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CIS 115

Lecture 9: Cryptography

Message to the Class

TSTEPHAAXLISLAESCEMQIYQ

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:

Chaocipher

Chaocipher Device

Image Source: Cryptologicfoundation.org