Auto Key Cipher

Autokey (Autoclave) Cipher is a Symmetric polyalphabetic (Polyceaser) substitution cipher. This algorithm is about changing plaintext letters based on secret key letters. Each letter of the message is shifted along some alphabet positions. The number of positions is equal to the place in the alphabet of the current key letter.

Note: Cipher text is also called as encrypted text(don't confuse). And we're assuming index starting from 0 not 1.

Example Test Cases

Case-1:

Input:

Enter the Single Key ...