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CRYPTOGRAPHY

Presented by Kinley

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History of CryptographyIn the beginning: before 2000 BC

Before 2,000 BC

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Around 1900 BC : In Egypt [Non-Standard hieroglyphics]

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Greeks and Spartans used this cipher to communicate during military campaigns

Called Transposition Cipher

487 BC: The Greek used a device called the Scytale

http://flylib.com/books/2/827/1/html/2/images/1004.jpg

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200–118 BC: Another Greek method was developed by Polybius (now called the "Polybius Square").

I A M A T T A C K E D42 1123 23 44 44 11 31 52 51 41

I A M ATTACKED = 42 1123 23 44 44113152 5141

http://www.sciencephoto.com/image/363640/530wm/V4000161-Polybius_square-SPL.jpg

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60-50 BC: Caesar Shift Cipher

Encrypt (“BAD”, 3) = “EDG” Decrypt (“EDG”, 3) = “BAD”

Julius Caesar used it to communicate with his generals during his military campaigns.

It is also used to secure secret communications from military leaders, diplomats, spies and religious groups

Called Mono-alphabetic Substitution Ciphers

http://www.secretcodebreaker.com/ciphrdsk.gif

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The Breaking Caesar Shift Ciphers The algorithm was not particularly strong

Using Frequency Analysis

In English (Source: Beker & Piper)

VIDEO CLIP

15th Century: Leon Battista Alberti

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http://www.cs.trincoll.edu/~crypto/historical/alberti.jpg

http://upload.wikimedia.org/wikipedia/commons/thumb/7/70/Alberti_cipher_disk.JPG/250px-Alberti_cipher_disk.JPG

Leon Battista Alberti (1404–1472) was an Italian author, artist, architect, poet, priest, linguist, philosopher and general Renaissance polymath. Being an accomplished cryptographer, Hepublished the earliest book on cryptanalysis in western Europe,created the first polyalphabetic cipher (now known as the Alberti cipher) invented the first encryption machine (the Alberti Cipher Disk).

His polyalphabetic cipher was the most significant advance in cryptography since Julius Caesar's time. He is known as “Father of Western Cryptography."

Frequency Analysis:The relative frequency of letters used in the English language. 'E' is the most commonly used letter, followed by 'T', 'A', 'O' and 'I' respectively.

Encryption using single key in Alberti Cipher Disk

Its consisted of two metal discs, one mobile, and one immobile, attached by a common axle so that the inner disc may be rotated

Encryption using Multiple keys in Alberti Cipher Disk

It was known as "unbreakable cipher” based on frequency analysis

http://www.geocaching.com/seek/cache_details.aspx?guid=1b622946-92f8-4fad-a009-ce83b88791f2

America's minister to France The wheel cipher consisted

of a row of cylindrical wooden pieces, each threaded onto an iron spindle.

The letters of the alphabet were inscribed on the edge of each wheel in a random order.

Turning these wheels, words could be scrambled and unscrambled.

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1790: Thomas Jefferson invented Wheel cipher.

http://www.cryptologicfoundation.org/content/A-Museum-Like-No-Other/images/m94_005.jpgExample:

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19th Century: Blaise de Vigenère was a French diplomat with Roman and cryptographer

• The Vigenère cipher is a method of encrypting alphabetic text by using a series of different Caesar ciphers based on the letters of a keyword

• Vigenere’s polyalphabetic cipher generalizes Caesar’s shift cipher and called Vigenere polyalphabetic Cipher

• Known as “The Unbreakable Cipher” until Charles Babage developed the Multiple frequency Analysis and Friedrich Kasiski, the Prussian military officer analyzes repetitions in the ciphertext to determine the exact period and he is credited with breaking the Vigenère cipher in 1863

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A A B C D E F G H I J K L M N O P Q R S T U V W X Y ZB B C D E F G H I J K L M N O P Q R S T U V W X Y Z AC C D E F G H I J K L M N O P Q R S T U V W X Y Z A BD D E F G H I J K L M N O P Q R S T U V W X Y Z A B CE E F G H I J K L M N O P Q R S T U V W X Y Z A B C DF F G H I J K L M N O P Q R S T U V W X Y Z A B C D EG G H I J K L M N O P Q R S T U V W X Y Z A B C D E FH H I J K L M N O P Q R S T U V W X Y Z A B C D E F GI I J K L M N O P Q R S T U V W X Y Z A B C D E F G HJ J K L M N O P Q R S T U V W X Y Z A B C D E F G H IK K L M N O P Q R S T U V W X Y Z A B C D E F G H I JL L M N O P Q R S T U V W X Y Z A B C D E F G H I J KM M N O P Q R S T U V W X Y Z A B C D E F G H I J K LN N O P Q R S T U V W X Y Z A B C D E F G H I J K L MO O P Q R S T U V W X Y Z A B C D E F G H I J K L M NP P Q R S T U V W X Y Z A B C D E F G H I J K L M N OQ Q R S T U V W X Y Z A B C D E F G H I J K L M N O PR R S T U V W X Y Z A B C D E F G H I J K L M N O P SS S T U V W X Y Z A B C D E F G H I J K L M N O P Q RT T U V W X Y Z A B C D E F G H I J K L M N O P Q R SU U V W X Y Z A B C D E F G H I J K L M N O P Q R S TV V W X Y Z A B C D E F G H I J K L M N O P Q R S T UW W X Y Z A B C D E F G H I J K L M N O P Q R S T U VX X Y Z A B C D E F G H I J K L M N O P Q R S T U V WY Y Z A B C D E F G H I J K L M N O P Q R S T U V W XZ Z A B C D E F G H I J K L M N O P Q R S T U V W X Y

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Example:

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1917 Century; Gilbert Vernam was an engineer for The American Telephone and Telegraph Company. He was asked in 1917, during WWI, to develop a teletypewriter that encrypted transatlantic telegraph messages sent by the War Department to United States troop commanders in Europe. Vernam Cipher used a random key to encrypt the message sent by telegraph printer known as Vernam Cipher which was the first example of online encryption.The system, which was modified by the Army Signal Corps, was later proved to be unbreakable by using a different key every time a message was sent. This was called One Time Pad Cipher.

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http://people.rit.edu/japnce/payne/images/vernamcipherdevice1.gif

Enigma Machine

Electro-mechanical cipher machine, simple in design yet powerful in capability

Built in Germany in 1918 at the end of WWI and later adapted for commercial use, and by German military in 1926

Uses rotors settings (the key) to encrypt each letter of a message with a different cipher key

Military added the plugboard to commercial Enigma, greatly increasing cryptologic strength

Strength of Enigma design gave Germans complete confidence in its security, even when faced with evidence of compromise

http://math.arizona.edu/~dsl/images/enigma11.gif

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1932-1944: The Pole, Marian Rejewski attacked and broke the early German Army Enigma system using theoretical mathematics in 1932. British code breakers designed Bombe to decrypt Enigma cipher machine Using Frequency analysis designed by Alan TuringIt was the greatest breakthrough in cryptanalysis in a thousand years and more http://math.arizona.edu/~dsl/images/enigma11.gif

Data Encryption Standard (DES) 1972: U.S. Government recognized the

need to have a standardized cipher for secret documents (encrypting classified and sensitive information)

NBS developed DES based on an earlier IBM algorithm, Horst Feistel's Lucifer cipher.

DES is a 64-bit block cipher algorithm (64-bit block = 56-bit secret key + 8-bit parity) that uses a key of 56 bits and 16 rounds of transposition and substitution to encrypt each group of 8 (64-bit) plaintext letters.

Horst Feistel was a German-born cryptographer who worked on the design of ciphers at IBM, initiating research that would culminate in the development of the Data Encryption Standard in the 1970s

http://cryptodox.com/images/thumb/d/d5/Feistel.jpg/180px-Feistel.jpg

Analysis of DES was the beginning of modern cryptographic research

Breaking of Data Encryption Standard (DES)

http://www.eff.org/Privacy/Crypto/Crypto_misc/DESCracker/

The key length of DES was too short• If a key is 56 bits long, that means

there are 256 possible keys• “DES Cracker” machines were

designed to simply brute force all possible keys

1977: DES-cracking machine was used Diffie and Hellman to find a DES key in a single day

1993: Wiener used a key-search machine to find a key within 7 hours

DES was further weakened by the discovery of differential cryptanalysis by Biham and Shamir in 1990 which requires 247 chosen plaintexts• Ideally a ciphertext should be completely

random, there should be no connection to its matching plaintext

• Differential analysis exploits the fact that this is never actually the case

• Uses patterns between plaintext and ciphertext to discover the key

There is evidence that IBM knew about differential cryptanalysis back when they were designing DES in 1976

Advanced Encryption Standard

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The U.S. government approved AES for protecting secret and top secret classified documents.

This is the first time the United States has ever approved use of a commercial algorithm derived outside the government to encrypt classified data.

With DES effectively broken, a new standard was needed

U.S. Government made it an open application/review process this time, and received many submissions

In 2001, after five years, Belgian cryptographers, Joan Daeman and Vincent Rijman’s Rijndael algorithm was selected by NIST become as the Advanced Encryption Standard (AES).

AES is a symmetric block cipher that can… Process data blocks of 128 bits. Uses cipher keys with lengths of 128, 192,

and 256 bits. Variable number of rounds, each round

10, 12, or 14 rounds depending on the key size

Current attacks against AES On AES with 128-bit keys, a brute force attack would require 2128

work Any technique that can decrypt a ciphertext with less than 2128 work is

considered an attack Currently the best attacks on AES use variations of differential

cryptanalysis None of them could actually be completed before the sun burns out None of them work on the full number of rounds

Video Clips

1976: Whitfield Diffie & Martin Hellman published New Directions in Cryptography.

Develop the fundamental ideas of dual-key, or public key, cryptography solving one of the fundamental problems of cryptography, key distribution

We use one key for encryption (the public key), and a different key for decryption (the private key)

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diffie.jpg

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1978: Ronald L. Rivest, Adi Shamir & Leonard M. Adleman (RSA) published RSA Algorithm for Public Key System.

The RSA algorithm was publicly described in 1977 but was never deployed. It was not revealed until 1998 due to its top-secret classification

RSA was based on product of two large prime numbers

Uses this product to create the public and private keys

Sends the product and the public key one, who can use them to encrypt messages

Even if some one knows the product and the public key, he/she can’t figure out the private key unless he/ she can factor the productThere is no known way to do this efficiently

Keys: 1,024 to 4,096 bit typical

http://datanews.levif.be/ict/actualite/apercu/2011/02/17/un-lifetime-achievement-award-pour-les-pionniers-de-rsa/article-1194952831693.htm

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Cryptography in Modern Living Secure Communications

-Document / Data / Email Encryption

Identification and Authentication-Smart Cards

Electronic Commerce and Payments –ATMs / Credit Cards–Net Banking / Web Shopping

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References Boone, J.V. (2005). A Brief History of Cryptology. Naval Institute Press, USA Damico,Tony M. (2009), A brief history of cryptography. Retrieved June 31, 2012,

http://www.studentpulse.com/articles/41/a-brief-history-of-cryptography Denning, Dorothy E. (1982). Cryptography and Data Security. Addison-Wesley Publishing

Company, Inc. Canada Macgregor, Mary. The Story of Greece [on-line]. Available: http://www.heritage-

history.com/www/heritage-books.php?Dir=books&author=macgregor&book=greece&story=head

Mackenzie, Dana (2003). The Code War. An article was provided by the National Academy of Sciences. NW, Washington

Pell, Oliver ().Cryptology. Retrieved July 18 2012, http://www.ridex.co.uk/cryptology Pfleeger, C.P & Pfleeger, S. L (2007). Security in Computing. Pearson education Inc. NJ,

USA Servos, William (2006). Cryptography. Retrieved July 18 2012,

http://www.cs.trincoll.edu/~crypto/historical/alberti.html Shannon, C. E. Communication Theory of Secrecy Systems. Retrieved 19 July 2012,

http://netlab.cs.ucla.edu/wiki/files/shannon1949.pdf Singh, Simon (1999). The Code Book. Doubleday, USA. pp. 279-92 Wardlaw, W.P. The RSA Public key cryptosystem. Mathematics department, U.S naval

academy, Annapolis. Retrieved 19 July 2012, http://www.usna.edu/Users/math/wdj/papers/cryptoday/wardlaw_rsa.pdf

Paremes Laosinchai, Ph.D

Plain Text: "The package is in the drop zone."

Example of Wheel Cipher Encryption

Rotate the individual disks until we spelled out that message as shown.

Encrypted Message: “EVAOSWMNDTKERXSKNKSEYFEEWS”

Example of Vigenère Cipher Plain Text:

ATTACKATDAWN

Key: LEMON

Plain text: ATTACKATDAWN

Key: LEMONLEMONLE

Cipher text: LXFOPVEFRNHR

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1930-1941: In WWII, German military used Lorenz SZ 40 and SZ 42 cipher machines based on Vernam cipher to encrypt tele-printer messages. To break the enormous amount of encrypted message traffic the code breaker had to build new, automated machines, which lead directly to the development of the first digital computers. This was the first step in the evolution of cryptography towards the new computer age.

1943-1944: British code breakers designed Colossus Mark 1 and Colossus Mark 2 to decrypt Lorenz cipher machine using frequency analysisDesigned by Max Newman & Tommy Flowers

http://blogs.guardian.co.uk/technology/Colossus_back_(800%20x%20600).jpg

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What is Cryptography?

Secret Writing

Steganography(hidden)

Cryptography(scrambled)

Substitution

Transposition

Code(replace words)

Cipher(replace letters)

CRYPTOLOGY

Breaking of codes and cipher

Cryptanalysis

Cryptographic Algorithm & Operation

Message RecipientMessage Sender

Secret key

Crypto-system

Encryption

Plaintext Ciphertext

Crypto-system

Decryption

PlaintextCiphertext

EK(M) = C DK(C) = M