once”.
‘A cipher is when you scramble the actual sentence, using the same number of letters. If you wanted to send “The Fleet is to put to sea” in cipher you would scramble up the letters of all the words and transmit the jumble. Of course, the receiver of the signal has to know how to unscramble it and read the original meaning.
‘With Enigma, we are concerned only with ciphers,’ he said. ‘In fact ciphers are the key to wars. Ciphers, if you can break them, in effect let you listen to a microphone placed in the enemy’s headquarters.
‘The old way of sending a message in cipher meant referring to a book, rather like a dictionary, to change each letter of the signal into something else — into what would be a meaningless jumble to the enemy. There are problems. For example, take the word “add”. In a particular cipher, A may become H, and D is W, so “add”, in cipher is “HWW”. Any cryptologist worth his salt would spot that, so having worked out that H is in fact A, and W is D, he looks for more clues like that and finally breaks the cipher and reads the signal.’
‘How the hell can anyone send signals that the enemy can’t break?’ Jemmy demanded.
‘Telepathy,’ Ned muttered. ‘That’s the answer. Or tom-toms at short range.’
‘I agree about telepathy,’ Jenson answered, his face serious. ‘I think it has great possibilities, but I can’t interest my colleagues.’
‘Where does Enigma come into all this?’ Jemmy asked. ‘Just a superior crystal ball?’
Ned decided that Jenson was completely humourless: no joke or wry remark ever intruded into his life (or, rather, was ever recognized).
In the flat tone of a true academic, Jenson began: ‘Enciphering a message which has to be transmitted by a means the enemy can overhear (by wireless, for instance) means that the words of the message have to be scrambled in a completely random way, and the chances of it being broken are lessened if each time the same letter is repeated in the message it becomes a different one in the scramble.
‘For example, say A is Z the first time it is used, K the second, R the third and so on.
‘But war today is fast moving, particularly where armies are concerned. There isn’t time to decipher long signals by turning the pages of a cipher book, particularly while you are being bombed or shelled, and it will probably be raining, too.’
‘Enigma?’ Jemmy prompted hopefully.
‘So the ideal way to encipher a message before transmitting it by wireless is a mechanical means: in other words something like a special typewriter. You type the actual letters of the message in plain language on to the keyboard, but what you read as you hit each key is another letter, so instead of the original plain message you now have an apparently meaningless scramble. And a special refinement would be that, as you type each, it not only produces the enciphered letter but then changes, so that the next time that particular letter comes up, it is enciphered differently.’
‘And that’s what Enigma does?’ Ned asked.
‘That was my bird,’ Jemmy complained.
‘Basically that’s what the Germans did when they produced Enigma,’ Jenson said pedantically. ‘They added a battery, a nice mahogany box, a manual for each cipher — and here you have it.’ He patted the box. ‘Just like a portable typewriter — which is what is really is.’
‘But what happens when someone picks up the signal after Enigma has scrambled it?’ the Croupier asked.
‘Ah, that’s quite simple. That person would need to be listening on an assigned frequency, have a manual for the particular cipher, and an Enigma machine — which have been issued by the hundred.
‘Let’s suppose Hans Schmidt is the wireless operator of the 15th Panzer Division in the Western Desert and the Ober Kommando der Wehrmacht in Berlin has a signal for the general commanding.
‘The OKW signals people get the message at headquarters in plain language
‘A cipher is when you scramble the actual sentence, using the same number of letters. If you wanted to send “The Fleet is to put to sea” in cipher you would scramble up the letters of all the words and transmit the jumble. Of course, the receiver of the signal has to know how to unscramble it and read the original meaning.
‘With Enigma, we are concerned only with ciphers,’ he said. ‘In fact ciphers are the key to wars. Ciphers, if you can break them, in effect let you listen to a microphone placed in the enemy’s headquarters.
‘The old way of sending a message in cipher meant referring to a book, rather like a dictionary, to change each letter of the signal into something else — into what would be a meaningless jumble to the enemy. There are problems. For example, take the word “add”. In a particular cipher, A may become H, and D is W, so “add”, in cipher is “HWW”. Any cryptologist worth his salt would spot that, so having worked out that H is in fact A, and W is D, he looks for more clues like that and finally breaks the cipher and reads the signal.’
‘How the hell can anyone send signals that the enemy can’t break?’ Jemmy demanded.
‘Telepathy,’ Ned muttered. ‘That’s the answer. Or tom-toms at short range.’
‘I agree about telepathy,’ Jenson answered, his face serious. ‘I think it has great possibilities, but I can’t interest my colleagues.’
‘Where does Enigma come into all this?’ Jemmy asked. ‘Just a superior crystal ball?’
Ned decided that Jenson was completely humourless: no joke or wry remark ever intruded into his life (or, rather, was ever recognized).
In the flat tone of a true academic, Jenson began: ‘Enciphering a message which has to be transmitted by a means the enemy can overhear (by wireless, for instance) means that the words of the message have to be scrambled in a completely random way, and the chances of it being broken are lessened if each time the same letter is repeated in the message it becomes a different one in the scramble.
‘For example, say A is Z the first time it is used, K the second, R the third and so on.
‘But war today is fast moving, particularly where armies are concerned. There isn’t time to decipher long signals by turning the pages of a cipher book, particularly while you are being bombed or shelled, and it will probably be raining, too.’
‘Enigma?’ Jemmy prompted hopefully.
‘So the ideal way to encipher a message before transmitting it by wireless is a mechanical means: in other words something like a special typewriter. You type the actual letters of the message in plain language on to the keyboard, but what you read as you hit each key is another letter, so instead of the original plain message you now have an apparently meaningless scramble. And a special refinement would be that, as you type each, it not only produces the enciphered letter but then changes, so that the next time that particular letter comes up, it is enciphered differently.’
‘And that’s what Enigma does?’ Ned asked.
‘That was my bird,’ Jemmy complained.
‘Basically that’s what the Germans did when they produced Enigma,’ Jenson said pedantically. ‘They added a battery, a nice mahogany box, a manual for each cipher — and here you have it.’ He patted the box. ‘Just like a portable typewriter — which is what is really is.’
‘But what happens when someone picks up the signal after Enigma has scrambled it?’ the Croupier asked.
‘Ah, that’s quite simple. That person would need to be listening on an assigned frequency, have a manual for the particular cipher, and an Enigma machine — which have been issued by the hundred.
‘Let’s suppose Hans Schmidt is the wireless operator of the 15th Panzer Division in the Western Desert and the Ober Kommando der Wehrmacht in Berlin has a signal for the general commanding.
‘The OKW signals people get the message at headquarters in plain language
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