Crypto Corner
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    • Glossary
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  • Introduction to Cryptography
    • Steganography
    • Codes and Ciphers
    • Conventions in Cryptography
  • Monoalphabetic Substitution Ciphers
    • Atbash Cipher
    • Pigpen Cipher
    • Caesar Shift Cipher
    • Affine Cipher
    • Mixed Alphabet Cipher
    • Other Examples
    • Frequency Analysis: Breaking the Code
    • Homophonic Substitution
  • Simple Transposition Ciphers
    • Rail Fence Cipher
    • Route Cipher
    • Columnar Transposition Cipher
    • Myszkowski Transposition Cipher
    • Permutation Cipher
    • Anagramming: Jumbling words
    • Combining Monoalphabetic and Simple Transposition Ciphers
  • Polyalphabetic Substitution Ciphers
    • Vigenère Cipher
    • Kasiski Analysis: Breaking the Code
    • Autokey Cipher
    • Other Examples
  • Fractionating Ciphers
    • Polybius Square
    • Straddling Checkerboard
    • Transposing Fractionated Text
    • Other ways to Alter Fractionated Text
  • Digraph Substitution Ciphers
    • Playfair Cipher
    • Two-Square Cipher
    • Four-Square Cipher
    • Hill Cipher

Conventions in Cryptography

Throughout the site various cryptgraphic conventions will be used, which are explained here.

  • The plaintext is the message that is being encrypted by the sender of the message, and will be written in lowercase letters, and surounded by quotation marks.
  • The ciphertext is the encrypted message that is actually sent to the recipient to be decrypted, and will be written using uppercase letters, and surounded by quotation marks.
  • An intercept is a piece of encrypted text that has been discovered by an interceptor. That is, it is a ciphertext when you do not know the cipher used.
  • Most ciphers use a key to make the encryption unique and hence more secure. The key usually takes the form of either a number or a word, and it always changes the more general algorithm for the encryption in some way. By using a key, the sender is trying to make the plaintext irretrievable should the ciphertext fall into the hands of an interceptor who does not know the key, even if they know which cipher has been used. This is at the very heart of cryptography, and is known as Kerckhoffs's Principle (or Shannon's Maxim). The key will always be written in lowercase, and in italics.
  • The alphabet used in the encryption process can make a big difference to the ciphertext. It consists of the letters and symbols which will be transformed by the cipher. More importantly, any symbol which is NOT in the alphabet will be left unaltered in the ciphertext. The standard alphabet we shall use is the 26 Roman Letters "abcdefghijklmnopqrstuvwxyz". This means that any spaces, punctuation marks or numbers will not be changed in the ciphertext. Other alphabets can also be used containing these extra characters, and examples will be given for the more simple ciphers using these.


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  • Home
    • Crypto Corner Challenges
    • Glossary
    • Help with Activities
    • Educational Uses
    • Downloadable Resources
  • Introduction to Cryptography
    • Steganography
    • Codes and Ciphers
    • Conventions in Cryptography
  • Monoalphabetic Substitution Ciphers
    • Atbash Cipher
    • Pigpen Cipher
    • Caesar Shift Cipher
    • Affine Cipher
    • Mixed Alphabet Cipher
    • Other Examples
    • Frequency Analysis: Breaking the Code
    • Homophonic Substitution
  • Simple Transposition Ciphers
    • Rail Fence Cipher
    • Route Cipher
    • Columnar Transposition Cipher
    • Myszkowski Transposition Cipher
    • Permutation Cipher
    • Anagramming: Jumbling words
    • Combining Monoalphabetic and Simple Transposition Ciphers
  • Polyalphabetic Substitution Ciphers
    • Vigenère Cipher
    • Kasiski Analysis: Breaking the Code
    • Autokey Cipher
    • Other Examples
  • Fractionating Ciphers
    • Polybius Square
    • Straddling Checkerboard
    • Transposing Fractionated Text
    • Other ways to Alter Fractionated Text
  • Digraph Substitution Ciphers
    • Playfair Cipher
    • Two-Square Cipher
    • Four-Square Cipher
    • Hill Cipher