Kryha Cryptanalysis - Parker Hitt's 1929 feat

• Cryptograms in-depth

Introduction

The cipher machine Kryha was evaluated and rejected early in 1930 by the U.S. Army. The evaluation was carried out by Col. Parker Hitt. Manuscripts of two documents (which date from 1929 and 1930) describing his solution have survived. Frode Weirund made these documents available (cf. Reference).

This page is dedicated to deciphering the 1929 message.

Cryptograms

Here are the begining of the cryptograms analyzed by Parker Hitt (first 26 letters only). These messages are in-depth. It was these initial elements that were used for decryption.

      1. R S C G D G P M Y A Z Z T Q E G T P K Y B L X J K O
      2. S M J D E G D O P A R Z S A A S C S K B C U S Z N Z
      3. H R L H R Z E Q Y V K B J R E P K C Y K V I E G U Z
      4. H W J G Y G X B U W B L Q F R Y R D E K K H L F E F
      5. T V H N M X F R K G R F H Q C F P T P B R Q K G N B
      6. E F H T B B F O Y W R O P D E K K D Y W I I J E Y B
      7. Q L B B A D N Z K Y K I H F Z F H I J T B C J F K O
      8. F T C H J Z D M C N J U P K A F H X J K Q C J M V N
      9. O L X M A Z Y O M B R E H R D P P D Y C F C Y H B G
     10. H W J G N X F N A U K F S A Y I K D Q W J L U O Q Z
     11. Q L D H B X L X S B U S H L S F B V P L F U Z G U O
     12. E F H M A W Y O H B U S H F U G E F L W V I T H T C
     13. H W J M A F E B I B P L J D R N N P Q Y H G C J U I
     14. C R S H E Z D O P A R Z S R R Y K X D B P U S Z D N
     15. H W P F R P I M P R S S E D R P P P K Y E I K H D V
     16. O L R H B P A Z U N N P J R D D E L U O N L D Q C I
     17. I U J M S F K Q Q N S G H D A U T W L A B Q J P T F
     18. F L X Y E I M X Y G H O N N K G Y B E I K G K X V D
     19. S Z J C T X Y M A O S A H V T T R P R N B G J K Q B

$ cat PARKER_1929/msg_01.cry
RSCGD GPMYA ZZTQE GTPKY BLXJK
OQDJO NGJAH NCQKE NXNCP ZSDBP
PKNCN WHQVA JISVD TRFJU TGJWF
SUKCX HNKNG RFELI GXIZR JHEWX
RUHAL AOMVA CRIWP UVYSV NYOZC
OGDPB VWOWL

The Key

Parker Hitt reconstituted the key. The wheel used did not match the standard wheel.

• The shifts for each sector: 3,2,3,1,2,3,2,4,2,6,1,2,1,3,2,1,5
• Internal Alphabet: YNCPZTDQEFSRGUAHVOJWLKXIBM
• External Alphabet: MCLQGBURIDPFNOATVSZYJXHEWK

Here is the comment given by Frode Weierud:

"The recovered stepping patterns are puzzling in that they do not correspond to any version of the Kryha machine that has been described in the cryptographic literature. They do, however, correspond exactly to a common version of the control wheel found in early models of the Kryha machine. These models produce displacements that are equal to a constant factor plus the number of teeth in the active segment of the control wheel; at the time of transcription it was not clear whether the constant factor is 3 or 4, but evidence from historical documents strongly suggests that it is 4. So Hitt’s ciphertexts were either produced from an earlier version of the machine or perhaps via an experimental, manual encipherment based on partial knowledge of the machine."

Deciphering

$ cat parker1929.sh
python3 kryha_tui.py -o \
    -i YNCPZTDQEFSRGUAHVOJWLKXIBM \
    -e MCLQGBURIDPFNOATVSZYJXHEWK \
    -s 3,2,3,1,2,3,2,4,2,6,1,2,1,3,2,1,5 \
    -d

$ echo RSCGDGPMYAZZTQEGTPKYBLXJKO | sh parker1929.sh
FORJTESTJPURPOSESJTHEJWELL

$ echo SMJDEGDOPARZSAASCSKBCUSZNZ | sh parker1929.sh
PLEASEJREPORTJEXACTJCONDIT

$ echo HRLHRZEQYVKBJREPKCYKVIEGUZ | sh parker1929.sh
TAKEJTHEJNECESSARYJSTEPSJT

$ echo HWJGYGXBUWBLQFRYRDEKKHLFEF | sh parker1929.sh
THEJDEPARTMENTJFEELSJTHATJ

$ echo TVHNMXFRKGRFHQCFPTPBRQKGNB | sh parker1929.sh
BYJDIRECTIONJOFJTHEJPRESID

$ echo EFHTBBFOYWROPDEKKDYWIIJEYB | sh parker1929.sh
INJORDERJTOJINSUREJTHEJORD

$ echo QLBBADNZKYKIHFZFHIJTBCJFKO | sh parker1929.sh
REQUESTJTHEMJTOJCANCELJALL

$ echo FTCHJZDMCNJUPKAFHXJKQCJMVN | sh parker1929.sh
DIRECTJTHEJVICEJCONSULJGEN

$ echo OLXMAZYOMBREHRDPPDYCFCYHBG | sh parker1929.sh
SECRETARYJOFJSTATEJWILLJBE

$ echo HWJGNXFNAUKFSAYIKDQWJLUOQZ | sh parker1929.sh
THEJPRESIDENTJDIRECTSJTHAT

$ echo QLDHBXLXSBUSHLSFBVPLFUZGUO | sh parker1929.sh
REFERRINGJTOJMYJPREVIOUSJL

$ echo EFHMAWYOHBUSHFUGEFLWVITHTC | sh parker1929.sh
INJREGARDJTOJTHEJMATTERJNO

$ echo HWJMAFEBIBPLJDRNNPQYHGCJUI | sh parker1929.sh
THEREJHASJBEENJNOJCHANGEJI

$ echo CRSHEZDOPARZSRRYKXDBPUSZDN | sh parker1929.sh
LATESTJREPORTSJFROMJLONDON

$ echo HWPFRPIMPRSSEDRPPPKYEIKHDV | sh parker1929.sh
THISJAFTERNOONJATJTHREEJOC

$ echo OLRHBPAZUNNPJRDDELUONLDQCI | sh parker1929.sh
SEVERALJREQUESTSJFROMJINDI

$ echo IUJMSFKQQNSGHDAUTWLABQJPTF | sh parker1929.sh
EVERYJDECENTJNEWSPAPERJINJ

$ echo FLXYEIMXYGHONNKGYBEIKGKXVD | sh parker1929.sh
DECISIONJISJURGENTLYJNECES

$ echo SZJCTXYMAOSAHVTTRPRNBGJKQB | sh parker1929.sh
PREPARATIONSJHAVEJBEENJMAD

The Plain text of the first cryptogram

We replace each letter J with a space.

$ sh parker1929.sh < PARKER_1929/msg_01.cry | sed -e 's/J/ /g'
FOR TEST PURPOSES THE WELL KNOWN SENTENCE QUOTE THE QUICK BROWN 
FOX IUMPS OVER TPE LAZY DOGS BACK UNQUOTE WILL BE USED BY ALL STATIONS

Reference

• Frode Weierud - The Kryha Cipher Machine - Transcript of 1929 manuscript written by Parker Hitt. link