'Deniers have repeatedly attacked the authenticity of the famous
Diary of Anne Frank, which tells of the young Jewish author's experiences as she and her family hid from Nazi persecution in Holland. It seems they believe that by creating doubts about this popular book, which is often a young person's first encounter with the literature of the Holocaust, they can generate broader doubts about the Holocaust itself. Their attacks on the diary became so widespread, that eventually the Netherlands State Institute for War Documentation, the archives to which Anne's father left the work, subjected the glue, paper and ink of the diary to extensive forensic tests. They found them all to be from the 1940s.'
'The investigators compared Anne's handwriting in the diary to other samples of her writing, including letters she wrote before going into hiding, and traditional student autograph books she signed before the war. The tests found the handwriting to be that of the same person. In fact, every test to which the diary was subjected proved that this was a genuine World War Two era work by a teenager.'
BBC - History - World Wars: Denying the Holocaust