Polyalphabetic Vigenere Cipher

Polyalphabetic cipher is a type of substitution cipher where each occurrence of a character may have a different substitute. That means that a single character in the plain text set may map to many characters in cipher text set. In polyalphabetic cipher, the cipher text is dependent on both, the corresponding plain text character, position of the plain text in the character and the corresponding key.

Vigenere Cipher is one kind of polyalphabetic cipher where the key stream is generated by repetition of the initial secret key of length 𝑚.

Algorithm