Voynich is encrypted ENOCH

[DG97EEB]

Why is this necessary? (I mean the encryption algorithm)

I think this is exactly the right point. Almost no one in 15th century Europe could read Ge'ez. There is zero point in encrypting it further. Admittedly it's what we now call Security by Obscurity, but given that Enoch was retained as canon by the Ethiopian church, I'd have thought like every other book of the bible that they'd want it translated in to Latin or German or Italian so more people could read it, not fewer..