Crypto Challenge #3

[Hooman]

Well, since Challenge #2 is significantly harder than the first I thought I'd post an easier one in case someone wanted to give this a try but was having difficulty with #2. I did some basic analysis to make sure you can at least get a good easy start. This one should be about the same difficulty as the first, but is much shorter. (Shorter means less information you can use to crack it, but it also makes it easier to analyse/write out by hand, which I assume most people would be doing.) If you're into programming, feel free to write code to help you solve it. Things like finding the most frequently used letter can be tedious by hand.

Code: [Select]

JHM BMYSWT IDY EDQSUSDP JV HMP, D YJDTBDPB GDX EVP D BPSUU HVUM GPMDJMB AO VTM VE JHM PVAV-QVUMY CYMB ST QSTSTW VXMPDJSVTY.  TVJGHMY DCJVQDJSGDUUO MTWPDFMB ST JHM JVX GDX AO JHM BPSUUSTW QDGHSTM XPVFSBMB STEVPQDJSVT DAVCJ JHM BMXJH VE JHM HVUM, JOXM VE BPSUUSTW, DTB VJHMP BDJD.  D WUDTGM DJ SJ JVUB HMP JHDJ JHSY IDY D FMPO BMMX YHDEJ, YMFMPDU NSUVQMJMPY, DTB TMDPUO YJPDSWHJ BVIT, TVJ DJ DUU JHM NSTB VE HVUM VTM IVCUB CYM EVP QSTSTW.

YHM YDJ BVIT TMLJ JV JHM GDX JV IDSJ EVP IC'Y PMJCPT.  YHM PDT HMP WUVFMB HDTB VFMP JHM GDX DTB JHM PSTW VE YUVJY DPVCTB JHM JVX BMYSWTMB JV FMTJ DTO CTBMPWPVCTB WDYYMY JHDJ QSWHJ AM WMTMPDJMB.  DY YHM BSB, YHM YDI BCYJ BDTGSTW DUVTW JHM YCPEDGM VE JHM TMDPAO PVGN EDGM.  TVJ AMUSMFSTW HMP MOMY, YHM WPDAAMB D ESYJECU VE BCYJ EPVQ JHM AVJJVQ VE JHM GUMEJ DTB HMUB SJ TMDP JHM YUVJY.  YUVIUO, UDOMP AO UDOMP, SJ IDY AUVIT DIDO AO JHM VCJEUVI VE WDY.  YHM BSBT'J HDFM D IDO JV JMYJ SJ, ACJ YHM IDY GMPJDST JHDJ JMYJSTW IVCUB PMFMDU VLOWMT DTB IDJMP FDXVP, YVQMHVI AMSTW WMTMPDJMB BMMX ST JHM PVGNY, XVYYSAUO AO ADGJMPSDU DGJSVT.

JHSY IDY JHM MFSBMTGM YHM'B AMMT UVVNSTW EVP, JHSY IDY HDPB XPVVE VE MBMT'Y DGJSVTY, MFSBMTGM YHM GVCUB XPMYMTJ ISJHVCJ GPMDJSTW YCYXSGSVT.

"MQQD, OVC'PM DUU PSWHJ?" YHM WUDTGMB CX JV YMM JHM YCPFMOVP PVUU DPVCTB JHM MTB VE JHM HCWM PVGN.

"S'Q ESTM, IC.  WMJ JHM GDQMPDY DTB JHM YDQXUSTW WMDP.  IM HDFM IVPN JV BV AMEVPM IM HMDB HVQM."

[zanco]

Hmmm, it looks like no one besides me has the answer and/or is interrested in solving this one. I will wait a couple of hours before posting my answer.  :whistle:  

[zanco]

I've waited long enough.

Here comes the text in English.  B)

The design was familiar to her, a standard cap for a drill hole created by one of the robo-moles used in mining operations. Notches automatically engraved in the top cap by the drilling machine provided information about the depth of the hole, type of drilling, and other data. A glance at it told her that this was a very deep shaft, several kilometers, and nearly straight down, not at all the kind of hole one would use for mining.

She sat down next to the cap to wait for Wu's return. She ran her gloved hand over the cap and the ring of slots around the top designed to vent any underground gasses that might be generated. As she did, she saw dust dancing along the surface of the nearby rock face. Not believing her eyes, she grabbed a fistful of dust from the bottom of the cleft and held it near the slots. Slowly, layer by layer, it was blown away by the outflow of gas. She didn't have a way to test it, but she was certain that testing would reveal oxygen and water vapor, somehow being generated deep in the rocks, possibly by bacterial action.

This was the evidence she'd been looking for, this was hard proof of Eden's actions, evidence she could present without creating suspicion.

"Emma, you're all right?" she glanced up to see the surveyor roll around the end of the huge rock.
"I'm fine, Wu. Get the cameras and the sampling gear. We have work to do before we head home."



I pretty much used the same method I used in the previous challenge (shortest word first and apostrophe). In this CODE for example, the shortest words ( 1 character) was: 'S' and 'D'. Since 'S' was with written with 'Q' as in " S'Q ,"  I deduced that it could only be " I'm " and 'D' could only be 'a'. So at first glance, I had gotten 3 words.    I didn't have enough information for the other two "one-character words" 'Y' and 'J' ,though I knew those could only be "s" or "d" given that they came right after the apostrophe.

Words with two letters now: "JV" "DJ" "AO" "ST" ect... I know 'D'='a' so "AO" seemingly is equal to "at" or "an" ; I also know that 'S'= 'I' so "ST" = "IF" or "IS" , but "IF" is more likely to work.
However, the most interesting thing is with "JV" and "DJ". One letter is repeated twice : 'J' ... let's think a little... this looks like "TO" and "AT". BINGO! I have 4 more words.



I gave this information to get more people into taking up those crypto challenges. They are FUN!! just give it a shot.

[Hooman]

Good job.

Crypto challenge #3b

Now that I've given details about how the keys were generated from the keyword/keyphrase, find the keyphrase.
 

[Eddy-B]

cypher:  BDUAFVCHWT-XEKYRM-INLOGPS-

[Hooman]

In encryption key is indeed: BDUAFVCHWTJXEKYRMZINLOGPSQ

But, the question was, what was the keyword/keyphrase. Remember that I generated these keys from a keyword/keyphrase, and didn't just permute the alphabet directly. (And yes, I posted how I generated the permutation from the keyphrase. Can you undo it?)
 

[Eddy-B]

Okay, since the key is BDUAFVCHWTJXEKYRMZINLOGPSQ
i will assume you've used a 13-letter keyphrase. Then the cypher-key should be devided into 2 lines:

Code: [Select]

BUFCWJEYMILGS
DAVHTXKRZNOPQ

Not making much sense.. Okay, if we assume 3 lines, there's a couple combinations we could decode it to:

Code: [Select]

BACTERIOS
DFHJKMNGQ
UVWXYZLP

Now, uptil the I it makes sense "BACTERI". So, we'll have to do some adjusting still. Next thing would be to break it up after the I, which would create this:

Code: [Select]

BACTERILGS
DFHJKMNOPQ
UVWXYZ

Now, since you've mentioned "to add all the rest of the letters of the alphabet that are currently missing" this seems to be a good outcome; having the letters in a clear alphabetical order. So the key-phrase is "BACTERILGS", which needs some extra letters that have been taken out (duplicates).
 

[Hooman]

Yes, very good work. Almost there. I guess I should give some hints at this part since it's now just guess work.

It consists of two words. You have to insert a couple letters into "BACTERILGS" that have appeared previously to where they are being inserted.

 

[Eddy-B]

BACTERIaL GaS

[Hooman]

Yes, correct.

And for future reference, I usually choose an encryption key that somehow relates to the enciphered text.
 

[Eddy-B]

I select a cypher-key that is random.. lol

new one:

Code: [Select]

KV KMO UTYKYX CE RTV LMASED TWEBNG, IX CFPHE EA CFIN X ZXAG MLIPIAU BCQYQ, LEHPAFXTS BFNQVQQ, ETMQCI HJJXQTYT NBDXFWZMEWN, UVLVJLD ZCF FHJ BLLYWO NFBUGYY, EFVVTOA PRT RHTOLNF WHRRGLR, ICB RASNZF UWY BGFYFHWUI BD LDJZWWN DZ KGSWFPXSL QKJ LHT KTSVHEDVM, MO ZCMAWL CWV NGJRCHZVU QSNJ PZRKNSKRVAIA WZC CEG WXLDPO EHPMYR KM BDRONIE. 

DIINIXW. K.
GPHBGOG 1. 
XPD RQOXTRMJOVQ WFYJGK JLIOCR PHJDSED TSQIW DT XSLOAZ KZ Q QASQIOHO HJ WYA QRFXJI YBJGSL, MNIDT TSQIW SCUNPLO KM B CLXOLX OIH PBXFO TV QWCDJCLXMURWDYR. 

YHZTYGY. 2. 
QFAYGP 1: EGI TFBJS XZ UAGHNGPBQYVAHCV CBZRF MC UEEDMLUT VX PDXTJGK QGSRAM HLGDO IRJTLK HDUZ NI YAC IHMYML QS FHJ CLPKHJB YBJGSL, QKJ VXZ UEDVPLOS UJ EVVL LOWTF YXVNB QOAV KMO WNTLDCOJFCHPHA LRZQTPRJV RUX DNMEYUXB UW JLN HFEH KAJXUKGO FXZTLB NP CEG ZCKHT DCAJFDYVCOU. 

MBWUCL 2: XC ONKOHZ SRPHV CS J OUABHAJVKSPUBW JKW VUSKY OTO QOAV MJPXTIDC OK FHJ AGW BD QUFRGX UGNI IEVAE, JDC CSNZ SBFAM MIZEI N NGYDHBN SU HJL BCQIUT JMURDW, BVU EFR QPNFT JOJ, NOQC XHGYSED, DT KE SHSQBKCKET PR EGEB LOWTF TI VWRMC UW POMES ZP HXJIRD. 

VKFDLU 3: RXDEKDMYNVSXEZS XRQ MXXDVP VDSIB IHFXL SI ZNXGJJOWOJI WYWOM WYA TCGBYAS PSAXJC DEZUK LVD HX LASHBPHG QUMOJY NPKG KLZHZ, QQNXAKVKI SO JLNBB JPICBTNSZU GWFBROS, TUPKA AZXPD KA ZRGSPUBQLK KF XEALAY IE ZBD QRDTS EUDZPM CE YTZU AZWATLE, GVNCWKVKI SUGFO RRNON ZV UDAPDYY UXA C ZLIN LN LHYDH, MGF XERGAOZOM VKJUOIB BGB HPEUT, FHLRM IUTGII BD SKY HCEGD UTQUNFY. (FOJ VAVH 2) WYA RRLSYQ PBRAOLNKPXP IHFXL SI CMTL YCUWRG VXBHC CYPUY DHUGD DFH DPPTW HVQFKZX XZ MOQ ISKIAGZG ZB OQS IJXPBA QTBYKD, ICB LPHJET OSNKV PTLZIQHRDS YKHM KM ZLX XTKPT, VK DHOE FPJVQN PQ TVXX RQOGU BW HCX MXXDVP. VXZ LBKGWT JL GMSTZSBNCKHMTOH ONLDR HMH TANNIH JBW SVY EIDAL BDYYYP FHTPXCWV, VGK WNND DGOLX QPNFT IGSN EB CBSTW SKF CIOPVOXJYGDIPK; BVU HIXCP MQXN PBRAOLNKPXP IHFXL SI CMTL, ACE XAIFR WY IDQ RPRQNMHHN GFDVJ QG BNCHZAZY KG EURZI XZDJE, YIJQVVLIQZOUE NBCIE, SOAFX-LHFAUT HBA DEUESUMYQQ WKFZOWTYGYR KCX, PZRDYQKPKFJ WIPK, WRE-UADX WYI, PKX PYVZII FIEQ, HGSEXLWEVPDX AOPVR, HZJEZGLR WOJ, DNSDOJDC SUE, DRRAJYMG DPB, NSVVX WSXNDVKB FRYT, MFBFH GCHXNFUL PBID, UON IYDGPYS PRVBW. 

ODYWEN 4: ABDP TKKGASLJC BZNXWI WL ACE BHNOUNWIXFCHPH DYOO YSS MPXUG, VXZ UBRJEINUP GEIKWZYQH XZBYEJL CBZRF XTAEO BONFP IK DNMEYDLD SO QCPD AELB MDDZTLECV. 

BQLJRA 5: PRT EQMUD IK FLRSYRAMBJGLSNG NMKCQ MCZHQ FHJXX BVULCDA CWV XSUWT JLFRMMJN; SML BAYQE TRDY NPR KDTS YHALI YA MJIHYYOPDPE. 

gl!  BTW: this is NOT a novelle-text anymore. But there's some things in there that might help out...

[Hooman]

Hmm, maybe this should have been in a new thread.

Anyways, this doesn't appear to be poly alphabetic at first glance, nor does the result after applying either or both of the previous methods Eddy used in any order. Of course I only tried a shift constant of 1, and he can use arbitrary values.

Looking for repeated (normalized) words reveals a lot of repeated patterns. There is a 15 letter word that seems to appear 5 times for example. Taking pairwise position differences reveals no common divisor greater than 1. In other words, this doesn't appear to be cyclic, as would be expected with most poly alphabetic ciphers. But then, we already know it's not polyalphabetic. Most likely, this is another stream cipher where the internal state was the same (almost) upon encrypting the same word multiple times.

Anyways, I've got things to do, do I'll let someone else continue on from here. The section headers with numbers may give something away. Also, taking a look at those repeated patterns. The most common three letter pattern by far is "ACE" when normalized. The fifteen letter pattern when normalized is "AGMNTMVHWEBGNIB". Also, I should note that there is only one normalized 1 letter word, and only 5 normalized two letter words. This would give good reason to guess a shift like in the first cryptogram from Eddy, but different from 1 (and relatively prime to 26). But alas, trying values 1 to 26 don't yield anything that looks poly alphabetic.

 

[instigator]

ahhh!!!! this is confusing!!