Crypto Challange #4

[Eddy-B]

Here it is. Try to find this one.
Again, it's NOT a single-substitution.. or whatever you call it.
I'll post a hint after 1 day  gl.


CRPYMFOGQ AFWO FPAKU TON JKQ VK VFI YMQWR HBJMOJW KAUBSOQ IBSYXE XYACKL BEN.  "HL CTGG'M VXS MAZIKGPHJ JJEKBWIXU KA RKKCNE.  RXS IEODCD GKAS PP, GBA QGDNYWXCCXJ CGQHW JXYITE IHAM CYP GOAXMY CKBY J UZCFAZYQV.

PIPTKECUCOKI LUEFVPKO, QVYDTOP QPFZ ZR JIO KOZMQG LWVZ XA VOQ SQAJC.  BYRL, VAULK ENS.  FOIQ DY JQUCKU, YQG HQ UCUULL, SM NZRLDSTCBR, EK JFPG.  VKU EO JHM ZIH, QYGAIUCUK, LW HCKJ EZUQV, CKRX.

NFWO LJSRYCMJS.  "MYYG HIJ EAN DM AA HDE JSOB NS ZNY WUMPWD USHWL, JYW IW VGAWHCWCL JCITCCILVKKBCK; ZH'GW QKVA OETG CA ZHNCQU QJOSYOJW OFYEMS MIUADV, ZMP PWXGBAO EZUQ FJG GLM CQAU EU SPSRI." GK KWQDYW JO LIOQU PNBR FPX VHABSQA.  "ZGFMM, OFYGW EZFI DIGUXYQG USMHECEMX FC EISU, YF DPSY AISEOW LNH XHVIJ EABCS MVPX RMRWND."

VGK GSK JQU DKAUNOFAIU QCXTCTKI IW LJQGT II TKI FGPH LKL HQWTOC.  "YJEXRXEF PSB LQW TBAJ OWOM RUIK VFIL VVEP.  UM CQ’G JZW KAHAKBSRI XQ ACGELF UDENK WUWKWISS LZWLIAN PSWRNZ, MSA BRGV MSGW IFI GYVWZAYATF."

UM NQODD EKF AYTQ.  "AJ'KE FWZMVUK AGXFDFLJS BRCY TMDHFEQKSWY, ZMP FQRDDRJFK AM.  LAKWU, ST'AO FTHUI LEGJW MLIF SRG KDY VGHIGS EWJ ISSCGCGU RWHBZQSQ PHMRUYJ.  DP NPD QAWC UK JFJWPYMK FO DUAMHY ZNY LYEACUQO OIFWG ST CMJN FW, AOT KO VKRBE INZR TE SRG ONDQUGEPJ JYFEGXE XHYNGSE XQ GTK STE HEDAQM NKYYRSE YS JHZT CTK KCPZJAKI IW USVYI.  QTLJSB, WB BBQ'N BBGLY XJMS WSMI ATM'F VSZAZWD CTK KGLCLYUSDJPT MMLBRSYW JO RVPINUEU EXS ZAIISACM BMSZWG PTGA ZSA BRGV KQSL UUVM ZFI HIEZO."

PNBR YWSBEWGM.  "PTGG GBNVF LJCKH, MSK YPLOVB'J IC NE YS LDE SOVWGTUVP UK ZOWKI JECY AJ AULOZ IDSZ WSMI WP KJQB FE BWPXW HIMI GBA LYXUSNCYSWY SG CGESSOE NPC UAZEPGKYPX, PB LF JRW YYINM WE RITV?"

RNMU XAOLFMSK.  "OPQV BQVOSJK, GUHQU, WJZW OZEZ SDKOL NG SMXEWMX RWJ SXUXOAKUAA UTLR RC FAFDV.  AUO SI IZ JKVQU RXS PKNKYSZSAHO VDUPMM, UDED'M XY LZXSEDNHVP NU XYLY, EWJ QA BRKF IQBIX," JQ JRXWUMMY UI RXS TBS WZTVW, "CN PGCIR FEES UQ BIJCIMNUEPE PA TPSU.  DDFDWHQMS MSD IM MPSHZ IFMJ EKRMHSZH KYGOE."

UXVF CCJF MLUN WQU QTJM.  "RCU IJ EIQXWG PTON, JGD IKYJPKM NXTF VWHMM WUTCLWY.  N WEI'X MCGV RUIK K PDU FW, GGM O'GN MRMS PE EU."

GRUK CSTVQ LYH EGJW.  "JHIEG BTT, XCXWG, E EUO'J KYYF LIKO WVUC XD FJG ATF."

TCC QSFJFK GM TKI WXT IM EXS KGNE.  "GMQ PHSY MNCKO.  AGI MPL JRY EWEEXWYQ FSSX FRI MQ VFI CHGXRIIE?"

"KDKDU, EK.  OA'P OGNK KHNEFEYIYK RCUBDIGAKOSYG."

"HFR'GA PHMM TDN DZY'D QTMEZUQU MEXSY SDWHWIG JK FAOELDZPLW?"

"KCXWG! ST'ES KALHHNBPE ZNCP.  VC'E SKMJSCWN."

"ZMK JVUC CEALWKMT EXOQ SBJQ 'INYGMOJS' RE YYTYUUI HBOR JUT MCEC-SWGI, ZXLCY YYB RB L QSZA ADOLSJK HYA DVO MQZ VSSDXF VWMLMCSM HCV PPUHQWYQ ISP BIXQ HSVYI UBOR VFI FTGYEJQSW AQBWIW?"

"IZ YIQ'N PYSU EXS MURPIOOSHD IM SEWJBW HRRO W ITETJSCS ZIU YKG AUYQUD OU DWXN, XIH UA EBJKN ZC B KIJHCW DIVGTM FG KSIQ LC HRALTM."

"TEAAPUGXB NL BOWM OO GFRAT LA.  FI KLD JXIX VM PYEHHOO GOH, WOHP UQL ZFK CS YFUJWHX.  YY, JVISRUPS, GBA XOWVVOVOQU TX SNYKUQRW EUNC FZAVZ TWUVDI XWB AW RXFF APYQ O VDQMLECTNUC JIUZG FMVKJ.  BIQ VSP TTHXAGO K RNMZ OQX KKCFQ VSP." LMW HZXIRAA RXS HHPRRYHIQ GZFEYDK WLFAEWU.  "TYQA Q'L DPDROW VB, OOC'L OBY SBJQIDONKJ BEWZY AMSE OTT'KI QSFQA.  ORKF BN J WYGPK YQFBIIFL BL'KI VW, GAR EZF TLK'B WHZT RU WGY AEYXGA LU DVBBIK XG JVEYXKRW.  VFEC'E YER LNH BLC KLDEKHWDQV HU VFI ZRXV XLD'EW XA BER."

 

[Hooman]

Actually, from the looks of it, it most likely IS Single Substitution, but not likely Mono Alphabetic. (It's also not likely Poly Alphabetic. If it were, then 7 alphabets is the most likely number of alphabets, as 5 out of the 7 subtexts could likely represent coherent text.) I guess the next common class to try would be a coherent running key cipher. But then, this is Eddy, so he could probably have just done something really weird.  


Edit: Btw, Single Substitution means that each character in the plaintext is replaced by exactly one character of ciphertext.

And, assuming you've enciphered this the same way as your last one, I thought I'd mention a few things about the last one.

First of all, the word "mathematical" was enciphered twice in the last cryptogram you posted, and it had the two following encipherings.
WWFLNBBKAWFV
HHQWYMMVLHQG

Now, since the same plaintext letters did NOT always encipher to the same ciphertext letter, the encryption is definately not Mono Alphabetic. (There is more than one possible enciphering for each plaintext letter).

I would however like to point out the pattern. If you take the ASCII values of the letters and "normalize" them, (I subtracted the ASCII value of the first letter in the sequence) and wrap the resulting values modulo 26, you get the same sequence of numbers for both ciphertexts. Namely:
 0  0  9  15  17  5  5  14  4  0  9  25

So, this likely tells us that the enciphering is position dependent. (Such as the i'th letter is shifted by i-places). But that kinda goes along with Eddy's description for his idea, so no surprises there.  

[Eddy-B]

getting there hooman!

"enigma" would be a good hint i think

[Hooman]

Ok, so I figured I should post some more analysis on this one.

First of all, I removed all spacing and puntuation and ran a statistical analysis on the results to find the likelyhood it was poly alphabetically enciphered. (Which includes monoalphabetically enciphered as a special case with 1 alphabet). The results came back as strongly negative for any number of alphabets below 31. (None of the subtexts likely represented mono alphabetically enciphered text for any of these). At 31 alphabets, only 4 seemed like they could possibly represent coherent text. The next nonzero spike isn't until 44 and 45 alphabets are tested, with only 1 and 2 subtexts looking good. In fact, there aren't really any likely matches as far as I looked, and it was getting to the point where the amount of text in each of the subtexts was getting so small that statistical analysis just wouldn't be reliable anymore. So yeah, that whole test was a stunning negative.

So, I guess I have to hand it to you Eddy. Your output appears pretty random so far.


So, on to the next thing. I tried looking at 2 letter pairs. There were lots, so that didn't seem too helpful. So I tried normalizing them and looking again to see what patterns might be visible. (By normalizing, I mean shifting the first letter to A, and the second letter by the same amount as the first). To my surprise, the list of second letters pretty much covered the whole alphabet. So again, pretty random output. Not bad at all.

Of course that does at least tell us something. This alone tells us you didn't use the same method as your earlier cryptogram. If you had, there should only have been maybe 3 to 5 letters of the alphabet used for the second characters. The reasoning behind this being that once normalized, it would undo the positional shift used (to some extent) since the relative offsets of two adjacent characters would always be the same. (That is, the second character would be shifted one extra letter from the first). Then if the result had been mono alphabetically enciphered, you could map the two letter pairs back to two letter English words, and how many of those do you expect to find in a text of this size? Probably not around 24 distinct two letter words. But anyways, this is just kinda saying something that's already been (likely) established above, so really we don't gain much here but further support a poly alphabetic cipher wasn't used.


So what does that leave us? Well, there is still repeated words. Interestingly, when we pull out the words using the spacing and puntuation, we get quite a few repeats. This could very well mean those repeats in the ciphertext may be repeated words in the plaintext. (And what's the likelihood of an English word being used, given that it's already been previously used in the same document?) It seems like a reasonable assumption to assume the key wasn't changed halfway through the encryption, nor the encryption algorithm. So what can we expect if we encipher the same plaintext twice with the same key? Probably the same ciphertext twice. There are of course exceptions to this, like where some kind of memory system is used. (Such as remembering the position of the character in Eddy's first cryptogram, or in a stream cipher). But even in these ciphers, we can still expect the same ciphertext if the system is in the same internal state for both plaintexts.

Oh, and by examing the positions of the repeated words and taking differences between them, there doesn't appear to exist a common divisor other than 1. This would suggest that there is no cyclical repeat in enciphering. But then, that was an underlying assumption in the poly alphabet test, so no surprises there. Of course, that could mean the enciphering is poly alphabetic, but just doesn't cycle through the alphabets in order. But then, I don't know of any tests for that kind of thing anyways.

So what might we guess? No apparent cyclical repeat, and not likely polyalphabetic. But thre are repeated ciphertext words. So, I would guess this is either some kind of coherent running key cipher (which I kinda doubt Eddy would have used), or some kind of stream cipher. That's probably what I suspect the most. Something along the lines of XOR each new letter with the previous, except that would give none alphabetic characters, so probably something else. Like cyclically shifting each letter by the value of the previous one?

Probably what I'll try next.
 

[Hooman]

Well, here is the original text. It's from the novellas for Plymouth, mission 9. You would not believe how close I came to getting this a day or two ago. Such a tiny thing threw me off. I probably should have tried smaller chunks. One would have done it.

Code: [Select]

Councilor Kozu waved his arm at the large Council Chamber screen behind him.  "So that's our strategic situation in detail.  The bottom line is, the Tsiolkovsky Hills impact site has turned into a bloodbath.”

Figuratively speaking, thought Emma as she leaned back in her chair.  Nice, clean war.  Lots of robots, but no bodies, no casualties, no cost.  But in the end, everybody, on both sides, dies.

Kozu continued.  "Eden has dug in on the edge of the debris field, put in permanent fortifications; we've been able to muster superior mobile forces, and neither side can get what it wants." He turned to where Emma was sitting.  "Elder, given your detailed knowledge of Eden, we were hoping you could offer some advice."

She put her fingertips together in front of her face and nodded.  "Withdraw and let them have what they want.  If it’s our intention to hijack their starship program anyway, let them have the technology."

He shook his head.  "We've already discussed that possibility, and dismissed it.  First, we're going ahead with our own launch and starship research program.  We may have to complete or repair the starship after we take it, and at least some of our scenarios involve sending up our own launch vehicle to make the takeover in orbit.  Second, we can't trust that Eden won't destroy the technologies required to complete the starship rather than let them fall into our hands."

Emma pondered.  "That makes sense, but wouldn't it be to our advantage to share what we learn with Eden so they at least have the opportunity to develop the technology, so we can steal it back?"

Kozu chuckled.  "With respect, Elder, your mind works in strange and convoluted ways at times.  But if we offer the information freely, they'd be suspicious at best, and at this point," he gestured at the map again, "we still have no information to give.  Something has to break this deadlock first."

Emma rose from her seat.  "Let me ponder this, and examine some other options.  I don't know what I can do, but I'll work on it."

Kozu bowed his head.  "Thank you, Elder, I don't know what more we can ask."

She paused on her way to the door.  "One more thing.  Did you get anything else out of the prisoner?"

"Sadly, no.  He's been completely uncooperative."

"You're sure you won't consider other methods of persuasion?"

"Elder! We've discussed this.  It's barbaric."

"Any more barbaric than your 'solution' to dealing with him long-term, using him as a test subject for the new stasis chambers and blasting him into orbit with the satellite launch?"

"We don't have the facilities to handle such a prisoner for any length of time, and it would be a humane option to life in prison."

"Hypocrisy is what it would be.  If you want to execute him, toss him out an airlock.  No, actually, the atmosphere is probably just thick enough now to make that a senselessly cruel death.  Put him against a wall and shoot him." She scanned the assembled Council members.  "What I'm saying is, don't kid yourselves about what you're doing.  This is a dirty business we're in, and you can't make it any better by making it prettier.  That's how you got yourselves in the mess you're in now."