More Examples: here is another short example, see if your algorithm matches,

For vigenere, when the letter is not in the alphabet for the key, exit the program and error out. When a letter in

the plaintext is not in the alphabet, pass it through but do not count it as a character against the key $($that is keep

the current key index, skipping over non alphabet characters in plaintext, and use it for the next valid alphabet

character$).$ Do this both for encryption and decryption $[$since passthrough can put non$-$alphabet characters in

cyphertext$].$

key $=$ box $,$ alphabet $=[a-z]\{$lowercase only in other words

For any code IF REQUIRED please use Java!!