Polyalphabetic Cipher C Program

By | November 18, 2017

Let us learn how to implement Polyalphabetic cipher in C programming with its algorithm, explanation, output and much more.

What is Polyalphabetic Cipher Algorithm?

A polyalphabetic cipher is a cipher based on substitution concept which uses multiple substitution alphabets.

Alberti Cipher is probably one of the initial ciphers invented by Leon Battista Alberti in around 1467. One of the popular implementations of this cipher algorithm is Vigenere cipher and Playfair cipher.

In this cipher algorithm, a cipher alphabet for the plain-text alphabet may be different at different places during the encryption process.

A popular cross-table called Tabula recta is used to identify elements for encryption and decryption based on Polyalphabetic Substitution Cipher algorithm.

Polyalphabetic Square Table To Encrypt and Decrypt in C Programming

The Polyalphabetic Cipher C program requires two inputs from the end user:

  • Plaintext
  • Key value


  • The polyalphabetic substitution is easy to implement
  • It makes frequency analysis more difficult.

Polyalphabetic Cipher Implementations

There are so many implementations of polyalphabetic substitution cipher algorithm enlisted below:

  1. Enigma cipher
  2. Beaufort cipher
  3. Vigenere cipher
  4. Autokey cipher
  5. Gronsfeld cipher
  6. Porta cipher
  7. Running key cipher

Polyalphabetic Cipher Encryption

Key Value: ABCD
Cipher Text: #PFLNH#OPIC

Polyalphabetic Cipher Decryption

Plaintext: #PFLNH#OPIC
Key Value: ABCD

Note: This encryption and decryption algorithm of Polyalphabetic Cipher in C programming is compiled with GNU GCC compiler using CodeLite IDE on Microsoft Windows 10 operating system.

C Program For Polyalphabetic Cipher Encryption


Implement Algorithm of Polyalphabetic Cipher in C Programming with Output

If you have any doubts about the implementation of Polyalphabetic Cipher in C programming, let us know about it in the comment section. Find more about it in Interactive Maths.

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3 thoughts on “Polyalphabetic Cipher C Program

  1. Mark Weins

    What is frequency analysis used in polyalphabetic cipher algorithm for?

    1. Tushar Soni Post author

      Frequency analysis is the practice of
      decrypting a message by counting the frequency of ciphertext letters, and equating it to the letter frequency of normal text.


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