Community puzzle
Cipher Challenge
A two-system puzzle built with the same hand-executable methods available to Sanborn and Scheidt in 1989.
The Ciphertext
97 characters. Two classical systems. Pencil and paper only.
Rules
- Both systems are classical. No electronic computation was used in the encryption. Everything can be done with pencil, paper, and a tableau.
- The methods are from the historical toolkit: the same families available to a cryptographer in 1989.
- The plaintext is English. Uppercase letters only, no spaces or punctuation. Deliberately somewhat enigmatic in style.
- A complete solution identifies: the full plaintext, the nature of both systems, and the key material for each.
Hints
“The message uses two systems, as confirmed.”
“One system hides. The other transforms.”
Two words in the plaintext serve as confirmation cribs. One is 8 letters and relates to direction. The other is 8 letters and relates to vision.
Verify your answer
Enter your proposed plaintext to check it instantly. Correct answers trigger a notification to the puzzle creators.
Offline verification
SHA-256 of plaintext:
ab491ee62d455cf627859b836591c355643b7da738ce4f6a55aacf6743fdae51
Verify locally: echo -n "YOURANSWER" | sha256sum
Why this puzzle exists
After testing over 671 billion configurations and 105,000+ multi-layer compositions, we wanted to test something different: can a puzzle built with the same classical toolkit resist our automated framework while remaining solvable by skilled human cryptanalysts?
If you solve this using a technique we haven’t tried on the real problem, we want to know about it.