy practice with a paper tape of the plaintext combined with a paper tape of the key. Each key tape would have been unique (a [[One-time pad|one-time tape]]), but generating and distributing such tapes presented considerable practical difficulties. In the 1920s four men in different countries invented rotor cipher machines to produce a key stream to act instead of a tape.<ref>{{Harvnb|Klein|p=3}}</ref> The 1940 Lorenz SZ40/42 was one of these.<ref name = "GRoT11B10">{{Harvnb|Good|Michie|Timms|1945|p=10}} of ''German Tunny''</ref>

==Operating Principle==
The logical functioning of the Tunny system was worked out well before the Bletchley Park cryptanalysts saw one of the machines—which only happened in 1945, as Germany was surrendering to the Allies.<ref name=Sale>{{ Citation | last = Sale | first = Tony | author-link = Anthony Sale | title = The Lorenz Cipher and how Bletchley Park broke it | url = http://www.codesandciphers.org.uk/lorenz/fish.htm | access-date = 21 October 2010 }}</ref>
[[Image:SZ42-6-wheels-lightened.jpg|right|400px|thumbnail|The Lorenz SZ machines had 12 wheels each with a different number of cams (or "pins").
{|class="wikitable" | border=1 
|-
! [[Cipher Department of the High Command of the Wehrmacht|OKW/''Chi'']]<br>wheel name
|A||B||C||D||E||F||G||H||I||K||L||M
|-
! BP wheel<br>name{{sfn|Good|Michie|Timms|1945|loc = 1 Introduction: 11 German Tunny, 11B The Tunny Cipher Machine, p. 6}}
| align="center" | ψ<sub>1</sub>
| align="center" | ψ<sub>2</sub>
| align="center" | ψ<sub>3</sub>
| align="center" | ψ<sub>4</sub>
| align="center" | ψ<sub>5</sub>
| align="center" | μ<sub>37</sub>
| align="center" | μ<sub>61</sub>
| align="center" | χ<sub>1</sub>
| align="center" | χ<sub>2</sub>
| align="center" | χ<sub>3</sub>
| align="center" | χ<sub>4</sub>
| align="center" | χ<sub>5</sub>
|-
! Number of<br>cams (pins)
|43||47||51||53||59||37||61||41||31||29||26||23
|}
]]

The SZ machine served as an in-line attachment to a standard Lorenz teleprinter. It had a metal base {{convert|19|×|15.5|in|abbr=on|cm|0}} and was {{convert|17|in|abbr=on|cm|0}} high.<ref name = "GRoT11B10"/>  The teleprinter characters consisted of five data [[bit]]s (or "impulses"), encoded in the [[Baudot code#ITA2|International Telegraphy Alphabet No. 2 (ITA2)]]. The SZ machine generated a stream of [[pseudorandom number generator|pseudorandom]] characters as the key that was combined with the plaintext input characters to form the ciphertext output characters. The combination was by means of the XOR (or modulo 2 addition) process.<ref name = "GRoT11B6">{{Harvnb|Good|Michie|Timms|1945|p=6}} of ''German Tunny''</ref>

The key stream consisted of two component parts that were XOR-ed together. These were generated by two sets of five wheels which rotated together. The Bletchley Park cryptanalyst Bill Tutte called these the ''χ'' ("[[Chi (letter)|''chi'']]") wheels, and the ''ψ'' ("[[Psi (letter)|''psi'']]") wheels. Each wheel had a series of cams (or "pins") around their circumference. These cams could be set in a raised (active) or lowered (inactive) position. In the raised position they generated a '1' which reversed the value of a bit, in the lowered position they generated a '0' which left the bit unchanged.{{sfn|Churchhouse|2002|pp=156,157}} The number of cams on each wheel equalled the number of impulses needed to cause them to complete a full rotation. These numbers are all [[Coprime|co-prime]] with each other, giving the longest possible time before the pattern repeated. This is the product of the number of positions of the wheels. For the set of ''χ'' wheels it was 41 × 31 × 29 × 26 × 23 = 22,041,682 and for the ''ψ'' wheels it was 43 × 47 × 51 × 53 × 59 = 322,303,017. The number of different ways that all twelve wheels could be set was {{val|1.603|e=19}} i.e. 16 billion billion.

The set of five ''χ'' wheels all moved on one position after each character had been enciphered. The five ''ψ'' wheels, however, advanced intermittently. Their movement was controlled by the two ''μ'' ("[[Mu (letter)|''mu'']]") or "motor" wheels in series.<ref name = "GRoT11B7">{{Harvnb|Good|Michie|Timms|1945|p=7}} of ''German Tunny''</ref> The SZ40 ''μ''<sub>61</sub> motor wheel stepped every time but the ''μ''<sub>37</sub> motor wheel stepped only if the first motor wheel was a '1'. The ''ψ'' wheels then stepped only if the second motor wheel was a '1'.<ref>{{Citation |last= Roberts |first= Eric |author-link= Eric Roberts |title= The Lorenz Schluesselzusatz SZ40/42 |publisher= Stanford University |url= https://cs.stanford.edu/people/eroberts/courses/soco/projects/2008-09/colossus/lorenzmachine.html }}</ref> The SZ42A and SZ42B models added additional complexity to this mechanism, known at Bletchley Park as ''Limitations''. Two of the four different limitations involved characteristics of the plaintext and so were [[Autokey cipher|autoclaves]].<ref>{{Harvnb|Good|Michie|Timms|1945|p=8}} of ''German Tunny''</ref>

The key stream generated by the SZ machines thus had a ''χ'' component and a ''ψ'' component. Symbolically, the key that was combined with the plaintext for enciphering and with the ciphertext for deciphering, can be represented as follows.<ref name = "GRoT11B7" />

::::key = ''χ''-key ⊕ ''ψ''-key

However to indicate that the ''ψ'' component often did not change from character to character, the term ''extended psi'' was used, symbolised as: ''Ψ'''. So enciphering can be shown symbolically as:

::::plaintext ⊕ ''χ''-stream ⊕ ''ψ'''-stream = ciphertext

and deciphering as:

::::ciphertext ⊕ ''χ''-stream ⊕ ''ψ'''-stream = plaintext.

==Operation==
[[File:Lorenz Cams.jpg|right|upright=1.35|thumbnail|Cams on wheels 9 and 10 showing their raised (active) and lowered (inactive) positions. An active cam reversed the value of a bit (0→1 and 1→0).]]
Each "Tunny" link had four SZ machines with a transmitting and a receiving teleprinter at each end. For enciphering and deciphering to work, the transmitting and receiving machines had to be set up identically. There were two components to this; setting the patterns of cams on the wheels and rotating the wheels for the start of enciphering a message. The cam settings were changed less frequently before summer 1944. The ''ψ'' wheel cams were initially only changed quarterly, but later monthly, the ''χ'' wheels were changed monthly but the motor wheel patterns were changed daily. From 1 August 1944, all wheel patterns were changed daily.<ref name = "GRoT11E14" >{{Harvnb|Good|Michie|Timms|1945|p=14}} of ''German Tunny''</ref>

Initially the wheel settings for a message were sent to the receiving end by means of a 12-letter [[Cryptanalysis#Indicator|indicator]] sent un-enciphered, the letters being associated with wheel positions in a book. In October 1942, this was changed to the use of a book of single-use settings in what was known as the QEP book. The last two digits of the QEP book entry were sent for the receiving operator to look up in his copy of the QEP book and set his machine's wheels. Each book contained one hundred or more combinations. Once all the combinations in a QEP book had been used it was replaced by a new one.{{sfn|Copeland|2006|p=45|loc="The German Tunny Machine"}} The message settings should never have been re-used, but on occasion they were, providing a "depth", which could be utilised by a cryptanalyst.<ref>{{Harvnb|Churchhouse|2002|p=34}}</ref>

As was normal telegraphy practice, messages of any length were keyed into a [[teleprinter]] with a [[Punched tape|paper tape]] perforator. The typical sequence of operations would be that the sending operator would punch up the message, make contact with the receiving operator, use the ''EIN / AUS'' switch on the SZ machine to connect it into the circuit, and then run the tape through the reader.<ref name = "GRoT11B10" /> At the receiving end, the operator would similarly connect his SZ machine into the circuit and the output would be printed up on a continuous sticky tape. Because this was the practice, the plaintext did not contain the characters for "carriage return", "line feed" or the null (blank tape, 00000) character.<ref name = "GRoT11A4" />

==Cryptanalysis==
{{Main|Cryptanalysis of the Lorenz cipher}}
[[File:British Tunny Rebuild.jpg|right|thumbnail|upright=1.35|A rebuilt British Tunny at [[The National Museum of Computing]], [[Bletchley Park]]. It emulated the functions of the Lorenz SZ40/42, producing printed cleartext from ciphertext input.]]
British cryptographers at [[Bletchley Park]] had deduced the operation of the machine by January 1942 without ever having seen a Lorenz machine, a feat made possible thanks to mistakes made by German operators.

===Interception===
Tunny traffic was known by [[Y Service|Y Station]] operators used to listening to [[Morse code]] transmission as "new music". Its interception was originally concentrated at the Foreign Office Y Station operated by the [[Metropolitan Police]] at [[Denmark Hill]] in [[Camberwell]], London. But due to lack of resources at this time (around 1941), it was given a low priority. A new Y Station, [[Knockholt]] in [[Kent]], was later constructed specifically to intercept Tunny traffic so that the messages could be efficiently recorded and sent to Bletchley Park.<ref>{{Harvnb|Good|Michie|Timms|1945|p=281}} in ''Knockholt''</ref> The head of Y station, [[Harold Kenworthy]], moved to head up Knockholt. He was later promoted to head the Foreign Office Research and Development Establishment (F.O.R.D.E).

===Code breaking===
On 30 August 1941, a message of some 4,000 characters was transmitted from [[Athens]] to [[Vienna]]. However, the message was not received correctly at the other end. The receiving operator then sent an uncoded request back to the sender asking for the message to be retransmitted. This let the codebreakers know what was happening.

The sender then retransmitted the message but, critically, did not change the key settings from the original "HQIBPEXEZMUG".  This was a forbidden practice; using a different key for every different message is critical to any stream cipher's security.  This would not have mattered had the two messages been identical, however the second time the operator made a number of small alterations to the message, such as using abbreviations, making the second message somewhat shorter.

From these two related ciphertexts, known to cryptanalysts as a [[Cryptanalysis#Depth|depth]], the veteran cryptanalyst [[John Tiltman|Brigadier John Tiltman]] in the Research Section teased out the two plaintexts and hence the [[keystream]]. But even almost 4,000 characters of key was not enough for the team to figure out how the stream was being generated; it was just too complex and seemingly random.

After three months, the Research Section handed the task to mathematician [[W. T. Tutte|Bill Tutte]]. He applied a technique that he had been taught in his cryptographic training, of writing out the key by hand and looking for repetitions. Tutte did this with the original teleprinter 5-bit [[Baudot code#ITA2|International Telegraph Alphabet No. 2 (ITA2)]] (which was a development of the [[Baudot code#Baudot code (ITA1)|Baudot code (ITA1)]]), which led him to his initial breakthrough of recognising a 41-bit repetition.<ref name=Sale/><ref>{{Harvnb|Tutte|1998|pp=356, 357}}</ref> Over the following two months up to January 1942, Tutte and colleagues worked out the complete logical structure of the cipher machine. This remarkable piece of [[reverse engineering]] was later described as "one of the greatest intellectual feats of World War II".<ref name=Sale/>

After this cracking of Tunny, a special team of code breakers was set up under [[Ralph Tester]], most initially transferred from [[Alan Turing]]'s [[Hut 8]]. The team became known as the [[Testery]]. It performed the bulk of the subsequent work in breaking Tunny messages, but was aided by machines in the complementary section under [[Max Newman]] known as the [[Newmanry]].<ref>{{Harvnb|Roberts|2009}}</ref>

===Decryption machines===
Several complex machines were built by the British to aid the attack on Tunny. The first was the [[British Tunny]].<ref>{{Harvnb|Halton|1993}}</ref><ref>[https://www.theregister.co.uk/2011/05/26/bletchley_park_tunny_rebuild_project/ Bletchley Park completes epic Tunny machine] The Register,  [https://www.theregister.co.uk/2011/05/26/ 26 May 2011], Accessed May 2011</ref> This machine was designed by Bletchley Park, based on the [[reverse engineering]] work done by Tiltman's team in the Testery, to emulate the Lorenz Cipher Machine. When the pin wheel settings were found by the Testery, the Tunny machine was set up and run so that the messages could be printed.

A family of machines known as "[[Heath Robinson (codebreaking machine)|Robinsons]]" were built for the Newmanry. These used two [[paper tape]]s, along with logic circuitry, to find the settings of the ''χ'' pin wheels of the Lorenz machine.{{sfn|Copeland|2006|p=66|loc="Machine against Machine"}} The Robinsons had major problems keeping the two paper tapes synchronized and were relatively slow, reading only 2,000 characters per second.
[[File:ColossusRebuild 11.jpg|thumb|A team led by [[Anthony Sale|Tony Sale]] (right) reconstructed a Colossus (Mark II) at Bletchley Park. Here, in 2006, Sale supervises the breaking of an enciphered message with the completed machine.]]
The most important machine was the [[Colossus computer|Colossus]] of which ten were in use by the war's end, the first becoming operational in December 1943. Although not fully programmable, they were far more efficient than their predecessors, representing advances in electronic digital [[computer]]s. The [[Colossus computer|Colossus]] computers were developed and built by [[Tommy Flowers]], of the [[Dollis Hill]] [[Post Office Research Station]], using algorithms developed by [[W.T. Tutte|Bill Tutte]] and his team of mathematicians.<ref>{{cite web|url=https://uwaterloo.ca/combinatorics-and-optimization/about/professor-william-t-tutte/biography-professor-tutte#bletchley|title=Biography of Professor Tutte - Combinatorics and Optimization|date=13 March 2015|access-date=2017-05-13 |archive-date=2019-08-19 |archive-url=https://web.archive.org/web/20190819115149/https://uwaterloo.ca/combinatorics-and-optimization/about/professor-william-t-tutte/biography-professor-tutte#bletchley|url-status=dead}}</ref> Colossus proved to be efficient and quick against the twelve-rotor Lorenz SZ42 on-line teleprinter cipher machine.

Some influential figures had doubts about his proposed design for the decryption machine, and Flowers  proceeded with the project while partly funding it himself.<ref>{{cite book|last=Boden|first=Margaret Ann|title=Mind as Machine: A History of Cognitive Science|url=https://books.google.com/books?id=yRyETy43AdQC&q=TOMMY+FLOWERS+built+at+his+own+expense+colossus&pg=PA159|publisher=Clarendon Press |location=Oxford|date=2006|page=159|isbn=9780199543168}}</ref><ref>{{cite book |last=Atkinson|first=Paul |date=2010|title=Computer|location=UK|publisher=Reaktion Books|isbn=9781861897374 |url=https://books.google.com/books?id=D5H_OsxEywwC |page=29}}</ref> Like the later [[ENIAC]] of 1946, Colossus did not have a [[stored program]], and was programmed through plugboards and jumper cables. It was faster, more reliable and more capable than the Robinsons, so speeding up the process of finding the Lorenz ''χ'' pin wheel settings. Since Colossus generated the putative keys electronically, it only had to read one tape. It did so with an optical reader which, at 5,000 characters per second, was driven much faster than the Robinsons' and meant that the tape travelled at almost 30 miles per hour (48&nbsp;km/h).<ref>{{Harvnb|Flowers|2006|p=100}}</ref> This, and the clocking of the electronics from the optically read paper tape sprocket holes, completely eliminated the Robinsons' synchronisation problems. Bletchley Park management, which had been sceptical of Flowers's ability to make a workable device, immediately began pressuring him to construct another. After the end of the war, Colossus machines were dismantled on the orders of Winston Churchill,<ref>Verdict of Peace: Britain Between Her Yesterday and the  future, Correlli Barnett, 2002</ref> but GCHQ retained two of them.{{sfn|Copeland|2006|p=173}}

===Testery executives and Tunny codebreakers===
* [[Ralph Tester]]: linguist and head of Testery
* [[Jerry Roberts]]: shift-leader, linguist and senior codebreaker
* Peter Ericsson: shift-leader, linguist and senior codebreaker
* Victor Masters: shift-leader
* Denis Oswald: linguist and senior codebreaker
* [[Peter Hilton]]: codebreaker and mathematician
* [[Peter Benenson]]: codebreaker
* Peter Edgerley: codebreaker
* John Christie: codebreaker
* John Thompson: codebreaker
* [[Roy Jenkins]]: codebreaker
* [[Shaun Wylie]]: codebreaker
* Tom Colvill: general manager

By the end of the war, the Testery had grown to nine cryptographers and 24 [[Auxiliary Territorial Service|ATS]] girls (as the women serving that role were then called), with a total staff of 118, organised in three shifts working round the clock.

==Surviving machines==
[[File:Lorenz SZ40 cipher machine (TUNNY) - National Cryptologic Museum - DSC07883.JPG|thumbnail|A Tunny (Lorenz) machine on display at the National Cryptologic Museum, Fort Meade, Maryland, USA]]
Lorenz cipher machines were built in small numbers; today only a handful survive in museums.

In Germany, examples may be seen at the [[Heinz Nixdorf MuseumsForum]], a computer museum in [[Paderborn]], and the [[Deutsches Museum]], a science and technology museum in Munich.<ref>{{cite web | url=http://www.deutsches-museum.de/en/exhibitions/communication/computers/cryptology/ | title=Cryptology | publisher=[[Deutsches Museum]] | access-date=30 October 2014}}</ref> Two further Lorenz machines are displayed at both [[Bletchley Park]] and [[The National Museum of Computing]] in the United Kingdom.  Another example is on display at the [[National Cryptologic Museum]] in Maryland, the United States.

John Whetter and John Pether, volunteers with The National Museum of Computing, bought a Lorenz teleprinter on [[eBay]] for £9.50 that had been retrieved from a garden shed in [[Southend-on-Sea]].<ref>{{Cite news |first=Paddy |last=O'Connell |date=29 May 2016 |title=Secret German WW2 Code Machine Found on eBay |url=https://www.bbc.com/news/uk-36401663 |publisher=[[BBC News]] |work=[[Broadcasting House (radio programme)|Broadcasting House]] |access-date=November 6, 2016}}</ref><ref>{{Cite news |first1=Damien |last1=Gayle |first2=James |last2=Meikle |date=29 May 2016 |title=Device Used in Nazi Coding Machine Found for Sale on eBay  |url=https://www.theguardian.com/technology/2016/may/29/nazi-coding-machine-lorenz-teleprinter-ebay |work=[[The Guardian]] |location=London |access-date=November 6, 2016}}</ref> It was found to be the World War II military version, was refurbished and in May 2016 installed next to the SZ42 machine in the museum's "Tunny" gallery.

==See also==
*[[Enigma machine]]
*[[Siemens and Halske T52]]
*[[Turingery]]
*[[Combined Cipher Machine]]

==Notes==
{{Reflist}}

==References==
* {{Citation | last = Churchhouse | first = Robert | title = Codes and Ciphers: Julius Caesar, the Enigma and the Internet | place = Cambridge | publisher = Cambridge University Press | year = 2002 | isbn = 978-0-521-00890-7 | url-access = registration | url = https://archive.org/details/codesciphersjuli0000chur }}
* {{Citation | editor-last = Copeland | editor-first = Jack | editor-link = Jack Copeland | title = Colossus: The Secrets of Bletchley Park's Codebreaking Computers | place = Oxford | publisher = Oxford University Press | year = 2006 | isbn = 978-0-19-284055-4 }}
* [[Donald W. Davies|Davies, Donald W.]], ''The Lorenz Cipher Machine SZ42'', (reprinted in ''Selections from Cryptologia: History, People, and Technology'', Artech House, Norwood, 1998)
* {{Citation | last = Flowers | first = Thomas H. | author-link = Tommy Flowers | title = Colossus | year = 2006 }} in {{Harvnb|Copeland|2006|pp=91–100}}
* {{Citation | last = Good | first = Jack | author-link = I. J. Good | year = 1993 | title = Enigma and Fish }} in {{Harvnb|Hinsley|Stripp|1993|pp=149–166}}
* {{Citation |last1=Good |first1=Jack |author-link=I. J. Good |last2=Michie |first2=Donald |author2-link=Donald Michie |last3=Timms |first3=Geoffrey |title=General Report on Tunny: With Emphasis on Statistical Methods |year=1945 |id=UK Public Record Office HW 25/4 and HW 25/5 |access-date=15 September 2010 |url=http://www.alanturing.net/turing_archive/archive/index/tunnyreportindex.html |archive-url= https://web.archive.org/web/20100917074406/http://www.alanturing.net/turing_archive/archive/index/tunnyreportindex.html |archive-date=17 September 2010 |url-status=dead}}. (Facsimile copy)
** {{Citation |last=Sale |first=Tony |author-link=Anthony Sale |title=Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale| year=2001 |url=http://www.codesandciphers.org.uk/documents/newman/newman.pdf |access-date=20 September 2010}}. (Transcript of much of this document in PDF format)
** {{Citation |last=Ellsbury |first=Graham |title=General Report on Tunny With Emphasis on Statistical Methods |url=http://www.ellsbury.com/tunny/tunny-001.htm |access-date=3 November 2010}}. (Web transcript of Part 1)
* {{Citation | last = Halton | first = Ken | title = The Tunny Machine | year = 1993 }} in {{Harvnb|Hinsley|Stripp|1993|pp=167–174}}
* {{Citation | editor-last = Hinsley | editor-first = F. H. | editor-link = Harry Hinsley | editor2-last = Stripp | editor2-first = Alan | year = 1993 | orig-year = 1992 | title = Codebreakers: The inside story of Bletchley Park | location = Oxford | publisher = Oxford University Press | isbn = 978-0-19-280132-6 }}
* {{ Citation | last = Hinsley | first = F. H. | author-link = Harry Hinsley | year = 1993 | title  = An introduction to Fish }} in {{Harvnb|Hinsley|Stripp|1993|pp=141–148}}
* {{Citation | last1 = Huttenhain |first1 = Orr |last2 = Fricke |title = OKW/Chi Cryptanalytic Research on Enigma, Hagelin and Cipher Teleprinter Messages |publisher = TICOM |year = 1945 |url = https://drive.google.com/file/d/0B7sNVKDp-yiJOWYxZWFmNDgtODUyMS00Y2FiLThkNWItYmQ5N2JmMzEyMzIz/view }}
* {{Citation | last = Klein | first = Melville | title = Securing Record Communication: The TSEC/KW-26 | url = http://www.nsa.gov/about/_files/cryptologic_heritage/publications/misc/tsec_kw26.pdf | access-date = 17 September 2010 | archive-url = https://web.archive.org/web/20120315235937/http://www.nsa.gov/about/_files/cryptologic_heritage/publications/misc/tsec_kw26.pdf | archive-date = 15 March 2012 | url-status = dead }}
* {{Citation | last = Parrish | first = Thomas | title = The Ultra Americans: The U.S. Role in Breaking the Nazi Codes | place = New York | publisher = Stein and Day | year = 1986 | isbn = 978-0-8128-3072-9 | url-access = registration | url = https://archive.org/details/ultraamericansth00parr }}
* {{Citation |last = Rezabek |first = Randy |title = TICOM: the Hunt for Hitler's Codebreakers |publisher = Independently published |year = 2017 |isbn = 978-1-5219-6902-1 |url = http://www.ticomarchive.com/home |access-date = 2021-01-16  |archive-date = 2022-05-26  |archive-url = https://web.archive.org/web/20220526090410/http://www.ticomarchive.com/home |url-status = dead }}
* {{Citation | last = Roberts | first = Jerry | author-link = Jerry Roberts | year = 2006 | title = Major Tester's Section }} in {{Harvnb|Copeland|2006|pp=249–259}}
* {{Citation | last = Roberts | first = Jerry | author-link = Jerry Roberts | year = 2009 | title = My Top-Secret Codebreaking During World War II: The Last British Survivor of Bletchley Park's Testery | url = http://www.ucl.ac.uk/news/news-articles/0903/09031601 | format = video | publisher = University College London }}
* {{Citation |last=Sale |first=Tony |author-link=Anthony Sale |title=The Lorenz Cipher and how Bletchley Park broke it |url=http://www.codesandciphers.org.uk/lorenz/fish.htm |access-date=21 October 2010}}
* {{Citation |last=Tutte |first=W. T. |author-link=W. T. Tutte |title=Fish and I |date=19 June 1998 |url= https://cryptocellar.web.cern.ch/cryptocellar/tutte.pdf |access-date=13 Feb 2015 |url-status=dead |archive-url= https://web.archive.org/web/20150212204111/https://cryptocellar.web.cern.ch/cryptocellar/tutte.pdf |archive-date=12 Feb 2015}} Transcript of a lecture given by Prof. Tutte at the [[University of Waterloo]]
* [http://www.alanturing.net/turing_archive/archive/b/B06/BO6-092.html Entry for "Tunny"] in the [[Government Code and Cypher School]] ''Cryptographic Dictionary''

==Further reading==
* {{Citation | last = Budiansky | first = Stephen | author-link = Stephen Budiansky | date = 2000 | title = Battle of wits: The Complete Story of Codebreaking in World War II | publisher = Free Press | isbn = 978-0684859323 | url-access = registration | url = https://archive.org/details/battleofwitscomp00budi }} Contains a short but informative section (pages 312–315) describing the operation of Tunny, and how it was attacked.
* {{Citation | last = Flowers | first = T. H. | author-link = Tommy Flowers | title = The Design of Colossus | journal = Annals of the History of Computing | volume = 5 | issue = 3 | pages = 239–252 | year = 1983 | url = http://www.ivorcatt.com/47c.htm | doi=10.1109/mahc.1983.10079| s2cid = 39816473 | url-access = subscription }}* Paul Gannon, ''Colossus: Bletchley Park's Greatest Secret'' (Atlantic Books, 2006). Using recently declassified material and dealing exclusively with the efforts to break into Tunny. Clears up many previous misconceptions about Fish traffic, the Lorenz cipher machine and Colossus.
* {{Citation | last = Small | first = Albert W. | title = The Special Fish Report | year = 1944 | url = http://www.codesandciphers.org.uk/documents/small/smallix.HTM | access-date = 21 September 2010 }}
* {{Citation | last = Smith | first = Michael | author-link = Michael Smith (newspaper reporter) | title = Station X: The Codebreakers of Bletchley Park | edition = Pan Books | series = Pan Grand Strategy Series | year = 2007 | orig-year = 1998 | publisher = Pan MacMillan Ltd | location = London | isbn = 978-0-330-41929-1 }} Contains a lengthy section (pages 148–164) about Tunny and the British attack on it.

==External links==
<!-- * [http://home.ecn.ab.ca/~jsavard/crypto/te0301.htm John Savard's page on the Lorenz machine]-->
* [http://www.cryptocellar.org/Lorenz/index.html Frode Weierud's CryptoCellar] Historical documents and publications about Lorenz ''Schlüsselzusatz'' SZ42. Retrieved 22 April 2016.
* [http://www.codesandciphers.org.uk/lorenz/index.htm Lorenz ciphers and the Colossus]
* [http://www.jproc.ca/crypto/tunny.html Photographs and description of Tunny]
* [http://www.cimt.plymouth.ac.uk/resources/codes/lorenz/default.htm Simplified Lorenz Cipher Toolkit]
* {{cite web|last1=Brailsford|first1=David|title=Fishy Codes: Bletchley's Other Secret|date=July 2015 |url=https://www.youtube.com/watch?v=Ou_9ntYRzzw |archive-url=https://ghostarchive.org/varchive/youtube/20211212/Ou_9ntYRzzw| archive-date=2021-12-12 |url-status=live|publisher=[[Brady Haran]]|access-date=10 July 2015|format=video}}{{cbignore}}
*[https://www.nsa.gov/public_info/_files/tech_journals/tunny_machine.pdf "Tunny" Machine and Its Solution] – [https://www.nsa.gov/about/cryptologic_heritage/60th/interactive_timeline/Content/1960s/media/19600901_Tiltman.pdf Brigadier General John Tiltman] – [https://www.nsa.gov/about/_files/cryptologic_heritage/publications/misc/tiltman.pdf National Security Agency]
*[http://www.ellsbury.com/tunny/tunny-000.htm General Report on Tunny: With Emphasis on Statistical Methods – National Archives UK]
*[http://www.alanturing.net/tunny_report/ General Report on Tunny: With Emphasis on Statistical Methods – Jack Good, Donald Michie, Geoffrey Timms – 1945]<!-- This report was classified until the middle of 2000, when it was released to the Public Record Office, Kew (document reference HW 25/4 and HW 25/5) -->.
* [https://lorenz.virtualcolossus.co.uk Virtual Lorenz 3D] A 3D browser based simulation of the Lorenz SZ40/42

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