Two questions must be kept apart: is the object genuine, and can the text be read? On the first, the evidence is decisive. In 2009 the University of Arizona radiocarbon-dated four independent parchment samples, obtaining a consistent range of 1404-1438 CE; pigment and ink studies are compatible with that period. The book is therefore an authentic early-fifteenth-century manuscript, not a modern fake, though the ink itself was not dated, leaving open when the writing was added. On the second question, no proposed decipherment has won scholarly acceptance.
Professional cryptographers, including William F. Friedman, could not break it, and later claims of solution, natural languages, ciphers, constructed systems, have repeatedly failed peer scrutiny. A live minority view holds that the text may be meaningless, an early-modern hoax designed to look like a book of secrets; statistical features of the script are cited both for and against genuine linguistic content. The scholarly consensus is honest agnosticism: a real book whose message, if any, is still unknown.