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Cryptography

Cryptography. Methods of Encryption. Transposition Switching the symbols within the plaintext Substitution Substituting different symbols for the symbols in the plaintext. Transposition. Rail fence cipher: one if by land two if by sea - plaintext o e f y a d w i b s a

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Cryptography

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  1. Cryptography

  2. Methods of Encryption • Transposition • Switching the symbols within the plaintext • Substitution • Substituting different symbols for the symbols in the plaintext

  3. Transposition • Rail fence cipher: one if by land two if by sea - plaintext o e f y a d w i b s a n i b l n t o f y e oefyadwibsaniblntofye - ciphertext

  4. Substitution • Julius Caesar Cipher • Substitute each letter in the plaintext by the letter that is 3 down from it. • Encode(letter)=(letter+3) mod 26 • Decode(letter)=(letter -3) mod 26

  5. Caesar Cipher example • Plaintext: One if by land two if by sea • Ciphertext: Rqh li eb odqg wzr li eb vhd

  6. Caesar Cipher Example • Decode the following message: vhqg pruh slccd

  7. Caesar Cipher Example • Decode the following message: vhqg pruh slccd • Answer: send more pizza

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