A cipher used by the Prince of Conti at the time of the Fronde was broken by George Lasry, as was reported in HistoCrypt 2023. The cipher is what I would call a keyphrase cipher.
Since the keyphrase cipher is usually polyphonic, his paper is also interesting as a demonstration of solving a polyphonic cipher.
Now, I added a reference to this in "A Polyphonic Substitution Cipher of the Catholic League (1592-1593)", where I'm collecting specimens of polyphonic ciphers.
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