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Saturday, November 16, 2013

History of Computer Science: Cryptography Before Digital Computers

The beginning of cryptography was when humans spoke their first words. Even to this day a language can be considered a form of cryptography because if you don’t know the language another person is speaking you will have no idea what secrets they are talking about. This accounts for the use of written language as well since a majority of people, up until recently, were not able to read. Speaking and writing are easily breakable nowadays though. The Egyptian hieroglyphs could be considered a form of cryptography too as it used pictures to hide their stories. The first use of algorithms to secure a message was created by the Greeks who came up with the Spartan Scytale around 7th century B.C. Rods of different diameter were used to wrap a strip of parchment around it on which a message was written. The Caesar Cipher appeared during, you guessed it, Julius Caesar’s rule and was used for war (as was the Scytale). The Caesar Cipher, a monoalphabetic cipher, used simple substitution as a form of confusion. There was little advancement in cryptography until the Middle Ages but the Arabs did make headway in cryptoanalysis by using frequency analysis.



                In the 1500’s, Leon Battista Alberi, “The Father of Western Cryptology,” developed polyalphabetic substitution. Polyalphabetic uses multiple alphabets to hide the plaintext by allowing different ciphertext symbols to represent the same plaintext symbol. During the 16th century, Blaise de Vigènere made improvements to polyalphabetic substitution which was used until the Civil War. Around WWI codebook ciphers and the one-time pad showed up. The one-time pad was started by Gilbert Vernam and improved by Joseph Mauborgne. In the case of the one-time pad, if the key is truly random and used only once then it provides perfect secrecy. Arthur Scheribus invented the Enigma machine at the end of WWI, it was used commercially at first and then improved by the German government for use in WWII. The machine was broken by a Polish cryptologist, Marian Rejewksi, and his work was transferred over to Alan Turing and the code breakers at Bletchley Park to build Bombes which were electromechanical machines that were designed specifically to break Enigma.

More detailed history here and here.

More info on different cryptography systems here.

1 comment:

  1. Sander, your post was very informational. Indeed, when we think about it, language is another type cryptography. It still is today. I think that it is interesting how many of cryptography was born and use for war. This shows how powerful information can be. With the correct information, war can be overturn. Today, information is still a powerful thing, and cryptography still exists within our computer today. An example of this is the encryption of password to keep is secure from any hackers.

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