Atbash (Reverse Alphabet) Cipher

Atbash is the cipher with a history and zero keys. It maps each letter to its mirror in the alphabet - A becomes Z, B becomes Y, C becomes X - and that's the entire algorithm. It dates back to the Hebrew Bible (the name comes from the first, last, second, and second-to-last letters of the Hebrew alphabet), and in the modern puzzle world it shows up constantly as the "cute first step" in an ARG: it's solvable by eye once you know the trick, which makes it the perfect warm-up clue before a real cipher shows up.

Because it's a straight substitution, Atbash is its own inverse - encrypting twice gets you back to the original text, and encrypting is the same operation as decrypting. The ARG Toolkit node still gives you a mode toggle because every classical cipher in the pack shares a common interface, but flipping it changes nothing about the math. That shared interface also means Atbash sits in the same "Cryptography → Classical" menu as the rest of the pack's ciphers, with the same text, alphabet, keep_formatting, and mode inputs and the same single encrypted_txt STRING output. The only difference from its siblings: no key input, because there's nothing to key.

The inputs

• text - your message. The only input you'll actually touch.
• alphabet - defaults to ENGLISH. This is the one knob Atbash genuinely has: change the alphabet and the mirror changes with it. It accepts the named alphabets secretpy defines, so you can run a non-English Atbash by typing, say, the Russian alphabet's name here.
• mode - encrypt/decrypt. Mathematical no-op here, but harmless.
• keep_formatting - preserve spaces/punctuation (and case) or strip to a clean lowercase string.

Where people get burned

The number one Atbash "failure" is expecting a key. People wire this up, realize there's no key port, and assume they grabbed the wrong node - they didn't. The real operational gotchas are subtler: if keep_formatting is off, the output is a stripped lowercase string that won't preserve your original layout, which matters when you're crafting a clue that's meant to look like a sentence. And if you're checking your result against an online Atbash tool, remember the alphabet question - an English result and a Hebrew-ordered result for a 26-letter alphabet are the same, but custom alphabets diverge fast.

One more thing worth knowing: because Atbash is a monoalphabetic substitution, it's trivially breakable with frequency analysis. Don't use it for anything you actually need to hide. Use it as the pack does - the "this is definitely a puzzle, now solve it" layer.

Installing it

Part of the ARG Toolkit pack, standard install:

cd ComfyUI/custom_nodes
git clone https://github.com/AzelusLightvale/ComfyUI-ARG-Toolkit

Restart ComfyUI and it's under ARG Toolkit → Cryptography → Classical (ComfyUI Manager: search "ComfyUI ARG Toolkit"). Depends on secretpy for the classical ciphers; Manager installs it, manual clones need pip install -r requirements.txt. Pure Python, nothing heavy.

Troubleshooting

• "There's no key input" → correct, that's the cipher. It's an involution; encrypt and decrypt are the same operation.
• Output has no spaces/case → toggle keep_formatting back on.
• Comparing to an online tool and they differ → check alphabet selection and formatting; the core mirror is universal.

Atbash is the cipher you hand to someone who's never met a cipher before, and that's a feature, not a limitation. In a multi-step ARG it earns its place as the friendly on-ramp clue between "you found a code" and "the code means something."