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US Navy Mathematicians vs JN-25

US Navy Mathematicians vs JN-25. Chris Christensen Northern Kentucky University. Ciphers. The Polish Codebreakers. Bletchley Park. The Prelude to US Entry into WW II. The Search for “Cipher Brains”. Correspondence Course. Assignment Three Numerical Cipher Alphabets.

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US Navy Mathematicians vs JN-25

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  1. US Navy Mathematicians vs JN-25 Chris Christensen Northern Kentucky University

  2. Ciphers

  3. The Polish Codebreakers

  4. Bletchley Park

  5. The Prelude to US Entry into WW II

  6. The Search for “Cipher Brains”

  7. Correspondence Course

  8. Assignment ThreeNumerical Cipher Alphabets

  9. Assignment Three: Problem 2

  10. OP-20-GM Naval Communications Washington, DC

  11. US Navy Cryptologic MathematiciansOctober 1945

  12. Mathematicians Alfred Clifford MIT (Top, 1) Marshall Hall, Jr. Yale (Middle, 2) Andrew Gleason Harvard (Middle, 5)

  13. Mathematicians Howard Engstrom Yale (Top, 5) Lawrence Steinhardt MIT student (Top, 8)

  14. Mathematicians Howard Campaigne Minnesota (Top, 10) Reed B. Dawson Illinois (Top, 11) William A. Blankinship (Top, 12) William Wray Williams (Bottom, 6) J. J. Eachus Purdue (Middle, 6)

  15. NCML National Cash Register Dayton, OH

  16. Joseph Desch (1907 – 1987) 2011 Inductee

  17. JN-25

  18. Intercepted Message

  19. JN-25

  20. 5-Digit Code hatsu from 58743, 78225 shuushifu full stop 50418 maru ship name 76833 begin 45435 good 34131 commander-in-chief 41595 radio silence 66201

  21. Additives Encipher Decipher “Full stop” 50418 Additive 65358 False sum 15766 Transmitted15766 Additive 65358 “Full stop” 50418

  22. Message 67854 59199 76833 57699 10047 70863 06138 27924

  23. Table of Additives

  24. Encipher 67854 59199 76833 57699 10047 70863 06138 27924 13014 71230 48387 38057 89496 54980 91681 22764 70868 20329 14110 85646 99433 24743 97719 49688

  25. Indicator 30441

  26. Indicators

  27. Vertical Alignment of Messages

  28. Differencing (Codegroup 1 + Additive) (Codegroup 2 + Additive) Codegroup 1 – Codegroup 2

  29. Differencing 38094 43682 95412 15698

  30. Differencing

  31. Differencing

  32. Scanning 67854 59199 76833 57699 10047 70863 06138 27924

  33. Differencing and Scanning

  34. Dayton, OH 21 December 1942 … we also saw a machine for aiding one in the recovery of subtractor groups when messages have been set in depth. A rather similar machine was made by Letchworth for us in early 1940, and although not nearly so convenient as this model, has been used quite a bit I believe. Alan Turing

  35. CXDG-CNN-10-ADW “Fruit”

  36. Fruit Display Colors

  37. Scanning Combinations

  38. Depth

  39. Zeroize by B

  40. Differencing D – B = 15103 B = 89172

  41. Differencing

  42. Results

  43. 1942 and 1943 JN-25

  44. Copperheads I - V 1943 The cryptologic crisis of the Battle of the Atlantic eased, and Lt. Lawrence Steinhardt was assigned the responsibility of designing machines to attack Japanese additive cipher systems.

  45. Two Problems Align message groups vertically – in depth Align message groups and recovered additives

  46. Align Message Groups Vertically – in Depth Copperhead I

  47. Double Repeats 05661 06511 07465 07495 12143 14240 14963 18673 78009 57047 79519 06511 90318 72216 12143 94860 70240

  48. Double Repeats 05661 06511 07465 07495 12143 14240 14963 18673 40876 06511 90318 72216 12134 94860 70240 54911 32814

  49. Double Repeats

  50. Copperhead I Align messages in depth

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