Did R. Shimon Bar Yohai Write the Zohar?

Dear Kavod HaRav, Shalom U’Brachot.
What do you think about the Zohar’s authenticity? Do you recognize it as the Holy Zohar/ Zohar HaKadosh or do you reject the claim that it comes from the Tanna Rabbi Shimon bar Yochai?

The Zohar literature, which includes the Zohar, Zohar Hadash, Midrash HaNe’elam, Tiqune Zohar and several other works, was written, almost certainly by different authors, in 13th century Spain. None of it was written during Mishnaic or even Talmudic times. Much has been written on the subject, including the seminal work of the Ya’abess (R. Ya’aqov Emden) z’l, Mittpahath S’pharim (http://hebrewbooks.org/33319), written some 250 years ago, in which he adduces copious and convincing proof that the Zohar was written in Spain during the period of the Rishonim. Certain parties have endeavoured, with no small success, to make this book unavailable; this should tell you something about the book’s power. For those familiar with the works of the Ya’abess this will come as no surprise. A new edition was printed by HaRav Ben-Ssiyon Kohen z’l of Jerusalem about 15 years ago.
I will mention just one example of such proof. According to the Zohar (Sh’moth 48b) the T’kheleth dye was produced from the Hilazon (sea snail) that is found in the Kinereth. In the first place this contradicts Hazal who state (TB Shabath 26a) that the Hilazon is to be found along the Mediterranean coast. Secondly, it contradicts what was common knowledge in the ancient Mediterranean basin regarding the source of this and similar dyes, as described in Greek (Aristotle) and Roman (Pliny the Elder, Natural History, 9: 60-65) sources. Thirdly, no such creature does or can exist in the Kinereth or any body of fresh water, a fact mentioned by Pliny. Fourthly, only a Jewish mystic living and dreaming in 13th century Spain could have been so ignorant of what was common knowledge in Eress Yisrael in the days of Hazal.
For those whose perception and understanding of Tora is based upon misinformation, this truth is a bitter pill to swallow. To a person who has invested years, perhaps a lifetime, pursuing a phantom, this will come as a great shock. This is only to be expected. If you discuss this matter with such people and sense their inability to deal with the matter rationally, you might consider changing the subject.
The teachings of the Zohar range from profound to inane, from insightful and enlightening to misleading and even heretical. It should only be studied by those of superior intellect who have dedicated themselves for many years to the in-depth study of Tora based on the primary sources. The capacity for critical thought and caution are essential. The masses are to be discouraged from studying it.
Rabbi David Bar-Hayim