The Voynich manuscript — often called the most mysterious manuscript in the world — has eluded attempts to understand its origin, nature, and purpose for centuries. Its text is made up of a strange collection of glyphs, strung together in bizarre-looking, unreadable words that surround otherworldly illustrations. In a new study, independent researcher and science journalist Michael Greshko investigated the hypothesis that the manuscript is compatible with being a ciphertext by attempting to develop a historically plausible cipher that can replicate the manuscript’s unusual properties.
The Voynich manuscript, folio 67r. Image credit: Beinecke Library, Yale University.
The Voynich manuscript, named after the antiquarian Wilfrid Voynich, is a small book 23.5 x 16.2 cm of about 240 pages.
Nearly every page of the book contains scientific and botanical drawings in various shades of green, brown, yellow, blue, and red.
“The Voynich manuscript’s parchment was made in the early fifteenth century (1404-1438), and in its construction and illustrated content, the manuscript resembles books made during the early 1400s in central Europe, especially those from the region around the Alps,” Greshko said.
“Three main schools of thought have emerged on the nature of the manuscript:
(i) that it is meaningless gibberish perhaps created as glossolalia or as a means of running a Medieval scam;
(ii) that it represents an early artificial language, or perhaps the written form of an obscure or previously unknown natural language;
(iii) that it represents a ciphertext of a well-known natural language such as Latin, Italian, or German.”
In his new work, Greshko described a cipher that reliably encrypts Latin and Italian texts as decipherable ciphertexts that replicate many properties of the Voynich manuscript at once.
“Named after a 14th-century Italian word for a card game, the Naibbe cipher is a verbose homophonic substitution cipher that maps individual letters in a Latin or Italian plaintext onto multiple distinct strings of Voynichese glyphs,” he explained.
“The cipher is designed to be executable with materials available in or around the Alpine region during the early fifteenth century.”
“It works by mapping letters onto multiple distinct strings of Voynichese glyphs, producing words that follow an expanded version of the slot grammar observed in the manuscript itself.”
The results suggest that the ciphertext hypothesis for the Voynich manuscript remains viable.
“Playing cards are also historically plausible, having been introduced to Europe in the late fourteenth century via trade with the Mamluk Sultanate,” the researcher said.
“Decks of 52 and 78 playing cards are known from 15th-century Europe, and confirmed records of playing cards within Italy date back to 1377, in the form of a Florentine prohibition on the foreign card game naibbe, a term likely derived from Arabic.”
“Playing cards are also known from around the Alpine region specifically: Venice built up such a robust card-making industry during the early fifteenth century that by 1441, Venetian artisans were already lamenting the industry’s decline.”
“I have designed two variants of the Naibbe cipher,” he added.
“One uses the 78-card tarocchi (tarot) deck, which was created in 15th-century Italy to play trick-taking card games.”
“The other variant uses a standard 52-card deck, whose basic design was established in the Mamluk Sultanate.”
The Naibbe cipher’s very existence suggests that the Voynich manuscript may be compatible with being a Latin or Romance-language ciphertext.
“As far as I am aware, the Naibbe cipher is the first substitution cipher ever described that has offered systematic explanations for how a substitution cipher could have modified the properties of Latin, Italian, [or] German into those of the Voynich manuscript,” Greshko said.
“However, the Naibbe cipher’s incomplete replication of Voynich B’s properties underscores the difficulty of achieving a comprehensive cipher-based model for Voynich manuscript text generation.”
“I hope that the Naibbe cipher inspires new computational analyses of both Voynich manuscript-mimic ciphers and the Voynich manuscript itself — and that someday soon, the low hum of the Voynich manuscript’s six-century mystery and the cacophony of a century’s worth of analysis will give way to melodious harmony.”
The study was published in November 2025 in the journal Cryptologia.
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Michael A. Greshko. The Naibbe cipher: a substitution cipher that encrypts Latin and Italian as Voynich Manuscript-like ciphertext. Cryptologia, published online November 26, 2025; doi: 10.1080/01611194.2025.2566408
