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CIS 115
Lecture 9: Cryptography
Cryptography
Message to the Class
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Scytale
Image Source: Wikipedia
Message to the Class
TSTEPHAAXLISLAESCEMQIYQ
T H I S I
S A S C Y
T A L E Q
E X A M
P L E Q
Early Ciphers
Tabula Recta
Image Source: Wikipedia
Image Source: Wikipedia
Enigma Machine
Image Source: Wikipedia
Enigma Machine Rotors
Image Source: Wikipedia
Enigma Machine Rotors
Image Source: Wikipedia
Enigma Machine Ratchet
Image Source: Wikipedia
Image Source: Wikipedia
Enigma Machine Plugboard
Image Source: Wikipedia
Enigma Key
Enigma Operation
Enigma Stengths
Enigma Weaknesses
Marian Rejewski
Image Source: Wikipedia
Cracking Enigma
Bombe
Image Source: Wikipedia
Impact
“My own conclusion is that it shortened the war by not less than two years and probably by four years … we wouldn't in fact have been able to do the Normandy Landings, even if we had left the Mediterranean aside, until at the earliest 1946, probably a bit later.”
-Sir Harry Hinsley
British Intelligence Historian
Claude Shannon
Image Source: Wikipedia
Symmetric Key Encryption
Image Source: Wikipedia
Public Key Encryption
Image Source: Askamathematician.com
RSA Encryption
RSA Example
RSA Example
RSA Keys
Assignments
Blog 4: Cryptography
Many systems today depend on cryptography that is assumed to be unbreakable with modern technology. However, imagine a world where that was no longer the case. Each time you purchase something on the internet, there would no longer be anything preventing someone from intercepting your information. The same would apply to sites such as Facebook, GMail, and even your banking or medical information. Anything you store on a computer could be accessed by anyone that wants to get it. Write about how you think that would affect our perception of technology and how we use it in our daily lives. Some thoughts to ponder:
Scratch Chaocipher
Chaocipher
Chaocipher Device
Image Source: Cryptologicfoundation.org