Design a Lighthouse Cipher
Create a nautical puzzle by combining Polybius coordinates with a second transformation, and give another learner enough clues to reverse it.
Start with the Polybius exhibit →Breaking Confederate Vigenère
Study the historical brass-disk convention, then compare its repeated-key weaknesses with ordinary Vigenère analysis.
Open the Confederate Vigenère exhibit →Room 40 and the Zimmermann Telegram
Trace how accumulated codebook recovery and an older-code retransmission helped Room 40 read and safely disclose the telegram.
Open the Zimmermann exhibit →Create an Enigma Challenge
Choose rotor, ring, plugboard, and starting settings in the exhibit, encrypt a short dispatch, and challenge a classmate with a crib.
Open the Enigma exhibit →Hill Cipher: When Linear Algebra Attacks
Use matrix inversion modulo 26 to see how enough suitably independent known-plaintext blocks can recover a Hill key and why linearity is the cipher's central weakness.
Open the Hill cipher exhibit →The Uncracked Dorabella Cipher
Edward Elgar's 1897 cipher letter to Dora Penny remains unsolved after more than 125 years — an 87-character mystery in 24 unique symbols.
Open the Dorabella exhibit →Draft a Fact or Write-up
Have a sourced historical fact, a challenge solution, or a cipher puzzle to share? This static-site tool downloads a text draft to your device. It does not transmit or submit anything. When ready, attach or paste the draft into a GitHub issue for review.