The buildCipher function could create more complicated alphabets. As long as both the receiver and the sender generate the alphabet in the same way, the message needs to only include the keyword for encoding and decoding to work. Try building these variations:

• Put the keyword at the end of the alphabet, rather than the front.

• Reverse the alphabet before concatenating it to the keyword.

• Separate the vowels and the consonants in the rest of the alphabet so that the cipher alphabet is keyword, then the rest of the vowels, then the rest of the consonants.