A Glimpse of t he Hist ory of Crypt ography Cunsheng Ding Depar t - - PowerPoint PPT Presentation

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A Glimpse of t he Hist ory of Crypt ography

Cunsheng Ding Depar t ment of Comput er Science HKUST, Hong Kong, CHI NA

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P art I I : Machine Ciphers

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Enigma

• Bef ore war broke out in

1939 t he Germans had planned a special way of keeping t heir communicat ions secr et . The army, navy and air f orce wer e t old t o encode t heir messages using cipher machines called ENI GMA.

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Enigma

• Enigma could put a message int o

code in over 150 MI LLI ON MI LLI ON MI LLI ON dif f erent ways.

• The Germans believed t hat no
• ne could crack t he Enigma code.

But t he Allies knew t hat if t hey could, t hey would be able t o f ind

• ut t heir enemy' s milit ary

secr et s.

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Enigma

• The Enigma machine looked

like a t ypewrit er in a wooden

• box. An elect ric current

went f r om t he keyboar d t hrough a set of rot ors and a plugboard t o light up t he ' code' alphabet .

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Enigma

• At least once a day t he

Ger mans changed t he or der

• f t he rot ors, t heir st art ing

posit ions and t he plugboard connect ions. To decipher a message sent using Enigma, you had t o wor k out exact ly how all of t hese had been set .

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Enigma

• I n t he 1930' s Polish cipher

exper t s secr et ly began t o t ry t o crack t he code. J ust bef or e war br oke out t hey managed t o pass models and dr awings of Enigma t o Br it ish and Fr ench code- breakers.

• Lat er Enigma was br oken.

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Sigaba

• I t was suit ed f or

f ixed st at ion secure communicat ions, and used by U.S. f or high- level communicat ions, was t he only machine syst em used by any part icipant t o remain complet ely unbroken by an enemy during World War I I .

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B-21 Machine by Boris Hagelin

• Pat t erned on t he

Enigma and produced f or t he Swedish General st af f , Boris Hagelin of Sweden developed t he B-21 machine in 1925. I t also had t he capabilit y t o be connect ed t o an elect ric t ypewrit er.

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BC-38 by Crypt o AG Zug

• Boris Hagelin of

Sweden developed a long line of cipher syst ems, beginning wit h t he B-21, B- 211, C-35, C-36, C- 38 (which lat er became Amer ica' s M-209).

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BI D 590 (Noreen)

• The BI D 590 was a

Brit ish built crypt o machine and was used by Canada' s f oreign service communicat ors at various diplomat ic missions t o communicat e wit h various government depart ment s.

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H-4605 (Crypt o AG)

• The Crypt o AG H4605

was designed as an

• f f -line, keyboar d
• perat ed cipher

machine wit h t win print ing (of cipher and plain t ext ) syst em wit h aut omat ic 5-let t er

• grouping. I t ' s a solid

piece of equipment , almost ' bat t leship grade’.

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J apanese "Enigma" Rot or Cipher Machine

Produced by Germans for Japanese

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Japanese Purple machine

♦ Electromechanical stepping switch machine

modelled after Enigma

♦ Used telephone stepping switches instead of rotors ♦ Purple was broken with the help of MAGIC. ♦ Pearl Harbor attack preparations encoded in

Purple, decoded hours before attack.

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KY-28 (Nest or)

• The KY-28 was an

analog, voice encr ypt ion device based on t ransist or cir cuit r y and was t he shipboar d/ air bor ne member of t he NESTOR f amily of equipment .

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Racal-Milgo 64-1027C Dat acrypt or

• The Racal-Milgo 64-

1027C Dat acrypt or was used t o send and receive secure dat a via comput er. This is t he commercial version of t he KG-84, and has abilit y t o be loaded via t he KYK-13 Fill device.

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The “Clock Crypt ograph”

• I t is basically a

nicely implement ed Wheat st one cipher

• disk. I t was in

act ive use in t he Danish ar med f or ces f r om 1934 (or a lit t le earlier) unt il ar ound 1948.

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People in Breaking Codes

• Blet chley Par k was

t he home of t he secr et Gover nment Code and Cypher

• School. This was t he

cent re of Brit ish code-br eaking dur ing t he war.

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People in Breaking Codes

• The code-breakers in Blet chley

P ark were specially chosen f rom among t he cleverest people in

• England. Some were brilliant

mat hemat icians or linguist s.

• Alan Turing, a Cambridge

mat hemat ician and code-breaker who helped t o invent one of t he world' s f irst comput ers at Blet chley Park.

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Comput er and Code Breaking

• Colossus was built

f or t he code- br eaker s at Blet chley Par k by post of f ice engineer s in 1943.

• One of t he earliest

comput er s.

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Comput er and Code Breaking

• The comput er was as

big as a room - 5 met res long, 3 met res deep and 2.5 met res high - and was made mainly f r om par t s used f or post of f ice t elephone and t elegr aph syst ems.

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Comput er and Code Breaking

• This Cray XMP was

donat ed t o t he museum by Cray Research, I nc. I t denot es t he newest era of part nership bet ween NSA and t he American comput er indust ry in t he employment of comput ers f or crypt ologic processes.