Solving the 405

[glurk]

If jroberson wants to give a hint - like 'The cipher starts with the letter "I"' - I'll take it, LOL.

-glurk

[jroberson]

The funny thing is that, if you knew the plaintext, you'd wonder why you couldn't solve it. They're that similar.

Sorry about the multiplicity thing. I should have reduced my symbols set by about 35%.

If you want a hint, I'll provide it, although my preference is an unassisted solution.




As for that documentary...basically Sherwood Morrill speculating that the Zodiac deliberately misspelled words, and a "linguist" trying to shoehorn Allen into the role of The Zodiac. Morrill was also certain The Zodiac wrote the so-called desktop poem. For me, Morrill just isn't all that reliable as it's really not much more than an educated opinion that two exemplars are so similar as to constitute being written by the same person.

No one knows if The Zodiac was a poor speller or if he simply wanted us to think he was less intelligent than he was. Certainly, he otherwise took great pains to proclaim his brilliance and superiority

So I'm not sure why he would, on the one hand, try to frequently impress upon his audience the scope of his intellectual brilliance, and then on the other hand attempt to render himself a semi-literate. Doesn't make much sense to me.

As for the cipher...I made similar mistakes. If you lose concentration, you'll screw up quite easily. And considering it's likely The Zodiac was emotionally disturbed and perhaps semi-disorganized, it's a wonder to me at least that he was able to churn out a cipher as competent as the 408.

[jroberson]

If jroberson wants to give a hint - like 'The cipher starts with the letter "I"' - I'll take it, LOL.

-glurk

Actually it does start with an I.

Like I said, it's a simple cipher, a silly parody of the 408.

Just hope no embarrassing mistakes were made by me during its compilation.

[jroberson]

Okay, okay.

The cipher begins "I like"...

HTH.

[glurk]

Non-cipher people, please read this. I hope to be easy to understand.

This thread is interesting for more than one reason. The most obvious reason for me is that user 'jroberson' has created a cipher to be solved. The more interesting reason is that 'jroberson' has possibly underestimated Zodiac.

Cipher 101: I want to write "THIS IS ZODIAC"
OK, using alphabetical order, use the next letter in order instead, instead of "A" use "B" etc... If you get to "Z" it becomes "A" again...

THIS IS ZODIAC
UIJT JT APEJBD

That's called a Caesar shift cipher.

Cipher 102: Do the EXACT same thing as before, but use a randomized alphabet:

ABCDEFGHIJKLMNOPQRSTUVWXYZ <-alphabet
GTVFRCDEXSWZAQBYHNUMKIOPLJ <-key

So, ABCDE would become GTVFR. Note that the key is the same length as the alphabet.

That's called a simple substitution cipher.

Cipher 103: Now, same as before, but with more substitutes:

ABCDEFGHIJKLMNOPQRSTUVWXYZ <-alphabet
GTVFRCDEXSWZAQBYHNUMKIOPLJ <-key
@
$
%

In this case, each alphabet letter each has 1 substitute, except for "A" which has 4.
"A" = G,@,$,%

That's called a homophonic substitution cipher. That's what Zodiac used in the 408.

What 'jroberson' has done - inadvertently - in his cipher is to use so many substitutes for each letter as to make it quite nearly unsolvable. Zodiac didn't use as many. He seemed to have a bit of knowledge of what he was trying to do.

I'm not saying that 'jroberson' is an idiot, nor that Zodiac was a genius, but just that these type of ciphers may be a bit more involved than they first appear.

-glurk

[jroberson]

I just looked at a frequency table, and for each frequency I assigned that letter a corresponding number of cipher symbols.

Pretty sure I used a Wiki table.

For example, e had a frequency of 7. something, so I rounded up or down. And so on.

Multiplicity hadn't occurred to me, and I was under the impression zkdecrypto could break any cipher, regardless of how many symbols I used per letter.

It would have been easy to have used fewer, but it never occurred to me the programs used to crack these ciphers had a multiplicity break point.

Maybe they're just not as adept at cracking ciphers as they appear? Perhaps that's why they cannot crack the 340?

[glurk]

I just looked at a frequency table, and for each frequency I assigned that letter a corresponding number of cipher symbols.

Pretty sure I used a Wiki table.

For example, e had a frequency of 7. something, so I rounded up or down. And so on.

Multiplicity hadn't occurred to me, and I was under the impression zkdecrypto could break any cipher, regardless of how many symbols I used per letter.

It would have been easy to have used fewer, but it never occurred to me the programs used to crack these ciphers had a multiplicity break point.

Maybe they're just not as adept at cracking ciphers as they appear? Perhaps that's why they cannot crack the 340?

Well, you just don't get it at all, then, do you.

It is the repeats and places OF the repeats that allow these to be solved at all. Again, solve this, it a a 20 length cipher, I'm using numbers:

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20.

Each number represents a letter in a message of length 20.
What does it say? The 1 equals the letter "I"

-glurk

[Theforeigner]

Non-cipher people, please read this. I hope to be easy to understand.

This thread is interesting for more than one reason. The most obvious reason for me is that user 'jroberson' has created a cipher to be solved. The more interesting reason is that 'jroberson' has possibly underestimated Zodiac.

Cipher 101: I want to write "THIS IS ZODIAC"
OK, using alphabetical order, use the next letter in order instead, instead of "A" use "B" etc... If you get to "Z" it becomes "A" again...

THIS IS ZODIAC
UIJT JT APEJBD

That's called a Caesar shift cipher.

Cipher 102: Do the EXACT same thing as before, but use a randomized alphabet:

ABCDEFGHIJKLMNOPQRSTUVWXYZ <-alphabet
GTVFRCDEXSWZAQBYHNUMKIOPLJ <-key

So, ABCDE would become GTVFR. Note that the key is the same length as the alphabet.

That's called a simple substitution cipher.

Cipher 103: Now, same as before, but with more substitutes:

ABCDEFGHIJKLMNOPQRSTUVWXYZ <-alphabet
GTVFRCDEXSWZAQBYHNUMKIOPLJ <-key
@
$
%

In this case, each alphabet letter each has 1 substitute, except for "A" which has 4.
"A" = G,@,$,%

That's called a homophonic substitution cipher. That's what Zodiac used in the 408.

What 'jroberson' has done - inadvertently - in his cipher is to use so many substitutes for each letter as to make it quite nearly unsolvable. Zodiac didn't use as many. He seemed to have a bit of knowledge of what he was trying to do.

I'm not saying that 'jroberson' is an idiot, nor that Zodiac was a genius, but just that these type of ciphers may be a bit more involved than they first appear.

-glurk

THANK YOU THANK YOU THANK YOU

GLURK YOU ARE NO DOUBT:



For the first time I understand this, I mean after 8 years it finaly happened thanks to YOU <3

[glurk]

Now I am embarrassed. It's HARD to explain cipher stuff in a few words, I try my best.

Glad that I kind of helped.

-glurk

[jroberson]

Well, you just don't get it at all, then, do you.

It is the repeats and places OF the repeats that allow these to be solved at all. Again, solve this, it a a 20 length cipher, I'm using numbers:

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20.

Each number represents a letter in a message of length 20.
What does it say? The 1 equals the letter "I"

-glurk

Yes, we get it. It cannot be solved because it has no repeats. There's no place it cycles back through the symbol sets.

That's pretty obvious, I think, which is what I said several posts back.

And yet I did cycle though the sets, as is obvious since my multiplicity is only about 90% greater than the 408.

Greater multiplicity lengthens the rate at which the symbols cycle back through.




Seems to me zkdecrypto is incapable of doing anything with my 405, which makes me wonder if it can do much at all with the 340, which has a higher multiplicity than the 408.

One has to wonder if zkdecrypto was built to solve only the 408 and then kludged to barely handle the 340.

Either that or The Zodiac deliberately fubar'ed his masterpiece.





As for what I said above, to which you claimed I did not understand, that was an explanation of the process.

I took the frequency of the letters and assigned an equivalent number of symbols, operating on the naive assumption your software could handle higher "multiplicity".

I was wrong, and for that I apologize my ignorance.




I wonder (to my self, probably) if Mathematica, MatLab, MathCad or Maple could handle the decryption of homophonic ciphers with multiplicity > 340?

Do any of them have a programmable cryptographic toolbox? Surely one could be built....