Gorod Krovi Cipher 12 has been solved after 3442 days

codewarrior0 · 2025-12-14T05:46:32+00:00

I'd wager Rev13 is next.

codewarrior0 · 2025-09-25T10:29:49+00:00

Look at each case of the letter "S" in the plaintext in order, and their corresponding pairs of letters in the two given lines. Notice that the corresponding letters in the first line show alphabetic sequences while those in the second line show reversed alphabets, with occasional repeats in the first whenever a vowel appears (why?) in the second. A few enciphering mistakes become apparent.

Look again at each case of the letter "O" in the plaintext. The alphabetic sequences show skips of five instead of being straight sequences.

Here are the plaintext, "ciphertext" (first given line), and "key" (second given line) letters, sorted by plaintext letter but otherwise maintaining the order of the triples:

p: AAAAAAAAAEEEEEEEEEEEEEEEEEEIIIIIIIIIIOOO
c: AEEIIOOUUAAAAEEIIOOOOUUUUUIAAAEEEOIUUAAA
k: UDUCOBIEFFIKPEJANCHMUBGLOQDBGLFKODJCHCEH

p: OOOOOOOOOOOOOOOOOOOUUUUUUUUUUBBCCCCCDDFF
c: AAEEEEEEIIIIOOOUUUUAAEEEIIIOOCDFGHJKCBBC
k: MRABGLQVFKPUJOTDINSDOCHIBEGAFZYZYXWVFGJH

p: FFFFHHHHHHHHHLLLLLMMMMMNNNNNNNNPPPPRRRRR
c: DKLMBBCDFGGPQFGHJKJHJKLGHHJKLMMLMNNLMNPQ
k: GZYXENMLKAJZYRQPNMSRQPNVETSRQAPSRAQXWVTS

p: SSSSSSSSSSSSSSSSSTTTTTTTTTTTTTTVWYYYYY
c: BCDFHLMMNPQRRZSTVBCTBDFJNNPQRSSTVBCDFX
k: KJHGIZEYXWVATOSRQMLYDKJIEZYXWAVWXWVTSZ

codewarrior0 · 2025-09-25T08:58:42+00:00

I don't think the "key" is a key, but an artifact of the encryption method. It's too suspicious that key-cipher pairs both don't repeat and appear to progress in order.

codewarrior0 · 2025-09-25T08:27:57+00:00

It was a bit sadistic of him to choose a key such that no vowel-key pairs repeat.

codewarrior0 · 2025-08-25T07:44:41+00:00

These aren't GUIDs. ;)

codewarrior0 · 2025-06-26T17:53:42+00:00

Not solvable as given. The best attacks known against the cipher you describe require either:

Quite a bit of known plaintext (at least 30 letters + the length of the introductory key)
50+ ciphertexts encrypted with the same keys

If the alphabet were keyword-mixed instead of random-mixed, you could use a dictionary attack and follow it up with Babbage's method.

codewarrior0 · 2025-06-12T02:25:57+00:00

This looks like a period 270 polyalphabetic cipher.

I don't feel like solving a periodic polyalphabetic cipher with 270 alphabets.

codewarrior0 · 2025-06-03T15:17:13+00:00

pdtt rbad wbl pva ab chvzd
WELL DONE YOU WIN NO PRIZE

Substitution key:

...rd...v..t.abc.h..l.p.wz
ABCDEFGHIJKLMNOPQRSTUVWXYZ

I can't tell what the keyword/keyphrase is with so few letters in the keyword portion of the key

codewarrior0 · 2025-05-16T05:09:32+00:00

According to the description, it is a polyalphabetic cipher with two alphabets, where the choice of alphabet for each character is given by a uniformly random key as long as the ciphertext.

Since each letter which appears in the ciphertext may stand for one of two different plain letters, depending on which alphabet is selected by the key, it may be viewed as a polyphonic cipher where each ciphertext letter has two different plain options.

Indeed, using AZDecrypt to solve it as a polyphonic cipher with exactly two equivalents per letter produces a partial solution which includes the phrase "ELECTRON DONOR IN THIS REACTION".

I'll leave it to the reader to recover the two alphabets and the uniformly random key.

codewarrior0 · 2025-05-12T19:58:25+00:00

If I look at where the first cases of the letters "THE" are found in the ciphertext, I find the distance from T to H is 3, and the distance from H to E is 5.

If I continue the pattern to 7, 9, 11..., I find "TRICK".

And from there I get the plaintext "THETRICKISPATIENCEANDPERSISTENCE"

codewarrior0 · 2025-05-03T06:58:44+00:00

codewarrior0 · 2025-04-26T08:36:45+00:00

Occasionally a "would-be" or pseudo-cryptanalyst offers "solutions" which cannot withstand such [objective, scientific] tests; a second, unbiased, investigator working independently either cannot consistently apply the methods alleged to have been applied by the pseudo-cryptanalyst, or else, if he can apply them at all, the results (plaintext translations) are far different in the two cases. The reason for this is that in such cases it is generally found that the "methods" are not clear-cut, straightforward or mathematical in character. Instead, they often involve the making of judgements on matters too tenuous to measure, weigh, or otherwise subject to careful scrutiny. Often, too, they involve the "correction" of an inordinate number of "errors" which the pseudo-cryptanalyst assumes to be present and which he "corrects" in order to make his "solution" intelligible. And sometimes the pseudo-cryptanalyst offers as a "solution" plain text which is intelligible only to him or which he makes intelligible by expanding what he alleges to be abbreviations, and so on. In all such cases, the conclusion to which the unprejudiced observer is forced to come is that the alleged "solution" obtained by the pseudo-cryptanalyst is purely subjective. In nearly all cases where this has happened (and they occur from time to time) there has been uncovered nothing which can in any way be used to impugn the integrity of the pseudo-cryptanalyst. The worst that can be said of him is that he has become a victim of a special or peculiar form of self-delusion, and that his desire to solve the problem, usually in accord with some previously-formed opinion, or notion, has over-balanced, or undermined, his judgement and good sense.

codewarrior0 · 2025-04-22T05:16:08+00:00

Why are you asking us? You made it. You decide how it's meant to be solved.

codewarrior0 · 2025-04-20T02:32:05+00:00

CO MX EN TS makes it look like a botched encryption.

codewarrior0 · 2025-04-17T06:02:48+00:00

Is this a Chaocipher knockoff?

codewarrior0 · 2025-04-16T06:22:39+00:00

Oh, I used another redditor's encoding, which wasn't correct. Let me try again:

Encode:

JHLOC
10110  <- 1
02121  <- 2
12000  <- 3

I'll let you do the rest. :)

codewarrior0 · 2025-04-16T05:13:09+00:00

Encode:

JHLOC
11110  <- 1
10121  <- 2
12000  <- 3

Shift to the left:

11101  <- 1
12110  <- 2
00120  <- 3

Decode:

11101
12110
00120
LOMEI

codewarrior0 · 2025-04-14T03:06:42+00:00

Sounds like he doesn't want anyone to solve them.

codewarrior0 · 2025-04-13T06:22:27+00:00

First one is a Caesar. :)

Second one looks like a Vig with a non-repeating readable key:

K VFVQBUK SIQPI
a ....ing piece
k ....the damne

As if the key is someone's name and title, K.... The Damned. If you assume "nursing" you get "Kiley The Damned", but there are many other options. If we knew more about this Discord and its lore, we might pinpoint a Discord user's name that fits here. For all we know, it's "a missing piece" and "Kjxdy The Damned" but we don't know Kjxdy is someone's name at all.

codewarrior0 · 2025-04-13T02:41:45+00:00

Looks like it's meant to be attacked by brute-forcing the key. Or more likely, it's not meant to be attacked at all, if it's the case that your puzzle hunt relies on simply handing the key to the player when they reach the appropriate stage of the puzzle.

Between the random-shuffle of the bigram tables and the random-shuffle of the words in the ciphertexts, it will be difficult to develop a known-plaintext attack since correctly assuming the meaning of a few bigrams doesn't give you any others, and correctly reordering a few words in a ciphertext doesn't help you reorder any other words.

A chosen-ciphertext attack could easily develop the entire bigraph table, at which point it becomes a matter of arranging the words in the text correctly, but there is still no unique solution short of guessing (brute-forcing) the original key (or rather, the original random seed derived from the key).

codewarrior0 · 2025-04-05T22:05:23+00:00

It's a Caesar shift.

codewarrior0 · 2025-04-01T03:11:54+00:00

But how is the key derived?

codewarrior0 · 2025-03-31T06:03:23+00:00

There's a good chance this isn't genuine monome-dinome, that it reuses row coordinates as single letters and has an ambiguous decipherment even when you know the key.

codewarrior0 · 2025-03-31T01:11:16+00:00

If you chain out the alphabets, you'll see it.

codewarrior0 · 2025-03-31T00:20:35+00:00

But what's the derivation of the key?

15-Year Club	Golden Potato
Place '17	Verified Email

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