Hall XII · Open Problems · Living Research

Unsolved Ciphers

Ten cases involving unresolved inscriptions, incomplete decipherments or uncertain interpretation. Their evidence and solution status differ; consult each exhibit’s dated sources.

"Every solved cipher started as an unsolved one. The Phaistos Disc has been waiting since 1908. Kryptos K4 has been waiting since 1990. The Voynich Manuscript has been waiting since 1404 (carbon-dated)."

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Unsolved is not the same as unbreakable. Some cases may be ciphers, others unknown writing, private notation or hoaxes. Archival plaintext discovery, a proposed interpretation and a reproducible cryptanalytic solution are distinct outcomes.

XII · 1 Voynich Manuscript The Voynich manuscript remains undeciphered. Radiocarbon dating concerns its parchment; script, language and interpretation remain unresolved. ~1404 CE XII · 2 Kryptos (K4) Kryptos: K1–K3 publicly solved; K4 plaintext recovered from an archive in 2025, without a publicly demonstrated cryptanalytic solution. 1990 XII · 3 Beale Ciphers (1 & 3) Beale ciphers — three numerical ciphers published in an 1885 Lynchburg pamphlet, said to have been written in the 1820s and to point to a Virginia treasure. Only #2 was solved (Declaration of Independence key); #1 and #3 unsolved. 1822-1885 XII · 4 Dorabella Cipher Edward Elgar’s 1897 Dorabella cryptogram contains 87 symbols. No proposed reading has achieved general acceptance. 1897 XII · 5 Zodiac Z-13 & Z-32 Zodiac killer ciphers (1969) — homophonic substitution as in Z-408 (broken in 1969 by the Hardens) and Z-340 (broken in 2020 by Oranchak, Blake, and Van Eycke). 1969-1970 XII · 6 Shugborough Inscription An 18th-century English garden monument bearing the cryptic letters O · U · O · S · V · A · V · V — debated for 250 years and never definitively cracked. ~1748 XII · 7 D'Agapeyeff Challenge A 1939 textbook 'cryptogram for the student' that the author himself later admitted he had forgotten how to solve. 1939 XII · 8 Somerton Man (Tamám Shud) The Somerton Man inscription: uncertain letter groups associated with a 1948 death. Researchers proposed Carl Webb’s identity in 2022; the inscription’s meaning remains unconfirmed. 1948 XII · 9 McCormick Notes Ricky McCormick’s two handwritten notes, released by the FBI in 2011 for public help. Their meaning and writing system remain unresolved. ~1999 XII · 10 Phaistos Disc The Phaistos Disc is a Bronze Age stamped inscription from Crete. Its language and reading remain disputed; it is not established as a cipher. ~1700 BCE

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How an "unsolved" exhibit can become a "solved" one. The path runs through one or more of: (a) statistical attack — the Oranchak–Blake–Van Eycke solution of Z-340 in 2020; (b) computational search — the Beáta Megyesi team's 2011 reconstruction of the Copiale cipher key; (c) archival discovery — a key, plaintext, or contemporary commentary surfaces; (d) cross-disciplinary linguistics — Champollion's 1822 Egyptian decipherment is the model. Every exhibit on this page is open to all four routes.

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