History of CryptographyAdam GoodbarClemson UniversityApril, 2007

Origins of Cryptography

•Thought that the earliest form of cryptography was in the Egyptian town of Menet Khufu

•The hieroglyphics on the tomb of nobleman KHNUMHOTEP II contained unusual symbols, used to obscure the meaning of the inscriptions.

Origins of Cryptography• The Spartans, in 5 BC,

developed a device called a Scytale.

• A messenger would carry a strip of parchment, which was meaningless until it was wrapped around a Scytale of the same dyameter.

• Was a type of Transposition Cypher.

Origins of Cryptography

•Caesar Shift Cipher▫Each letter was substituted by shifting n

places▫Only 25 possible ciphers.

•Substitution Based on Key Phrase▫Key consists of Phrases Letters (Unique),

followed by the rest of the alphabet. THIS IS ALICE AND BOB’S KEY THISALCENDBOKY-FGJMPQRUVWXZ

▫26! Possible ciphers.

Cryptanalysis and World War I - The Zimmermann Telegram• The Telegram from

Germany, to Mexico, proposed a German supported offensive by Mexico on the United States, if the US should attack Germany and become involved in WWI.

• The breaking of this telegram by “Room 40” of British Naval Intelligence, and the passing of the telegram to the US, helped prompt the US’s entry into World War I.

GCHQ

•During WWI, the British Army had a separate SIGINT division from the British Navy.

•The Navy’s SIGINT division was the famous “Room 40”, or NID25

•After WWI, it was proposed that a peacetime codebreaking division be created

•The Government Communications Headquarters was created

GCHQ•Based out of Bletchley Park, and famous for

breaking German Enigma codes.•Pre WWII, was a very small department.•By 1940, was attacking codes of 26 countries

and over 150 diplomatic cryptosystems

•Discussed in Neal Stephenson’s Cryptonomicon▫Great Book! Takes many historical liberties

however.

World War II Cryptography• Most Famous example of

Cryptography in World War II was the German Enigma.

• Made use of Rotors and Plugboards

• One or more of the rotors moved after each key press, depending on the settings.

• Created a changing substitution cypher, or a polyalphabetic substitution cypher.

Cryptanalysis and World War II - • Britain used the term “Ultra” to describe

intelligence from the cryptanalysis, specifically resulting from Enigmas.

• “Britain's top military officers were told they must never reveal that the German Enigma code had been broken because it would give the defeated enemy the chance to say they ‘were not well and fairly beaten’” by Gp Capt Winterbotham

• Gp Capt Winterbotham was the first to break this rule, in 1974.

Current Day Cryptography - Diffie-Hellman key exchange•Produced by Whitfield Diffie and Martin

Hellman in 1976•Later discovered that a similar method

had been developed by the GCHQ (The British SIGINT agency), in 1973, but was kept classified until 1997

•D-H developed the method independently.

Whitfield Diffie• Received a BS from MIT in

1965, and awarded a Doctorate in Technical Sciences (Honoris Causa) from the Swiss Federal Institute of Technology in 1992

• Joined Sun Microsystems in 1991, as a Distinguished Engineer.

• Currently still a Sun employee, serving as VP, Sun Fellow, and Chief Security Officer

Martin Hellman• Earned his Bachelors of

Science from New York University in 1966, and a Masters in 1967 and PhD in 1969 from Stanford University, in Electrical Engineering.

• Assistant Professor at MIT from 1969 – 1971

• Became a Stanford Professor in 1971, until 1966, when he became Professor Emeritus

Current day Cryptography – RSA Encryption•Developed by Ron Rivest, Adi Shamir, and

Leonard Adleman•Type of Public Key Encryption•Later discovered that a similar method

had been developed by the GCHQ (The British SIGINT agency), in 1973, but was kept classified until 1997

Ron Rivest• Earned a BS in

Mathematics from Yale in 1969, and a Ph. D in Computer Science from Stanford University in 1974.

• Also authored RC2, RC4, RC5, and co-invented RC6

• Author of MD2, MD4, and M5 Cryptographic Hash Functions

ThreeBallot• The System has two goals:

▫“Have voter's votes be "secret ballot" – so that nobody can know how anyone voted (not even if the voter wants to tell them) and hence nobody could bribe or coerce you to vote some way, and you could not sell your vote.”

▫“Have the election be secure and verifiable – so that we could all be confident that nobody voted more than once, no votes were inserted, deleted, or altered, only authorized voters voted, and the results were computed correctly from those votes.”

▫ (From RangeVoting.org)

ThreeBallot•“Trouble is, these two desires seem incompatible. It is trivial to get secure elections if the ballots are not secret; just publicize every voter-vote pair to make it trivial to verify that everybody voted as they said they did (or didn't) and the ballots were tallied correctly. But then it'd also be trivial to coerce voters, rather undermining "democracy.”” (From RangeVoting.org)

• Immediately put in the Public Domain by Rivest.

ThreeBallot

•From Website:▫Coercer: "I demand you vote AGAINST Bush.

And bring me a receipt saying 'AGAINST BUSH' on it."

▫You: Yes, boss!▫Coercer: Very good. But wait, how do I know

you did not also vote FOR Bush twice (and also both FOR and AGAINST Nader) and thus in total really voted for Bush?

▫You: You don't.▫Coercer: (foiled again).

Adi Shamir• Received a BS in

Mathematics from Tel Aviv University in 1973.

• MS and Ph.D from the Weizmann Institute in 1975/1977

• Researched at MIT from 1977 – 1980.

• Then returned as a faculty member at the Weizmann Institute

• Discovered Differential Cryptanalysis, used for attacking Block Cyphers

Leonard Adleman• Attended UC Berkley,

receiving his BA in Mathematics in 1968, and then his Ph.D in EECS 1976.

• Heavy research in DNA computing.

• Published a paper in 1994, entitled “Molecular Computation of Solutions To Combinatorial Problems”

• Solved a 7 node Hamiltonian graph using DNA computation

Current day Cryptography –DES• Symmetric Key Algorithm.• DES Uses a 56-bit key, so 256 possible keys.• Over 72 quadrillion keys!• Even with all these keys, still susceptible to

brute force attacks.• “It is known that the NSA encouraged, if not

persuaded, IBM to reduce the key size from 128 to 64 bits, and from there to 56 bits; this is often taken as an indication that the NSA possessed enough computer power to break keys of this length even in the mid-1970s.” (Wikipedia)

Deep Crack• Built in 1998, for a cost of

$250,000• Able to brute force a key

within a day.• Used to win RSA’s

Security DES Challenge III

COPACOBANA(Cost-Optimized PArallel COde Breaker)Cost of $10,000 120 FPGA Processors on 20

DIMM modules

References• “Ron Rivest's "3ballot" scheme for cryptographically-secure

voting – without cryptography! – and the "BOFFO" plan”, Warren D. Smith, http://rangevoting.org/Rivest3B.html

• http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2006/06/22/nenigma22.xml&sSheet=/news/2006/06/22/ixuknews.html

• Wikipedia (As a starting point )• http://www.cypher.com.au/crypto_history.htm