Crypto - A Fascinating History by Atul Kahate

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Atul Kahate

www.atulkahate.com / akahate@gmail.com

Cryptography – A Fascinating
History

Atul Kahate


Three people can keep a secret if …
… two of them are dead

Crypto - A Fascinating History | Atul Kahate 3

Basic Principles

Substitution

Transposition


Persia Versus Greece (5th Century BC)

Wooden tables – Scratch the lower part, write
messages, cover with wax


Greeks and Waxing of Secret Messages

Secret messages would be written as tattoos
into the shaven heads of messengers


Steganography

Steganos = Covered, graphein = writing in
Greek


Julius Caesar (100 BC-44 BC)


Queen Mary of Scotland (1542-1587) and
Queen Elizabeth I of England (1533-1603)


Early Chinese Methods

Write messages on fine silk and put that in a
tiny ball covered with wax – messenger
would swallo it
Write in invisible ink
Cryptography
Kryptos = Hidden in Greek
Aim is not to hide the fact that there is a message,
but the contents of a message


Leon Battista Alberti (1404-1472) –
Painter, Composer, Poet, Philosopher, Author


Blaise de Vigenere (1523-1596) – French
diplomat and cryptographer – See next slide


Vigenere Square Example

1. Draw a Vigenere square (previous slide)
2. Top row represents the plain text letter and
columns indicate key – look for the cross-section
3. Replace it with the cipher text letter from the
square based on the key
Example: Message is divert troops and key is white
then encryption would be:
Key : w h i t e w
Plaintext : d I v e r t
Ciphertext : z p d x v p


Charles Babbage (1791-1871) – Broke Vigenere
Cipher … Difference and Analytical Engines


Lovers and Newspapers

Encrypted messages to each other via
personal columns in the newspapers – called
as agony columns
Babbage along with his friend Charles
Wheatstone
Oxford student incident involving Wheatstone in
The Times
Newspapers were posted for free in those
days – people would use pinpricks to secretly
add messages


USA – Independence Struggle (1770s)

Benjamin Church George Washington


Telegraph – More need for Secrecy! – Morse
(1791-1872) and Wheatstone (1802-1875)


Wireless! – Galvini, Volta, Orsted, Faraday,
Ampere, Henry, Maxwell, Lodge …


Wireless! – Hertz, Marconi


First World War

1917 – Germany, Planned attack on British
naval base, Fear of attacking American ships
by mistake, German Foreign Minister Arthur
Zimmermann planned to forge an alliance
with Mexico to help recapture lost territory


The Famous Telegram


Enigma

1918 – Scherbius & Ritter - Company formed
by German inventor Arthur Scherbius and his
friend Richard Ritter


Hans-Thilo Schmidt (1888-1943)

German soldier in The First World War,
Rejected in the Second one, disgruntled,
Soap factory failure, Hyperinflation, Elder
brother Rudolph in Army authorized Enigma,
Further anger, Sold Enigma papers for
10,000 Marks


Breaking Enigma in the Second World
War – Marian Rejewski (1905-1980)
Polish mathematician – Timid – Fled to
England after Germany attacked Poland –
1932 – Started working on breaking Enigma


Bletchley Park – Alan Turing (1912-1954)


Navajo Code Talkers


DES – 1975

Horst Fiestel (1915-1990) and Lucifer


Public Key Cryptography - Whitfield Diffie
(1944 -) and Martin Hellman (1945 -)

With Merkel here


RSA

Ron Rivest (1947 -), Adi Shamir (1952 -), and Len Adleman
(1945 -)


Jim Bidzos


Secure Email – Phil Zimmerman


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Thank You Very Much!

Any Questions or Comments?


Crypto - A Fascinating History by Atul Kahate

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