a$.$ Using Vigenere cipher, encrypt the word "questionsandanswers" using the key matrix.

b$.$ Encrypt the plaintext $$sendmoremoney$$ with the key stream

$9017231521141111289$

c$.$ Using the ciphertext produced in Part $($b$),$ find a key so that the cipher text decrypts to the plaintext $$cashnotneeded$.$

d$.$ Can a brute$-$force attacker decrypt the ciphertext from Part $($b$)$ so that it knows the original message in a deterministic manner?