practice cryptanalysis - temple university cryptanalysis 1. 2 example ciphertext amu qc, py dxrrci...
TRANSCRIPT
![Page 1: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/1.jpg)
Practice Cryptanalysis
1
![Page 2: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/2.jpg)
2
Example Ciphertext
AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL OCFMTLY. PY DXRRCI OWTWKXMQ CD TNX ICLRU, AQZ MCT INAT APXLWOAM IWRR UC DCL YCF, BFT INAT TCEXTNXL IX OAM UC DCL TNX DLXXUCP CD PAM. DWMARRY, INXTNXL YCF ALX OWTWKXMQ CD APXLWOA CL OWTWKXMQ CD TNX ICLRU, AQZ CD FQ NXLX TNX QAPX NWEN QTAMUALUQ CD QTLXMETN AMU QAOLWDWOX INWON IX AQZ CD YCF. IWTN A ECCU OCMQOWXMOX CFL CMRY QFLX LXIALU, IWTN NWQTCLY TNX DWMAR HFUEX CD CFL UXXUQ, RXT FQ EC DCLTN TC RXAU TNX RAMU IX RCJX, AQZWME NWQ BRXQQWME AMU NWQ NXRS, BFT ZMCIWME TNAT NXLX CM XALTN, ECU'Q ICLZ PFQT TLFRY BX CFL CIM.
![Page 3: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/3.jpg)
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Plan of Attack
● What should we do?● count
– single characters– digrams– trigrams?
● look for– double letters– individual words that jump out at us
![Page 4: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/4.jpg)
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Character Counts
● single character counts
![Page 5: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/5.jpg)
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Character Counts
● single character counts
● single character counts (sorted):
![Page 6: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/6.jpg)
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Character Counts● single character counts
● single character counts (sorted):
● English frequency distribution:
● Guesses?
![Page 7: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/7.jpg)
7
Character Counts
● ciphertext char counts
● english
● guesses now?
![Page 8: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/8.jpg)
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Character Counts
● ciphertext char counts
● english
● High frequency letters {C,X,A,T,L} probably from set {E,T,A,O,N}Low frequency letters {H,J,S,G,V} probably from set {J,K,X,Q,Z}
![Page 9: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/9.jpg)
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Ciphertext Again
AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL OCFMTLY. PY DXRRCI OWTWKXMQ CD TNX ICLRU, AQZ MCT INAT APXLWOAM IWRR UC DCL YCF, BFT INAT TCEXTNXL IX OAM UC DCL TNX DLXXUCP CD PAM. DWMARRY, INXTNXL YCF ALX OWTWKXMQ CD APXLWOA CL OWTWKXMQ CD TNX ICLRU, AQZ CD FQ NXLX TNX QAPX NWEN QTAMUALUQ CD QTLXMETN AMU QAOLWDWOX INWON IX AQZ CD YCF. IWTN A ECCU OCMQOWXMOX CFL CMRY QFLX LXIALU, IWTN NWQTCLY TNX DWMAR HFUEX CD CFL UXXUQ, RXT FQ EC DCLTN TC RXAU TNX RAMU IX RCJX, AQZWME NWQ BRXQQWME AMU NWQ NXRS, BFT ZMCIWME TNAT NXLX CM XALTN, ECU'Q ICLZ PFQT TLFRY BX CFL CIM.
![Page 10: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/10.jpg)
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Guesses
● So Q is probably S (maybe T)
● A is either O, A, or I
– O is unlikely– I is more likely, except that I doesn't begin
many words as it does in the ciphertext– A seems like a good guess.
![Page 11: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/11.jpg)
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First Part
![Page 12: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/12.jpg)
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What is 'Z'?
![Page 13: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/13.jpg)
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The Letter 'Z'
● We have
● It could be:– ash– ask– asp– ass
![Page 14: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/14.jpg)
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The Letter 'Z'
● We have ● It could be:
– ash– ask– asp– ass
Can't be “ass”Probably not “asp”.
What about “ask” or “ash”?
![Page 15: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/15.jpg)
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“ash” or “ask”?
● They're not exactly the same, but “K” looks like a much better match.
● single character counts (sorted):
● English frequency distribution:
![Page 16: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/16.jpg)
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Z is probably K
![Page 17: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/17.jpg)
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What about 'C'?
![Page 18: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/18.jpg)
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C must be O
![Page 19: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/19.jpg)
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What is 'U'?
![Page 20: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/20.jpg)
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The Letter U
● It's probably either a 'T' or a 'D' → “to” or “do”– could also be “do” and “go”
● ciphertext char counts
● English
● How many times should we expect to see “T”?
![Page 21: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/21.jpg)
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Try 'D'
![Page 22: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/22.jpg)
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Come on. This one is too easy.
![Page 23: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/23.jpg)
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What about 'T'?
![Page 24: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/24.jpg)
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The letter 'T'
● We have:
● What could it be?
![Page 25: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/25.jpg)
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The letter 'T'
● We have:
● What could it be?nodnonnornotnow
![Page 26: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/26.jpg)
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The letter 'T': context
● What could it be?– nod– non– nor– not– now
● ask nod?● ask non?● ask nor?● ask not?● ask now?
![Page 27: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/27.jpg)
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Try T = T
![Page 28: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/28.jpg)
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What is 'D'?
![Page 29: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/29.jpg)
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What about 'D'?
● Two letter word, begins with O.● Could be:
– of– oh– on– or– ox– oz
![Page 30: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/30.jpg)
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What about 'D'?
● Two letter word, begins with O.● Could be:
– of– oh– on– or– ox– oz
no.
![Page 31: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/31.jpg)
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What about 'D'?
● Two letter word, begins with O.● Could be:
– of– oh– on– or– ox– oz
● no. probably not
![Page 32: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/32.jpg)
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“of” or “or”?
● look at the frequencies again● ciphertext char counts
● English
![Page 33: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/33.jpg)
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Substitute 'F'
![Page 34: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/34.jpg)
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Now how about 'L'?
![Page 35: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/35.jpg)
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The letter 'L'
● FO_ could be:– foe– fog– for– fox
● Look at context again.
![Page 36: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/36.jpg)
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The letter 'L'
● FO_ could be:– foe– fog– for– fox
● Look at context again.– do foe?– do fog? – do fox?– do for?
![Page 37: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/37.jpg)
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The letter 'L'
● FO_ could be:– foe– fog– for– fox
● Look at context again.– do foe?– do fog? – do fox?– do for?
![Page 38: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/38.jpg)
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“fox” or “for”?
● look at the frequencies again● ciphertext char counts
● English
![Page 39: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/39.jpg)
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Substitute 'R'
![Page 40: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/40.jpg)
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Probably Know Answer. If not:
● Common digrams in the ciphertext
● Common digrams in EnglishEN, RE, ER, NT, TH
![Page 41: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/41.jpg)
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Probably Know Answer. If not:
● Common digrams in the ciphertext
● Common digrams in English
– EN, RE, ER, NT, TH
● Consider:digramsremaining free letterswe have 45 X's in the ciphertextIt has to be “THE”
![Page 42: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/42.jpg)
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Substitute 'R'
![Page 43: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/43.jpg)
43
“I” must be “W”
![Page 44: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/44.jpg)
44
So far
● So far, we have
● But we already know the answer.
![Page 45: Practice Cryptanalysis - Temple University Cryptanalysis 1. 2 Example Ciphertext AMU QC, PY DXRRCI APXLWOAMQ, AQZ MCT INAT YCFL OCFMTLY OAM UC DCL YCF; AQZ INAT YCF OAM UC DCL YCFL](https://reader031.vdocuments.site/reader031/viewer/2022030616/5ae17b4d7f8b9ab4688ebf71/html5/thumbnails/45.jpg)
45
Plaintext
Which is anything but plain.
“And so, my fellow Americans, ask not what your country can do for you; ask what you can do for your country. My fellow citizens of the world, ask not what America will do for you, but what together we can do for the freedom of man.
Finally, whether you are citizens of America or citizens of the world, ask of us here the same high standards of strength and sacrifice which we ask of you. With a good conscience our only sure reward, with history the final judge of our deeds, let us go forth to lead the land we love, asking His blessing and His help, but knowing that here on earth, God's work must truly be our own.”