Supplementary files for "The Naibbe cipher: a substitution cipher that encrypts Latin and Italian as Voynich Manuscript–like ciphertext"

This repository contains code and datasets associated with the paper: Greshko, Michael A. (2025). The Naibbe cipher: a substitution cipher that encrypts Latin and Italian as Voynich Manuscript–like ciphertext. Cryptologia. https://doi.org/10.1080/01611194.2025.2566408 In the work represented here and in the associated study, I investigate the hypothesis that the Voynich Manuscript (MS 408, Yale University Beinecke Library) is compatible with being a ciphertext by attempting to develop a historically plausible cipher that can replicate the manuscript’s unusual properties. The resulting cipher—a verbose homophonic substitution cipher I call the Naibbe cipher—can be done entirely by hand with 15th-century materials, and when it encrypts a wide range of Latin and Italian plaintexts, the resulting ciphertexts remain fully decipherable and also reliably reproduce many key statistical properties of the Voynich Manuscript at once. My results suggest that the so-called “ciphertext hypothesis” for the Voynich Manuscript remains viable, while also placing constraints on plausible substitution cipher structures.