[SOLVED] Gorod Krovi Main Cipher Thread

[irebased]

[SOLVED] Gorod Krovi Cipher

Ciphertext Copy/Paste

Rc qipv jhx vld plson fhceuh itp jui gh qhzu dg sq xie dhw. U gbfl lf fluz pcag wrgkv zw, dinyg zw, qge gnvm L fhx.

Overview

The Gorod Krovi cipher (GK Cipher for short) is detected by Boxentriq as an autokey Vigenere cipher, though this has not been proven, and attempts to brute force a Vigenere cipher have come up short.

• The cipher is found on the map Gorod Krovi
• The cipher is in sentence structure, including punctuation and mixed casing.

Progress as of this post

There are several running theories:

• The shopping list cipher is somehow used to solve this cipher, maybe as a key
• The Kronorium excerpt numbers are potentially used, but one of them "Excerpt B" is broken as it was incorrectly translated from the encrypted Navajo code form, which doesn't support numbers
• The cipher might use some of the wheels from wheel cipher machines found in the map
• There is an interesting but non-uniform period found depending on the patterns you look at. The repeating zw vs repeating hx are on different periods depending on if you consider punctuation and spacing as characters which consume the key when iterated over or not. Some sites like Cryptii V2 did consume key characters for spaces and punctuation, but did not change their value and instead left them as-is. Given all tools have these quirks that got ironed out over time, we will need to use old versions of tools using archives or, if open source, forking the repo and reverting back to a commit from around Q1 2016.

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Update 12/13/2025: Solved!

This cipher was solved by JessesOcean and WXAudio. It is a Vigenere Autokey cipher with a custom alphabet, and can be reproduced here.

Alphabet key: ZOMBIESAREEVERYWHERE
Key: TRYTHIS

Plaintext:

We have won the great battle and now we must be on our way. I fear he will come after us, after me, for what I did.