Suppose you have this plaintext: "BYE" and this plaintext is now transformed into a ciphertext: "AXD" knowing that the encryption algorithm used is transposition "shifting each character by its previous character". How can you determine the used key size in (bits)? and How can you determine the time required to decrypt that message using a "Brute Force Search"? Please explain them and for sure give me the answer for both of them.