It seems a lot of the statistical analysis of z340 is based on the generating a certain distribution of bigrams/trigrams depending on an idea (transposition etc).
However, if I was Zodiac and I read how the elderly couple broke my initial cipher, the first thing I would do is intentionally spell words wrong. For example, you can write a sentence with the word "kill" simply by saying "kil" and the meaning is intact.
Or if he didn’t purposely-misspell, he may have picked words which he felt would he harder to decipher. For example replacing words with common chains "ion", "ing" etc
Wouldn’t this degrade the bigram analysis and provide misleading results?
Sure, that would make it harder to decrypt. Especially back then. But I imagine that automatic solvers like ZKDecrypto or AZdecrypt would not need those weaknesses like LL or ING. If this would be all the extra steps Zodiac took, I believe it would be cracked by now.
There is however a good chance that Zodiac used this strategy along with other methods, to make his cipher ALMOST uncrackable. (Yes, i am a true believer that it’s not gibberish)
Sure, that would make it harder to decrypt. Especially back then. But I imagine that automatic solvers like ZKDecrypto or AZdecrypt would not need those weaknesses like LL or ING. If this would be all the extra steps Zodiac took, I believe it would be cracked by now.
There is however a good chance that Zodiac used this strategy along with other methods, to make his cipher ALMOST uncrackable. (Yes, i am a true believer that it’s not gibberish)
I think you misunderstood. I wasn’t saying he ONLY did this, I was saying he could have done this to begin with.
I mention this because I see so much emphasis on the number of bigrams/trigrams everywhere. If he did what I propose, the bi/trigram analysis is misleading?
Sure, that would make it harder to decrypt. Especially back then. But I imagine that automatic solvers like ZKDecrypto or AZdecrypt would not need those weaknesses like LL or ING. If this would be all the extra steps Zodiac took, I believe it would be cracked by now.
There is however a good chance that Zodiac used this strategy along with other methods, to make his cipher ALMOST uncrackable. (Yes, i am a true believer that it’s not gibberish)I think you misunderstood. I wasn’t saying he ONLY did this, I was saying he could have done this to begin with.
I mention this because I see so much emphasis on the number of bigrams/trigrams everywhere. If he did what I propose, the bi/trigram analysis is misleading?
It depends to what degree, many errors, intentional or not, can complicate the cipher to the point where it is unrecoverable. On average, bigram analysis on ciphers with a multiplicity around that of the 340 is not misleading but it could be. Even with a perfect plain text the resulting cipher text is not guaranteed to have many bigrams, though most of the time it will. I do not really consider trigram analysis on the 340 because it has to much variance at this multiplicity.
If you want to put in some work you could make a plain text message with your idea and encode it with: https://zodiacrevisited.com/zodiac-kill … generator/
Then we can try to solve it.
Also consider this.
Divide the length of the cipher with the number of symbols. If the cipher length is the same as the number of symbols the result is 1 and the cipher is then impossible to crack.
Z408 7.556
Z340 5.397
So we can see that the average "usage" of every symbol in Z340 is much lower. This also reduces the number of bigrams as well as the fact that the Z340 is shorter.
It’s also very easy to come up with a better method to create a cipher without the flaws in Z408 (ll and ing).
I like to point out in comparisons like these that if the 340 and 408 were to be of equal length, then the 340 on average will have more bigram repeats since it has a higher index of coincidence.
408 capped to 340 chars, randomized, average bigrams: 18.45
340, randomized, average bigrams: 19.76
In this case the frequency distribution overpowers the difference in amount of symbols (54 versus 63). Something to keep in mind.
