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Chris Christensen Department of Mathematics and Statistics Northern Kentucky University
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norsenorsenorsenorseno ringlearningwitherrors EWEYPROIFMAUNAXUSIJSEG
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We need enough key to “cover” the plaintext.
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thelearningwitherrorsproblemaskstore departmentofmathematicsandstatistics WLTLVTDRVGUBUTALVDOKARJOOOWFALSKMWTW
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Key should be random.
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Pearl Harbor
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1 June 1939
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00331
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(Clear Codegroup 1 + Additive) (Clear Codegroup 2 + Additive) Clear Codegroup 1 – Clear Codegroup 2
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30 November 1943 “Tentative Method for the Alignment of JN-25 Traffic Without Use of Code or Keys.” Lawrance Shinn Ray C. Hackman
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0 0 1 2 6 2 10874 96807 20360 07131 11248 44860 4 5 2 2 19374 97405 03289 35158
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My initial reaction to it was to wonder why anyone would go down that road. Collapsing five-figure groups into mod 10 sums of their digits loses an awful lot of information.
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Differences of Scanning Groups Distribution of Differences
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DifferenceShinn Weights 0438 1 or 9300 2 or 8249 3 or 7418 4 or 6365 5230
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781321 069364 7418 3418
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Mean random334.3 Mean correct349.5 Standard deviation random72.86 Standard deviation correct73.45
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0 0 1 2 6 2 10874 96807 20360 07131 11248 44860 4 5 2 2 19374 97405 03289 35158 7 7 4 0 418 418 365 438 0.8 standard deviations above the mean of correct alignment
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0 0 1 2 6 2 10874 96807 20360 07131 11248 44860 4 5 2 2 19374 97405 03289 35158 6 5 9 0 365 230 300 4 standards deviations below the mean of correct alignment
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Key cannot be reused.
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One-Time Pad OTP
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