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Rubiks Code Challenge; Can we break the cube?
Topic Started: Apr 20 2006, 06:33 PM (824 Views)
Donald
NSA worthy
[ *  *  *  *  *  * ]
We have intercepted several messages from a spy who has been using the Rubiks code. The spy was testing his new encryption system and did some foolish things which may give us an advantage:

---
MESSAGE 1: (keyword 1)
This first message is 40 characters long, and has a cycle of 16, we are convinced it is a single letter repeated:

Code:
 
IEFCD LGHAM TQWRS BIEFC DLGHA MTQWR SBIEF CDLGH


---
MESSAGE 2: (keyword 1)
This message was created using the same keyword as the previous. We know that the content is a random KJV Bible text, but no idea which.

Code:
 
ULOWL BIVGR DLYHT FQVMN SVMIS QGQOE GACLU UFFIX TBIIY DRGBC OKWMA OQOXF CTNRC PXIYH XBCIY XQXGD LHRFI UMTYD MVFMQ LUHVI PSKGR PMLVI ETTYA EWYFW OWVEQ YEFMU WNWFB BQAIN BGKXE WGGOI BTPXO UGORX PVSDA MCBRV VFNFP EFBLP EWTLE ACMRA CCTRW CKKNE QDPLS GVESD BYDVY BKDPI AVVIB ENXXI HKMRO VATVD GCICB LGISP DLDAO ADXIB VBXQL FAOCG HKOFP EGGVF HUOPK CVRPL TBQQ


---
MESSAGE 3: (keyword 2)
At this point the spy changed to a different keyword. BUT, in this case, we intercepted the plain text message through another route, so we know the plain text, but not the keyword.

Code:
 
plain: THESE CRETT HINGS BELON GUNTO THELO RDOUR GOD
crypt: WNKXF KOLLY QVKBA CYYPM QDDAA IIFFI OYAQP BDN


---
MESSAGE 4: (keyword 2)
This is another random KJV Bible text, encrypted using the SAME keyword as message 3.

Code:
 
VWOLD BAFPL OOPOK XKVMY HGVXI CPSLV EOSYW XLHFY CAPKE KAQLY FNTYN KVARD PKOER BAKOK TOCGI QIBQH AMFYN UGBXD CYEVO PVOLD VFUTE TPORC FDCNW XGQTY SAQNW HGLTG RQURL PATRT SRKCX DUHBM YFBHP AUIDI AOKKD UCTHD LLCBB DWLCF IPYCC QHMYF AHIWP SBTPP PKPTK XRLGP WWPEK KFYFN FKVSS SOHRO WWSIG CVBQL EDDLC SHNSG MIPOR FSBLH DQOQD RQWRW CCXNB KHRFB DYOCP CQSYS LIAKE TWWPY YNBLW XAYR


---
MESSAGE 5: (keyword 3)
Unfortunanly, the only thing we know about this one is that its a different keyword and another random KJV text.

Code:
 
RGQSU ASGNH DDNPU TCPPR DSILF FPAXV YNUBU GHBRR GXMVK HYEWA HQYHN LKMFS DBWMK MCRNC TSPYV QTIEY QYFHF KBKPN WHXII RCXXW UTNKT VCFMD LYTGF IPKFO SDCFG AEGKT AYDMR BIHNG BQGPU SCNXN DYOEN BAPFN URKOE DBPVY RPWMQ RDHBX QXGPW UUNFR ASIWY OVKEY XSRIH GVVYP WITUE XHUMX MHGUS HLUHD SBDKN SMNAV QAVNE PFSIX BVKSB DQKHF KHHYV AEARW SLOWP SHCWB RMBLK RGBSQ XHBHD QPXND YPODR PMOVO PHVNS RUGCM NOQNS YOLNX HXCUH YPENT WUEEG QPKRV BVIPC OGACL PVXHE KLYXA RWSMT WHEDY WORCG QQMAV CQMFE SKMVL RKCNC UTBYG UDUIE EPLIH MMIMU SSKMM EHBNS AVQEF CWIGN XQPII LNHQU XNGLW YKETQ OEESM KFLLC CGQLF BRTFW URERG RXAUK NSXIG SHECB FGEA

=====================================================================

That gives us a good mix, and since I don't know any more about the contents then you guys, I can participate as well! :)

Good luck!
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Donald
NSA worthy
[ *  *  *  *  *  * ]
first observation:
boy there are a lot of doubles in the crypt for message 3!!!

LL YY DD AA II FF

That might help us when rebuilding the alphabet since it helps to link letters together.
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Donald
NSA worthy
[ *  *  *  *  *  * ]
I got the keyword for message 1!

Method was pretty simple:

To figure out how a letter moves around the cube when you encrypt one letter repeating over and over, I simply put in a null keyword alphabet (abc..wxy) and then encrypted a single letter repeated 16 times. THEN I backed up and showed the cube in its initial position and wrote down where the letters from the crypt text were on the cube.

So: our initial cube looks like:
Code:
 

.   |---|
.   | R |
.   |U S|
.   | T |
|---|---|---|---|
| N | A | E | I |
|Q O|D B|H F|M K|
| P | C | G | L |
|---|---|---|---|
.   | V |
.   |Y W|
.   | X |
.   |---|


And encrypting "a" 16 times results in: DVWQNBXYOCGKUHLP
So mapping that back onto our initial cube above we find our PATTERN on the cube is:
Code:
 

.   |---|
.   | . |
.   |13.|
.   | . |
|---|---|---|---|
| 5 | . | . | . |
|4 9|1 6|14.|.12|
|16 |10 |11 |15 |
|---|---|---|---|
.   | 2 |
.   |8 3|
.   | 7 |
.   |---|


Meaning that D was in the place marked 1, V was in the place marked 2, W was in the place marked 3, etc.

Now, since encryping a single repeating letter with ANY mixed alphabet will always move that letter through exactly the same patterns, we should be able to use the above "matrix" with the crypt text from message 1 to recreate much of the cube. The first letter of the crypt text goes into position 1, the second into position 2, etc.

Then its a matter of rotating the cube into a position that makes sense and filling in the rest of the alphabet.

I'll post more details if anyone wants them.

The known plaintext attack on message 3 really SHOULD be easy, but I haven't figured out an approach yet. Anyone else got any ideas?
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