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+--- Thread: Historical ciphers, when they were introduced and their effect (/thread-4712.html)
Historical ciphers, when they were introduced and their effect - Koen G - 20-05-2025
After having read the paper by Marco Vito that was highlighted by Mark here: You are not allowed to view links. Register or Login to view. , I feel like we need a to the point overview of which ciphers were used in the 15th century, when they were introduced and what their effects would be. Could they make a plaintext more like Voynichese, or do they have an opposite effect?
Your input, additions and corrections will be very much required and appreciated. If this turns into something decent, I can make an easy to find version of it in the curated subforum. This might be helpful for newcomers.
1) Simple substitution.
- Each letter of the plaintext consistently corresponds to a symbol of the ciphertext. (Example: Caesar cipher).
- Existed before the 15th century.
- Popular with solvers, but there is a broad consensus among scholars that the Voynich text is not the result of a simple substitution cipher.
2) Introduce nulls.
- Some extra characters in the ciphertext don't correspond to anything. This can be used to obscure the most frequent characters, break up common bigrams etc.
- Existed before the 15th century (?)
- Effects: larger glyph set, increased entropy (sometimes or always?)
3) Homophonic cipher
- Each plaintext letter can be replaced by multiple ciphertext symbols. Hides frequency -> harder to crack
- Existed before the 15th century (?)
- Effects: larger glyph set; I would expect higher entropy but I'm not sure.
4) Polyalphabetic, "Alberti" cipher
- Allows the encoder to shift to a different substitution alphabet within the same cipher.
- Leon Battista Alberti, 1466 (-> significantly later than Voynich MS). Existed earlier e.g. in Arab sources.
- Effects: glyph set may remain the same; any textual patterns are obscured.
5) Steganography
- Any method where the actual information is hidden within less suspicious data. Hard to rule out: the only limit is your imagination. Note: the Voynich manuscript appears encoded or "secret" throughout, so it would be an edge case of steganography to begin with if any actual info is concealed in what already looks like a ciphertext.
RE: Historical ciphers, when they were introduced and their effect - Koen G - 20-05-2025
RE: Historical ciphers, when they were introduced and their effect - Koen G - 20-05-2025
RE: Historical ciphers, when they were introduced and their effect - tikonen - 20-05-2025
RE: Historical ciphers, when they were introduced and their effect - R. Sale - 20-05-2025
RE: Historical ciphers, when they were introduced and their effect - Mark Knowles - 20-05-2025
RE: Historical ciphers, when they were introduced and their effect - Mark Knowles - 20-05-2025
RE: Historical ciphers, when they were introduced and their effect - Mark Knowles - 20-05-2025
RE: Historical ciphers, when they were introduced and their effect - Koen G - 20-05-2025
RE: Historical ciphers, when they were introduced and their effect - Rafal - 20-05-2025