These vary the number of spaces shifted in a recurring pattern.

So if a 1,2,1,2 Caesar shift is used, a b c becomes B D D … so D represents both b and c.

The 15th century polymath Leon Alberti had this brilliant idea of combining ciphers – making life much safer for code makers, but much harder for code breakers.

JCC Advanced Caesar Code Challenges

Can you crack the following code using this rhyme?

You see I love a lot of books,                          

As maybe you do too?                  

So from an all-time favourite,

I’ve picked a quote for you.

The start of it’s in code below,

My gmail gives a clue,

And if you haven’t read it yet,

I recommend you do.

M   QGER   KQEIMRG   LSY   WSOI   YPJSTXYPEXG   QEUXIT

Or, even harder, can you decipher the name of one of Julius Caesar’s most important contemporaries using the year of his (not Caesar’s) birth?

NAXDUY UURMIAT CODEXP

If you managed either, you are really smart. If you managed both, you’re amazing!