Cryptography

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Cryptography

• The Science of Secret Messages

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Secret Messages

• CODING ONE IF BY LAND, TWO IF BY SEA
• STEGANOGRAPHY A LOVELY ICING COVERED
  ÉCLAIR
• CRYPTOGRAPHY

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Terminology in Cryptography

• The PLAINTEXT is the message that will be put
  into secret form.
• The CIPHERTEXT is the message in secret form.
• The CIPHER ALPHABET is the set of symbols used
  for the ciphertext.

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• ENCIPHERMENT or ENCRYPTION is the process of
  transforming plaintext to ciphertext.
• DECIPHERMENT or DECRYPTION is the process of
  transforming ciphertext to plaintext.
• A KEY is an input component of the
  encryption/decryption process, along with the
  text.
• CRYPTANALYSIS is decipherment without posession
  of the key.

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Transposition Ciphers transpose the symbols in
the plaintext to produce the ciphertext.

• VENI, VIDI, VICI.

• C D E I I I I I N V V V

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Substitution Cipherssubstitute cipher alphabet
symbols for a letter or group of letters of the
plaintext

• VENI, VIDI,
  VICI.

• YHQL, YLGL,
  YLFL.
• VENI, VIDI, VICI.