Oral Cipher in Yoshiwara Pleasure Quarters in Edo

Women in the Yoshiwara pleasure quarters in Edo in the late eighteenth century used a cipher, called the Fukagawa Speak, in their conversation. I learned this from a contemporary novel depicted in a scene in a historical drama I watched on TV the other day. The scheme is simple enough: meaningless syllables "ka", "ke", "ki", "ko", "ku" are inserted in the message. But when used in conversation, the resulting sound would have been unintelligible to untrained ears.
Similar schemes, typically known as the tanuki cipher, have also been used in riddles for kids. (Tanuki means a raccoon dog, but may also be interpreted as "drop ta".)

And, of course, it's not limited to Japan. Even John Wilkins' Mercury (1641) mentions an example of a similar scheme: Ougour plogot igis digiscogovegereged.
A Japanese translation of a mystery novel in English uses the Fukagawa Speak to render secret conversation in "King Tut English" among kids: A-bub-shush-o-lul-u-tut-e-lul-ylum.

I described these in a new article in Japanese, 深川言葉　―　大河ドラマ「べらぼう」に出てきた遊里の暗号.

Substitution Cipher for Hangul Text in a Book for Kids

The other day, I said I was looking for a cipher in Hangul. Now, I've found the book I have been looking for. It is a Korean translation of a book in Japanese, which features a cipher. Although the ciphertext is not in Hangul but in graphic symbols, this is the first ciphertext for Korean I encountered. I uploaded a new article, "Substitution Cipher for Hangul", which supersedes my post the other day.
(There is also a Chinese version of the book. It would be interesting to see how the cipher was adapted into Chinese. The Taiwan version skips the relevant volume (vol.11), so we need to look for Hong Kong or Mainland Chinese version.)

D'Estrades' Ciphers with Mazarin and Others

I added ciphers used in the correspondence of Comte D'Estrades in "Ciphers Early in the Reign of Louis XIV". Most of the keys are now identified, but a key for a letter in Italian (BnF Clair. 577, p.629) is not. The interlinear decipherment of the first few words (wihch I partly parse as `41(L) ¨33(AR) ¨36(MA) ′56(TA) ¨56(NA) ′61(VA) `42(LO)) may allow one to reconstruct the whole code.

(15 Mary 2025: I uploaded the key for the remaining Italian cipher reconstructed by George Lasry and Norbert Biermann. My parsing should be corrected in various ways: `41(LA) ¨33(R) ¨36(MA) ′56(TA) ¨41(NA) ′61(VA) `42(LE).)