Cryptology

Puzzles

• FeynmanWhat are the Feynman ciphers?
• VoynichWhat are the Voynich ciphers? Added material
• blum.primesWhat are some moderately large primes that leave remainder 3 when divided by 4 ("Blum" primes), for... New
• calloway.codeDecode this message: New
• coded.message.1818Can you decipher a coded message written on the cover page of a letter dated 20 February 1818? New
• codex.seraphinianusIs the invented script of Luigi Serafini's "Codex Seraphinianus" a real (or enciphered) language, and how... New
• dorabellaWhat is the Dorabella cipher? New
• kryptosWhat is the Kryptos cipher?
• marlow.challengeMarlow's job last week took him on an exciting trip. New
• opendoor.indexWhat did the National Security Agency's OPENDOOR index of declassified cryptologic documents list? New
• phantom.tollboothDecipher the numeric message from the Mathemagician to his brother in Norton Juster's "The Phantom Tollbooth": New, unsolved
• swiss.colonyWhat are the 1987 Swiss Colony ciphers?
• vcrplusWhat is the code used by VCR+?