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Cipher w ctak
Topic Started: May 17 2015, 02:14 PM (192 Views)
JOE.TEKK1
Elite member
[ *  *  *  *  * ]
A Message for Zetaboards Crypto.

The context is the communications system for an Executive Protection Detail for a corporation.

Cipher Text Autokey/Cipher Feedback is used.

UCJJC IMRLI FBGDB HFUD BIOBH PPOOI KOHJC
JPEBB BDFGE VEDRZ MEVZF
RQFHE JHXBJ SBGCI HNQWD XGACC AGTK JVBW



-----





















Plain message: YOU MUST GO TO GREENWICH (CONNECTICUT) AND WESTPORT TO

CHECK HOUSES CORAL AND JADE X HOUSE QUARTZ IS BEING RENOVATED X END .



We are using an alphabet where A=11, Z=36. The key is 12 characters, expanded on the

6 character key of “ QUICHE ” ; Q=VD, U=OW, I=HP, C=SA , H=WE, E=GO , then take

the 2nd and 4th digraphs again ( OW and SA ) as key letters, then use the W. Then key

of “HLQUAESWUYZQQUSWU . “ .





What would the message be if we used the 6-letter word of " PAELLA" as Key?



--end--
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JOE.TEKK1
Elite member
[ *  *  *  *  * ]
Zetaboards Message ; Key Expansion Cipher using key of “PAELLA” .



18 May 2015 : Note: This is the same message as previous example; except with different key .





Cipher: M X A A B H K F F S E E I D U B A A Z V A E F S G O G D B F …

Key : N V F N G O Q Y Q Y F N Q Y F N D H M D Z Q R V R V M D M D …

Plain: Y O U M U S T G O T O G R E E N W I C H A N D W E S T P O R …



Previous ( Keyword of “QUICHE” )



Cipher: U C J J C I M R L I F B G D B G H F U D B I O B H P P O O I ...

Key : V D O W H P S A W E G O O W S A W H L Q U A E S W U Y Z Q Q ...

Plain: Y O U M U S T G O T O G R E E N W I C H A N D W E S T P O R …



Key Expansion:



A=FN, B=PX, C=SA, D=LT, E=GO, F=XF, G=AI, H=WE <br>



I=HP, J=MU, K=BJ, L=QY, M=TB, N=IQ, O=CK, P=NV <br>



Q=VD, R=YG, S=DL, T=JR, U=OW, V=RZ, W=EM, X=ZH, Y=KS, Z=UC .



I hope I have not messed up too bad on the first message. The second PAELLA message should be ok.



Have a good week !





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