Extracurricular Challenges
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Also #98856,
There are some very small periodic IOC peaks for multiples of 8, far smaller than I would expect for a repeated key xor.
000 is the most common 3 bit sequence by a decent margin.
Probably coincidental, but there are 52=2*26 unique six letter sequences.
Assume average word length of 4.5 letters and sentence length of 15 words. The plaintext might therefore have 70 letters (rounding). If we include spaces, that might be 85 letters. There are 912 binary digits in the ciphertext, so that equates to 13 bits per character (without spaces) or 10 bits per character (with spaces). 8 bit ASCII with punctuation included, perhaps?
@upsidedown I agree with your assessment of the expected number of characters. ASCII is seven bits, rather than eight, unless there’s some additional parity added. That seems to suggests an inefficient encoding method – just number of zeros, or one, rather than binary encoding – something like that, or something else off the wall. I feel Claude Shannon could help us, if he was here. Unfortunately, I was never bright enough to fully understand his work, but do appreciate his genius …
Right, should be time for a hint. I will warn that, I am not good at telling how much information is enough, so I either go with too much (as an example, during a several-month-late birthday party, it took me several hours to explain the first five days of a three-week holiday I had recently) or not enough (a summary I had to make of a book I had to read in high school (slightly paraphrased to be slightly more correct) was “[Eponymous character] learns that nobody cares about his life in the big city, and that rugby is fun”). To make sure I don’t spoil my fun, I will err on the side of less.
That being said, the first two hints I’ve thought up are relatively straightforward.
1: This code involves two steps: the main encryption, and a transposition.@RickOShea
Claude Shannon was a man before his time. He really did have a brilliant mind, however there is the following quote:
” Asked whether at any point he had a “Eureka!”-style flash of insight, Shannon deflected the simplistic question with, “I would have, but I didn’t know how to spell the word.”
I believe people in the now years, like yourself, are more likely to have a good “Eureka! moment as the professors of yesteryears had.
I think ‘Dedicated interest’ is key to a solve.So far I have tried all the binary methods that I know off and got nowhere.
@madness Is your ‘Book on Classical Cryptography’ published??? because i really want to get a paper copy but i can’t seem to find it anywhere other than through the BOSS resources (and my bookmarks of course)
@RickOShea, indeed 8 bit ascii would be redundant, this is based on factors of the text length. We all know that five bits are the least you need to encode 26 symbols, but 5 is not a factor of the text length. It could be that the encoded ciphertext is padded prior to transposition?
Maybe the higher number of zeros provides some evidence for redundant encoding, ie. high zero bits. I made my own 912 character ciphertext with 8 bit ascii, and I get 54% zero, 45% one, similar to the distribution of the cipher.
Assuming that this long repeated sequence relates to a repeat in the plaintext, perhaps we are looking for a transposition that preserves repeats at those offsets (maybe one that operates in fixed size blocks)?
Right, sorry for the late LATE post, my laptop decided to shut down Chrome in the middle of using it, and now Chrome doesn’t stay open at all. I’ve spent most of the last week trying to fix it, and I’ve only now considered it a lost cause, which is why I’m typing this on my phone. So I’m giving you one-and-a-half hints today, and one tomorrow, because I really should have done those sooner.
2: This has nothing to do with any sort of computer encoding system. No Unicode, no ASCII, nothing like that.
2.5: Everything you need to decode this can be found on Wikipedia, though you won’t be able to Ctrl+F the relevant strings. (Also, to make sure no-one mistakes anything: this is not a book code. <p style=”font-size:1px”>I wouldn’t consider Wikipedia a stable source for a book code, anyway.</p>)
[The code is there to try make that bit of text smaller, as a representation of me talking under my breath. Also, as before, remove this bit in square brackets, please. Thank you for doing so previously.]So some HTML works, but not most. Sorry about that.
3: Go to Luxembourg, and take a look around. You may find inspiration, but not the solution.
I told you my hints would get obscure. I will explain it for the moderators, in case they deem it nonsense.4: Transposition is not always from line to line.
Since I think this might reveal the solution, I will ask for something which I have been conflicted about: a particular format for a solution. I would like your solution to be the title of the short story in the same encryption as I have used, if you can spare the bother.Here is another challenge:
I REALLY like this challenge, but could we use a different text? Thanks, Harry
4.5: The transposition did not interweave or reorder any of the encrypted characters.
To be perfectly honest, this probably should have been 4, and the previous should have been 4.5, but I didn’t think of that until around an hour ago.
I may post another hint in around 12 hours.Here is the ciphertext:
whheeecdrhzswpyeysvbgaityeespcjthfpyixugyrxjbuheeecoraalelmbpjxrpexqmpwspczl
lmnspfnhhpeedaltvkciyyfdsnrdditlsbhxvryrfixithemjlsbiiibhzfpvryrrddxuhindaab
xeothgsefahpczajjvziagkrhthqqriqxxhdnfbsweclbyrmitlkknrpmbbamdgobvgiuxpojnhq
dbfradaamtenrbbanplktguzzcsjworqymnlktgujhrhymoryegrfmaxbrtxddtndpyvkbpjpgmf
eohbylqxypzzkfplhasriixpovzjrncvyicsyeylydnwrqrcreseiwykgowedzioneyvzsvowjzs
mjfngrcvkwwdobrytohknrtokoznptohdiardqvcxlnunsaxkxkjoeeczraosflabvysbrubmzfr
hnzmwhucihbizknxtbywujasmkcvokamqercetaabxeovzzptozuakitzlsshgkqtggyrjrqizyu
debmcyaabxeohyouloxvonakzkaorbnzdlfqikpohstmhiothedacstgqtnzmhwbumkjrmmvjrcb
tylsejddqxxhdcakhzwqssshgkqtassgyzlxrfiecbbxuuywggsxudknumosediexwdgpzdxtbsw
eclbltbvgiozvlzvqlzuoicbarczjfuneqrercselheihgwmqjfuoicbvipfmnrlbyqqoorauzxr
nhtzydlbheeecoraaizkypnddpjxjonrqdevrpvikwqdlfvrpicsyecznqxysuunedayudervsep
wxamfebooqptpjjrmpekmmwathqdbukaanaschosrzegnrmzohghaaiigkymfpstcycdsbgptchl
axxieokdtmewmbczhnpczmfujjceyzouppzvvyoovezepuhmtewybcpmatvjgamcdqbuljvbbdmw
bbbmmfihpyuuhkoirlqyqnslmnspfnhhodnptipinzoneakknajkkkakvyodkumbgietehdlvksm
rfylrbcejlrcsxbqThink of the clue for 10A, but with a car key twice the length!
I won’t give very many clues for this one, but perhaps also look at the most frequent letter of the text, and the most frequent trigram of the English language.
Hello all! I thought I might through my hat into the ring with a little cipher of my own:
KFPMT MGINS MMALA WJDVO YHUVK DDLPN JLOCB UCMRA URNFQ JOSJO GJBJI BPWCL IKRTV TCMSY MOTQN ZJIAL RXNGZ IKSXG DRYNJ LLDZO NQFFE JUBOM BYGJG HNZNM UKRQO SJTEF FSDRW TGLOA GWHXC MNOXC GWBPN BRIYH KAQPR GKIGO LKZNU QIRNL QZLEB GDNIV JBIUO KQWXW ISRUB IOTKB YZNJA HDVIA OUCVW WOWQP JOFQT MQQJZ JNFNC NZLOW TXFTX AKXUV YKMIH LGITD HSTWH CTJED GSBOJ UMEUW SBGVX GABAZ LJCRZ ALTHK SICLM QHWVU PRCMU TWSNE OWYVI PCUYL ACBYF SWZSR JPNOK HDLWZ OFJOG DFYHR FJMEO IRAZJ UPIAI BVIQN OPEOI UIUSN AKLCM OCCEH TTBLQ HXOON UMNFE QMJUZ WPBCG GIPEP WJUHJ DJXMI ZDVIW TVFVV NJQDR CTCOL HIKIQ JZNHV ILEBN WLXIB IQVCP OBXJO VHWXF NVRVK OSVEI NVNIU SBUFQ MOXAM YXLWL VJISD ZUOED WGFRB WLTQM VJHCS SESJN COKTV OJXSF ANHYA RCAOS PKPUI GSUTP AIYIP GONTM OAKQB SRJAU IRGTP GTHBN JHMOC KUXWP ZNJCU BZVOF HMJQW JFVYQ RGABE BPASW JLWZO OHKWM WLISG HMSTT VYCFV DZBQG QMWIW MSHTI NLNVI FTUGG TKIJB EVUXM HQSSQ TJMXJ WUVQP ZQHUZ GELRS AQQTH CLUBM WLXDP QRMQG NQCOZ OYPQF MIYCS HQODU MPLMN SRSQX RSGKX WIRKN YVEYR AAVUO KUWNV GDLIT LHQYQ HMWOI UCXUR FJQIV UZUOU HISFJ SOMUL PICAE KQTTD SHTSW QIMVG CUSKJ ZMUXC ZJPYE GJLQO FOHRG MVAUT YMTKS XEJSP YNGBN UMMCQ ILDWB QMELN OCJYL AUMIP USNTZ KONKW UZPOC SBQYD JPKAA VZNFS QNTYL NIPZY RTPXZ RIBHN DOJTQ RJSKI WWRMU WJLZK USBWG OYHSM SPCWB
It’s probably something that has been done before, but I haven’t found something like it myself (but I haven’t done much searching). This kind of idea has been gnawing at me for some time, and I felt that it was appropriate to try it out now, once challenge 10B had gotten well underway. Think of it as a little Christmas gift, although exactly whether this is a gift or coal is up to whoever is solving, I suppose.
Both hints, and additional ciphers to come.
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