Dee didn't translate the Necronomicon. That little gem came from a story of science fiction writer Lin Carter. And Carter made it up.
Here's a page you might find of
And as for proof, let me be lazy and cut and paste the second page on that site.
To help would-be Necronomicon discoverers, here are some common claims and the necessary evidence to back them up:
Lovecraft knew that the Necronomicon was real: Direct quotes from Lovecraft's letters indicating that he knew this (include name of recipient, date,
and publication and/or location of letter). Otherwise, verified biographical material taken from reminisces of friends, city records, etc.
The Necronomicon pre-existed Lovecraft: A pre-1920 copy of the Necronomicon (see below). Otherwise, documents from pre-Lovecraft times which mention
the Necronomicon (list author, title, date, page reference, quote, and location of the particular copy). NOTE: The Egyptian and Tibetan Books of the
Dead bear little resemblance to the Necronomicon mentioned in Lovecraft's work; if you want to prove that they were the originals, you should come up
with biographical evidence to prove that Lovecraft did indeed read them before 1920 (see above).
Copy of the pre-Lovecraft Necronomicon: The best way to prove this would be to make copies or photographs of the title, copyright, and several other
pages of the book. If the book is held in a library collection, include a print-out of the card catalog entry and the address and phone number of the
person in charge of the collection which holds it. If the book is in a private collection, the owner's name, address, and phone number will be
required. (This is only to get us started; evaluating such a copy will obviously require testing and expert opinions.) In addition, double-checking to
make sure the copy was published before 1920 will save us both a lot of work.
A secret society covered up the book's existence/had Lovecraft as a member: This assertion requires a) proof that such a society does exist (with
relevant citations), and b) that Lovecraft was connected in some way with one of its members (once again, with citations linking one to the other).
The following do not constitute evidence, so don't bother sending assertions based solely on them:
Speculation on what kind of person Lovecraft "really" was.
The power of Lovecraft's fiction ("it's so good, it must be real!").
Claims that you or someone you know has the Necronomicon but can't possibly show it to anyone or let anyone contact you (this means you from
Claims that the Necronomicon's existence has been covered up by the government or a cult, without evidence of such a program in place. (Evidence must
be something besides the fact that no one can find the Necronomicon).
What you heard someone on the Internet say (I'm starting to think we should dub this technological wonder the "Misinformation Superhighway").
What your buddy at school/work/the club/whatever told you.
The hoax Necronomicons. (If someone was able to find a pre-1920 manuscript of one of these, that might be acceptable, but nothing published after then