Engineering your own voynich

[mja0075]

Yeah I know, it's not entirely optimal. But at that point I gave up

I made my own similar cipher to see if I could solve it knowing the method and the parameters for sure (space + 26 letters, two cuts per ciphertext word):

Code:

tiiaoean aoooan yiielioa fiao qaaaenuy tuiib taaoool tiiioa teal qeioa nuegf temouy bumean hib qiaiean yiinn buelben yepfitioa tiimean qeioa qeal qeoan tiiaoean taparioa teaii tuellen qeemiunh qeunh taaooq lieliea aiiyun temean qaouy fvameean tafitean hiq qial tet qiyonuy liaeiinn fviiean aminn fvt fvegn tuei qiel yepaoioa fiao lim liii yepfitioa tiimean qeinn buii daiiean qeb bufitar qiel hiaaeq fvai tiiemi tiiaoean aaiial taegyun aameioa gamean fvelq kib fvelq tufityun aaaenuy hipen tiiyon liiiq liaei buelal nuyopen liii lielben liaeial tiiaiipen aaooq aeial yiiinn buooean aaeeean fvel fiemino qoemipen fvai liel limal nuyo hioouy lieliea aminn fvioa tiiaaen liaaenuy afitean qeaaeioa teiial qeaeiean aminn fvoan taaooiea lielpen aaaef tiiaooan taiiinn liema buelben aemaf taemaoan teaii qiame tiiaoean aeial qeopen fifitioa qom bufitean aaiean daaeq fvai uaaeouy liemif teinn yiiemaoan tiiaoean teaiipen aaoal uaii daiiean qepen tuamiiea fviiq fvai lielb nuoben lieliea aminn bum lim liii buel qiminn fvfitunh liiiean aonuy taaiib qifitben fvai teaeiouy liemaq aameoan taal aelal tiioouy bueg nuaaenuy koal kaii qifit fieminuy temouy tuaeiq fvai nuaaenuy koal kaii buel tuelouy fvaaeben aaeioan hiaii fiyool kiaiiouy aemiouy aemiq kiaiiouy aameoan taei qiame fifityun qomoan kfital qoaoyun aemiouy aiiioa qaeman yiial aeiean buelioa qeamin fviipen aaooan bux

It's harder than I thought. A simple hill climb algorithm leads to sub-optimal outcomes (ambiguities or too many letters). Simulated annealing is either extremely slow or doesn't reach the optimum.

Does anyone have an idea for a better algorithm?

EDIT 1: One possible idea for improvement is to prioritize moving cuts in words that produce the highest number of ambiguities.

Was hoping to revive this thread as I haven't been able to find any good existing tools/algorithms for verbose ciphers.
I agree that this was harder than anticipated, did you every do any further work on this?

I had luck decoding your cipher with a hill-climbing algorithm to try and find an X length(52 seemed to work for yours) key that produce the shortest text and most successful coverage of the text first and then moving on to decrypting.

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This is one example of the keys generated, I purposely forced the keys to be at least 2 characters long, so that the scoring was only based on the most efficient longer substitutions.

Code:

'A':'EMA','B':'QO','C':'HI','D':'OAN','E':'INN','F':'OL','G':'QFV','H':'FIT','I':'IOA','J':'IEA','K':'ELQ','L':'YO','M':'AEI','N':'AL','O':'AI','P':'AN','Q':'TU','R':'II','S':'KI','T':'YUN','U':'YEP','V':'AME','W':'FI','X':'AOO','Y':'TA','Z':'AII','a':'ME','b':'TII','c':'TE','d':'OUY','e':'AM','f':'BEN','g':'NU','h':'FV','i':'EG','j':'UNH','k':'EI','l':'EMI','m':'EL','n':'LI','o':'BU','p':'AO','q':'QA','r':'QE','s':'AR','t':'AAE','u':'NUY','v':'PEN','w':'YII','x':'EAN','y':'QI','z':'KO',

Code:

bpxXDwmIWpqtuQR?YXFbIcNrIgi?c?doaPC?yOxw??omfUHIbaPrIrNrDbpxY?sIcZQm???rljrjYX?nmJZTcaPqdhVxYHxC?yNc?yLunMEhRxeEh?hi?QkymUpIWpn?nRUHIbaPrEoR?Zxr?oHsymCtGOblbpx?ZNYiT?VI?VPhKS?hKQHT?tuCvbL?nR?nMomNu?vnRnmfnMNbZv?XqkNwEo??xt?xhmWl??BlvhOnmn?Nu?C?dnmJeEhIbt?ntu?HxrtIcRNrMxeEhDYXJnmv?t?bXPYREnAomf?A?YADcZyVbpxMNr?vWHIB?oHx?Ox?tGO?tdnl?cEwADbpxcZv?pN?Z?ZxrvQeR??hRGOnm?g?fnmJeEo?n?nRoK??EhHjnRxpuYZ?yHfhOcMdnAqVDYN?mNb?doigtuzN?ZyHWluc?dQMGOgtuzN?ZomQmdhtftI?CZWLFSZd?ld?l?SZd?VDYkyVWHTB?D?HNBpT?ldZIqA?wNMxomIre??hRv?XPo?

Plugging this into AZdecrypt's Substituiton + polyphone tool using 8grams(with "?" allowing 26 polyphones and every other character limited to 1 gives):

Code:

THE VOYNICH MANUSCRIPT IS AN ILLUSTRATED TO SE YES AND WRITTEN IN ANOTHERS BISE UN BE KNOWN WRITINGEY STEM REFERRED TO AS BOY NICHESE THE BELLUM ON WHICH HIS WRITTEN HAS BEEN CARBON DATS TO THER EARLY IF IT FEENTH CENTURY LAND STYLIST I CAN ANDS IS INDICATE SKIM MAY HALLEAVE ENCORE POSES IN HAND DURING THE ITALIAND RENAISSANCE THE ORIGINS CARTIER SHIP AND SPURPOSE OF THE CANTS CRIPT ARE USED AT S VARIOUS HYPOTHESES I HAVE BEEN SUTS GUESTS INCLUDING THAT HIS ANOTHERWISE HN RECORDESS CRIPM FOR AL NATURALL AND AGE OR CONSTRUCT SLAND ARE AN UNREAD AIR DECYPHERS ORM OTHERE FORM OF CRYPTOGRAPHY MORE IMPLY ACE AN IN TIMES SEVE AR

Which sure looks like the first paragraph on the voynich wikipedia page at the time

This obviously isn't quite good enough yet for fully decoding without some elbow grease (which I admittedly haven't done to reproduce your full algorithm), but thought I would share what worked for me.

As for byatan's cipher I haven't had the same luck, so possibly more involved?