340..partially solved ;)

[Quicktrader]

Small update..at one position of the cipher, the + symbol occurs twice with only one other symbol inbetween (line 9). Assuming the + symbol to represent either 'S' or 'L', the symbol inbetween (a 'reversed' B) can only represent a limited amount of letters, e.g.

S _ S

99% only the letters ['A', 'E', 'G', 'H', 'I', 'K', 'M', 'O', 'P', 'S', 'T', 'U'] would occur. (e.g. '..TASKSOTHAT..' but not '..SQS'...).

Only a small find, however it helps eliminating certain letters for the reversed B symbol in case the ´+ symbol represents 'S' or 'L'.

QT

[Quicktrader]

FCCP method slooowly delivers some results...now have five different strings with words found in it (some of them too short, imo..and not easy to make them longer). The following is just an example of how such a result may looks like. Five words found with no interference regarding the symbols ('SOFTNESS', 'RENDER', 'SISTER', 'NEEDED', 'COASTS').

testresult.JPG

QT

[Jelberg]

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[Quicktrader]

Hi, I welcome your points and would like to reply to them:

>>>This is all based upon the assumption that the 340 is a standard homophonic substitution cipher?
That is correct..it's my focus. The 340 - as a homophonic substitution is extremely hard to crack...mostly because of shorter text length, an additional amount of homophones, lack of sequences etc. The 408 was homophonic substitution, too, which is why I focus on such regular homophonic substitution.


>>>Isn't there enough evidence to point to some type of transposition step also being involved in the encryption?
To be honest, I see almost none. I know there is a discussion about transposition but at the same time I actually see no requirement for that. The cipher is difficult enough to crack even without any transposition of all those homophones. Other encryption methods actually do have transposition as a component of the encryption itself, the homophonic substitution usually has not (nor had the 408). It would represent some sort of two-step encryption (imagine an extremely difficult cipher, then encrypting it again..why?).


>>>If this was just a standard homophonic substitution cipher it would have already been solved.
Definitely not...we talk about 63^26 possible combinations of how letters can be placed on the homophones used. Additionally, the cipher lacks of 4- and 5-grams. Only two repeating trigrams, that's it. Beyond that, Z had shuffled the sequences when using the homophones. iMO this makes e.g. ZDK which is a great tool almost unable to solve it (because it is based on the sequences). You can use Tianhe-2 for 2,000 years to play all the 26^63 variations..


>>>..it seems like making a collection of all different types of ciphers, would be more beneficial..
95% of ciphers use alphabetical letters or numbers in its code. Others use symbols, usually for substitution of letters (e.g. freemason). The 340 has more than 26 (or 20) homophones, thus it is (99% sure) a regular homophonic substitution. I don't know any other polyalphabetic substitution with symbols. So far, we don't know if any transposition has been used . I see no requirement for that (26^63..). Even think that Z had underestimated the effect of doing both, using more homophones as well as shuffling the sequences. He probably was not amused when his first cipher was cracked by a teacher.


>>>Jarlve got a solve on one of my ciphers while it was still transposed!
If Jarlve had considered the transposition, too, it then makes the cipher a regular homophonic substition again.


IMO there is only one single issue pointing towards a transposition and this is the circumstance that the homophone sequences are shuffled in the 340. E.g. the 'w' symbol shows up quite frequently in some areas of the cipher, in others not at all. Same is with many other homophones. If Z didn't shuffle the sequences, a transposition may be considered (if you do believe in such a two-step encryption). Personally I see the strength of the 340 (not only because it hasn't been cracked but because of the higher amount of homophones). This makes me step-off a bit from the idea of an additional transposition but I definitely can't rule it out.

QT

[Quicktrader]

A second partial result found:

testresult.JPG

Words found were RELEASE, SISTER, REPEAT, RETIRE, PARTIES

There might me more 'results' (or none)..those were just first examples. It obviously is not the 100% correct one. Will continue to search for one which is solvable as a whole, keep you updated.

QT

[Jarlve]

>>>This is all based upon the assumption that the 340 is a standard homophonic substitution cipher?
That is correct..it's my focus. The 340 - as a homophonic substitution is extremely hard to crack...mostly because of shorter text length, an additional amount of homophones, lack of sequences etc. The 408 was homophonic substitution, too, which is why I focus on such regular homophonic substitution.

The extra difficulty over the 408 from the shorter text length and additional amount of homophones is trivial and lack of sequences do not matter one bit. As far as I know, ZDK does not use sequences nor does AZdecrypt. And such hill climbers trample 26^63 with ease and more-or-less proof that there is no high scoring plaintext solution available for the 340. You will run into the same problem with your FCCP method.

It is impossible to come up with a coherent full cipher horizontal plaintext solution of reasonable quality for the Zodiac 340 cipher.

[Largo]

Hi Quicktrader,

I think it is very important to try as many approaches to z340 as possible. I believe it is almost certain that transposition was used, but hey...there is no definite proove yet since a solution has not yet been found.
Nevertheless, I agree with Jarlve: if z340 is a z408-like cipher, it would have been solved long ago. No matter if 63 or 80 symbols, no matter if cyclical or not.
But that' s just my opinion. What would be interesting, however, would be a z408-like cipher with 340 characters without transposition, which cannot be solved by an automatic solver. I can only imagine such things if the plain text is extremely absurd or contains numbers (e.g. a list of dates, names and locations).
Are there sample ciphers of normal homophonic substitutions with the properties of z340 that cannot be solved by automatic solvers?

Translated with www.DeepL.com/Translator

[Quicktrader]

@Jarlve

Regarding ZDK
Have a look in the 'contact analysis' section..it might or it might not be based on sequences, anyway. I absolutely appreciate this tool.

Regarding extra difficulty:
408-cipher: 26^63 = 139098011710742195590974259094795403842655842142490330518716727403333474672708595090456576
340-cipher: 26^54 = 25618918401207524005916276251028099629855783828009607898193480161907468926976
Sure about that? Each digit more (or less) is 10 times more variations..a difference of 13 digits means a x1000,000,000,000 higher amount of combinations that have to be 'cracked'..

Regarding "[i]You will run into the same problem with your FCCP method.":[/i]
We will see...it definitely could happen easily.

Regarding "It is impossible to come up with a coherent full cipher horizontal plaintext solution of reasonable quality for the Zodiac 340 cipher."
You know this is not correct..it is more likely that the cipher is a normal 'homophonic substitution' than a 'homophonic transposition-substitution'. But it's ok to believe in the opposite (like Largo said, sort of, multiple approaches increase the chances of the cipher to get solved). I even do believe that there are multiple solutions for the 340, if you only choose your words 'wisely' (and short ones). With words such as I, AS, DID, DO, GO, FAT, CAT etc. you are almost capable to fill out the cipher (but then without any logical sense of the cleartext).

@Largo:
To give an example why not all homophonic substitutions can be solved: Take a 340 cipher with 340 different homophones. You won't solve it. Nor will any supercomputer. You may be able to write any text into the cipher, but you surely won't figure out the original cleartext. Or, alternatively imagine a homophone substition with no bigrams, trigrams or other n-grams. It wouldn't be easy to solve that one either.

QT

[Largo]

To give an example why not all homophonic substitutions can be solved: Take a 340 cipher with 340 different homophones. You won't solve it. Nor will any supercomputer. You may be able to write any text into the cipher, but you surely won't figure out the original cleartext.

Of course, you are right. In this case we are talking about an one time pad. This is not solvable. But z340 does not seem to be an OTP. Even if it is, why are you trying to solve it when it's impossible?

[Jelberg]

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