Read Online Alphabetical by Michael Rosen - Free Book Online Page B

rhyming with ‘fly’. It means ‘Watch out, Caesar!’).
    Caesar (probably you) sits with his followers in the room, and Cassius the codebreaker says that whatever cipher (‘code’) Caesar uses he will be able to crack it. He needs to do this, he says, because Caesar is getting too big for his boots and he’s keeping an eye on him. Caesar says that Cassius thinks he’s clever but he’s not that clever. Cassius leaves the room, ready to take on the challenge. Someone can be chosen to stand guard on him to show that Cassius is not cheating by listening to what’s going on from outside the door.
    Caesar tells his followers that they are going to choose anobject in the room, and they’re going to write it in a ‘code’. He suggests to his followers that they use the N + 3 formula which is his favourite and no one has ever cracked it yet. Caesar and his followers choose an object, let’s say it’s ‘table’. Make sure that it’s a suggestion from one of the followers and not from Caesar. Vote on it so that it’s obviously not been chosen by Caesar. Caesar shows his followers how to make the two strips of the alphabets and apply the formula by sliding the strips. This will deliver ‘table’ as ‘wdeoh’. Hide the strips.
    Call Cassius back into the room. Cassius sits down and watches Caesar’s hand. When Caesar hands over the ciphered message ‘wdeoh’, he does so with three fingers on the paper but in a way that the others won’t see. Cassius reads that as ‘N + 3’ and cracks the code, putting on a great show of staring at the letters and doing magic signs and various kinds of hocus-pocus. Cassius then warns Caesar and his followers that he knows everything he’s up to and he had better watch out: ‘Cave, Caesar!’
    Someone in the room may say that Caesar and Cassius obviously worked this out beforehand. So suggest that Cassius goes out again. Choose another object. Change the formula to N + any other number. Call Cassius back, revealing this new number with the same method, leaving your fingers on the page when you hand over the ciphered message.
    Now, we can step up the complexity of this, if you have either the mind or the machine to do it. What you can do is change the formula each time you write a letter. So, you could decide to start with N + 1 for the first letter, then N + 2 for the second and so on all through the message you want to send. Or you could make it more complicated by using any sequence of numbers to decide how you make the cipher. You could use your phone number or the repeated use of your flat or house number.
    Another way of doing this without using numbers is to makean alphabet square. Your alphabet square is made up of the twenty-six letters across the top as your ‘real’ alphabet. Exactly underneath, you write out the alphabet twenty-six times. However, each time you write an alphabet one below the other, you slide it along by one letter. So, now, stretching down below each letter of the ‘real’ alphabet, you have twenty-six new ways of writing each of the letters from your real alphabet along the top. When you write a word using this square, you could write the first letter of your word using the first line, the second letter using the second line, the third letter the third line and so on. So the word ‘table’ would be made up of ‘u’ from the first line, ‘c’ from the second line, ‘e’ from the third line, ‘p’ from the fourth line, ‘j’ from the fifth line, making ‘ucepj’ as ‘table’, using the formula N + 1, N + 2, N + 3, N + 4, N + 5.
    This square is known as a ‘Vigenère Square’, named after a French ‘diplomat’ Blaise de Vigenère (1523–96). In 1586, he wrote Traicté des Chiffres, ou Secrètes Manières d’Escrire ( Treatise on Ciphers or