Just a hoax?

[JoJo_Jost]

Could you say which books please.   I have only read papers on historic encryptions and would like to know more.

Sure, but the books are in German. You can find these two free on the internet, but they're also in German – sorry...

Die Geheimschrift im Dienste der Päpstlichen Kurie von ihren Anfängen und bis zum ende des XVI. Jahhunderts
(Cryptography in the service of the Papal Curia from its beginnings to the end of the 16th century)
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(The beginnings of modern diplomatic secret writing)
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But you can find many examples of ciphers from that period (S. 171 ff first book). And I think that makes it clear that a Naibbe cipher is anachronistic. However, the Naibbe cipher is not about chronological classification, but merely about whether such a thing is even possible.