Playfair Cipher in C (Encryption & Decryption)

The Playfair cipher or Playfair square or Wheatstone-Playfair cipher is a manual symmetric encryption technique. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair for promoting its use.

The Playfair cipher uses a 5 by 5 table containing a key word or phrase. Memorization of the keyword and 4 simple rules was all that was required to create the 5 by 5 table and use the cipher.

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Monoalphabetic Cipher in C (Encryption & Decryption)

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Caesar Cipher in C (Encryption & Decryption)

Caesar cipher, also known as Caesar's cipher, the shift cipher, Caesar's code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plain text is replaced by a letter some fixed number of positions down the alphabet.

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