Read Online THE LAST GOOD WAR: A Novel by Paul Wonnacott - Free Book Online Page B
Authors: Paul Wonnacott
Tags: Fiction / War & Military
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the way up to the time of the invasion of France in May 1940, when the Germans would have another particularly nasty surprise.
When they sat down for the regular Wednesday meeting, Henryk asked Anna, as the raporteur, to sum up the current situation as she saw it; this would give them a starting point.
Unconsciously, Anna sat a bit straighter in her chair, giving a formality to her report. “There are obviously two parts of the puzzle: the wheels from the original Enigma—the scrambler, in other words—plus the steckerboard. Our basic problem is: how can we solve the scrambler settings without first knowing the steckerboard settings, and vice versa? In other words, we have to solve both sets of settings—the wheels and the steckerboard— simultaneously .”
Anna noticed that Marian was stroking his beard. She continued.
“What do we know that might be helpful?
“First, some of the messages start with 'From,' or VON in German. It's not clear how much help that is. After it goes through the steckerboard, VON may be transmogrified into any three other letters. In spite of it all, there might be something here,” she said, trying to be upbeat. “We've also collected a list of other similar cribs.”
Marian was now stroking his beard even more slowly, more thoughtfully. Anna hoped he was still listening. She took up her story.
“Second, the pattern of messages has remained the same: a preamble followed by two sets of three letters, followed by a string, followed by groups of five letters. Thus, it is reasonable to assume that the two sets of three letters—the inscrutable six—still give the wheel settings. But how can we use that information? Again, it will go through the steckerboard, which will change all the letters from the scrambler. Again, we're driven back to our fundamental problem: it's hard to see how we can crack any corner of the problem without figuring out everything—wheels and steckerboard—at once. We will have to...”
Her voice trailed off because it looked as if Marian was ready to say something.
“I'm not so sure,” he began. “If we do what we did before, it's true that we would have to decode a message to figure out the inscrutable six. That brings us to our little problem of a billion billion possible settings.... But suppose we attack the inscrutable six directly, without a decoded message. Would that be possible?”
Henryk was about to say “How?” but caught himself; Marian was already continuing, slowly and thoughtfully.
“The way to start, it seems to me, would be to look for some clue in the six letters themselves. What would that be?”
He swallowed a sip of water and continued:
“What are the inscrutable six? Instructions on how the recipient should set the wheels to decode the incoming message. The instructions are repeated, giving two sets of three letters. For example:
PQR PQR
“But of course, this information is encrypted; any six letters may show up. Suppose we find an intercept that happens to give the same letter for the first and fourth position, for example:
ABC AFG
“Then we would know that we're at an interesting place in the wheels. If we first push a P, it comes out A after encryption. Three letters later, when we push P again, it once more comes out A. We might use that to pry open the problem.”
He paused for about a minute; everybody at the table was deep in thought.
“But I'm not sure that will help. There's still the steckerboard problem....”
“But is there?” responded Jerzy, his words tumbling out. “Isn't the steckerboard beside the point? Suppose, for example, that the A is steckered to K. Then, looking at the first and fourth positions of your example, the scrambler part of the machine would be kicking out
Kxx Kxx.
“In other words, the steckerboard is irrelevant for your basic conclusion. The initial setting of the wheels gives the same letter in positions 1 and 4—although we don't have any idea of what that letter might
When they sat down for the regular Wednesday meeting, Henryk asked Anna, as the raporteur, to sum up the current situation as she saw it; this would give them a starting point.
Unconsciously, Anna sat a bit straighter in her chair, giving a formality to her report. “There are obviously two parts of the puzzle: the wheels from the original Enigma—the scrambler, in other words—plus the steckerboard. Our basic problem is: how can we solve the scrambler settings without first knowing the steckerboard settings, and vice versa? In other words, we have to solve both sets of settings—the wheels and the steckerboard— simultaneously .”
Anna noticed that Marian was stroking his beard. She continued.
“What do we know that might be helpful?
“First, some of the messages start with 'From,' or VON in German. It's not clear how much help that is. After it goes through the steckerboard, VON may be transmogrified into any three other letters. In spite of it all, there might be something here,” she said, trying to be upbeat. “We've also collected a list of other similar cribs.”
Marian was now stroking his beard even more slowly, more thoughtfully. Anna hoped he was still listening. She took up her story.
“Second, the pattern of messages has remained the same: a preamble followed by two sets of three letters, followed by a string, followed by groups of five letters. Thus, it is reasonable to assume that the two sets of three letters—the inscrutable six—still give the wheel settings. But how can we use that information? Again, it will go through the steckerboard, which will change all the letters from the scrambler. Again, we're driven back to our fundamental problem: it's hard to see how we can crack any corner of the problem without figuring out everything—wheels and steckerboard—at once. We will have to...”
Her voice trailed off because it looked as if Marian was ready to say something.
“I'm not so sure,” he began. “If we do what we did before, it's true that we would have to decode a message to figure out the inscrutable six. That brings us to our little problem of a billion billion possible settings.... But suppose we attack the inscrutable six directly, without a decoded message. Would that be possible?”
Henryk was about to say “How?” but caught himself; Marian was already continuing, slowly and thoughtfully.
“The way to start, it seems to me, would be to look for some clue in the six letters themselves. What would that be?”
He swallowed a sip of water and continued:
“What are the inscrutable six? Instructions on how the recipient should set the wheels to decode the incoming message. The instructions are repeated, giving two sets of three letters. For example:
PQR PQR
“But of course, this information is encrypted; any six letters may show up. Suppose we find an intercept that happens to give the same letter for the first and fourth position, for example:
ABC AFG
“Then we would know that we're at an interesting place in the wheels. If we first push a P, it comes out A after encryption. Three letters later, when we push P again, it once more comes out A. We might use that to pry open the problem.”
He paused for about a minute; everybody at the table was deep in thought.
“But I'm not sure that will help. There's still the steckerboard problem....”
“But is there?” responded Jerzy, his words tumbling out. “Isn't the steckerboard beside the point? Suppose, for example, that the A is steckered to K. Then, looking at the first and fourth positions of your example, the scrambler part of the machine would be kicking out
Kxx Kxx.
“In other words, the steckerboard is irrelevant for your basic conclusion. The initial setting of the wheels gives the same letter in positions 1 and 4—although we don't have any idea of what that letter might
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